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9L0-403 Mac OS X champion Essentials 10.6

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9L0-403 exam Dumps Source : Mac OS X champion Essentials 10.6

Test Code : 9L0-403
Test name : Mac OS X champion Essentials 10.6
Vendor name : Apple
exam questions : 71 existent Questions

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Apple Mac OS X Support

Are there are any VPN valued clientele for Mac OS X that usher L2TP? | existent Questions and Pass4sure dumps

Our VPN is in line with investigate factor, the usage of L2TP. Most individuals here expend home windows, but i expend Mac OS X 10.2.eight (Jaguar). Are there are any VPN shoppers for Mac OS X that attend L2TP?

according to your query, I trust you're hunting for a VPN customer that runs L2TP over IPsec, the far flung entry solution promoted with the aid of Microsoft, starting with home windows 2000. Many VPN gateway providers (including investigate element) at the dawn implemented "vanilla" IPsec (tunnel mode) for host-to-community VPNs, but maintain since introduced L2TP over IPsec (transport mode) for interoperation with the embedded home windows VPN client. it's powerful for home windows users but, as you've got found, will also subsist a challenge for others.

examine component sells a version of their VPN-1 client for Mac OS eight.x/9.x, the expend of vanilla IPsec. Apple's Mac OS X 10.three (Panther) now comprises an embedded VPN customer that supports L2TP over IPsec. you might subsist caught in between with Mac OS 10.2.8 (Jaguar). Jaguar included embedded VPN code but no longer a graphical consumer interface to IPsec. Panther expands the Mac's embedded VPN customer, adding a graphical user interface to L2TP/IPsec, and is in reality your superior alternative.

in case you can't better to Panther, you may also want to try a 3rd-party L2TP VPN customer for Jaguar. investigate point-suitable VPN consumers for Mac OS 10.2 listed at Apple's internet web page include Lobotomo IPsecuritas and Equinux VPN Tracker, despite the fact I cannot explicate from a brief study product documentation whether these consumers champion L2TP/IPsec or simply IPsec. you can also try your hand at configuring Jaguar's embedded IPsec code the expend of the command line interface. To study extra about configuring Jaguar's IPsec, see this PPT presentation with the aid of Paul Hoffman of the VPN Consortium. support in reason that you'd silent should configure L2TP on suitable of IPsec to pair with your VPN gateway's coverage.

Are Hackintosh users extra Passionate in regards to the Mac Than Apple? | existent Questions and Pass4sure dumps

A version of this publish initially appeared on Tedium, a twice-weekly e-newsletter that hunts for the conclusion of the lengthy tail.

we maintain powerful opinions about their corporate giants, what they should silent (or shouldn’t) do, or how they should (or shouldn’t) act.

We requisite them to hearken to us, and purchase into account their wants as clients and consumers. however too commonly, they Get too astronomical and that they maintain to steadiness out your interests with their personal—in addition to everyone else’s.

This, from time to time, creates situations during which a few of an organization’s largest enthusiasts feel compelled to purchase its concepts in a unique route. It’s with this in intellect that I’d want to talk about why the Hackintosh, a laptop (continually with an Intel CPU) that runs MacOS on hardware Apple does not make, is an enchanting cultural fashion, as opposed to simply a manner to sever Apple out of a share of its gains.

The roots of the fateful decision that gave us the Hackintosh date to 2001, when an Apple employee, working remote, spent his time constructing a version of Mac OS X, the then-new operating system Apple tailored from NeXTStep, that turned into confiscate with Intel’s x86 platform.

This proved a key flow, creating a backup blueprint in case PowerPC received long within the enamel (as it ultimately did), and when Apple leadership institute about this remote employee’s solo recreation, the company automatically did something surprising: It tried to persuade another company to fabricate Mac clones.

At a Hawaii golf direction, Steve Jobs met with Sony executives to display them what may technically subsist called the primary “Hackintosh,” a Sony VAIO laptop that turned into running OS X on an Intel processor.

Jobs, a fan of Sony’s, had famously been antagonistic to Macintosh clones, shutting down a clone application that had harmed Apple’s bottom line, however changed into apparently inclined to fabricate an exception for Sony, whose VAIO line was smartly-regarded on the time. but unhealthy timing on Sony’s portion killed the deal. The issue? The VAIO line turned into already a hit with home windows, so it didn’t want OS X.

The influence changed into that the realm didn’t Get an Intel Mac unless 2006. however despite Apple’s optimum early efforts, there turned into most effective so a pleasurable deal it might execute to abide away from other PCs from being able to Run its iconic operating gadget.

this may later reveal essential for one of the vital working gadget’s largest lovers.

“Your karma verify for these days: There once became a person that whined his current OS turned into so blind, he’d execute enhanced to pirate an OS that ran superb but institute his hardware declined. gladden don’t purloin Mac OS! truly, that’s approach uncool. (C) Apple computing device Inc.”

— A passage from a kernel extension, relationship to 2006, called “Don’t purloin Mac OS X.kext”. This file, a covered binary that Apple designed, virtually, to duty a affirmation that the laptop was operating actual hardware, has proven to subsist fairly feeble insurance blueprint over time, with system hackers getting past its restriction long in the past. (be positive to no longer remove it from your computing device, incidentally, besides the fact that you’re operating a suitable Mac. It’s the impeccable option to cease your Mac from working in a sole fell swoop.) despite this, Apple has made tiny trouble to toughen the feeble safety in the decade-plus considering then, with some speculating that it’s partly as a result of the proven fact that these clients are very commonly Apple valued clientele who're deeply embedded within the ecosystem—i.e. the very people a corporation love Apple wouldn’t requisite to piss off.


comic and entrepreneur Paul Chato, who has been the usage of Macs for a long time. photograph: YouTube

amongst Hackintosh’s extra high-profile users: A comic with a long historical past in tech

The Hackintosh neighborhood is, admittedly, fairly small—in no tiny half because of the technical learning curve that frequently comes with the follow. It’s effortlessly a subculture borne from the mixture of two other subcultures: Apple superfans and hobbyists who build their personal computer systems.

but it does draw in some extremely passionate clients, many of whom are experts at artistic events, partly because of the consumer groundwork Apple’s machines lengthy fostered. Case in point: Paul Chato.

nowadays, Chato is an entrepreneur who runs an internet design firm, but again in the late ’70s and ’80s, he turned into optimal referred to as a prime member of a well-liked Canadian comedy troupe named The Frantics, which had a weekly chain on CBC Radio that introduced sketches just love the legendary “last Will (Boot to the top).”

At its top, the troupe even had its personal television display, 4 on the floor, which particularly brought a very Canadian superhero, Mr. Canoehead.

notwithstanding his early success became in sketch comedy, Chato’s profession has generally been in technology, including, at one point, as the producer of a well-liked Myst-vogue event game. extra recently, notwithstanding, Chato has discovered a level of success as a YouTuber, working a vlog that offers up his irreverent tackle the commonly tech-connected issues he’s enthusiastic about.

In an e-mail interview, Chato explained that the mixture of tech and humor came naturally, appearing in Frantics sketches corresponding to “I sell computers.”

“The Frantics maintain been doubtless the first to cope with humour in comedian books and nerd lifestyles long before The massive Bang concept popularized it,” Chato noted. “So, it’s a portion of my continuum.”

The Hackintosh-pushed coverage, nevertheless, was some thing of a cheerful accident, a byproduct of his tech-linked pet peeves, lots of which can subsist regarding the proven fact that Apple doesn’t fabricate a computer for him.

Two years in the past, in a sole of his earliest clips on the channel, Chato drew attention to the proven fact that he has used Apple products for more than 30 years—from the fashioned all-in-one to numerous contemporary-day MacBook pros—however moved to producing Hackintosh machines as an alternative. “I feel absolutely abandoned by artery of Apple in terms of meeting my needs,” he cited in the video.

on the grounds that then, he’s recorded loads of Hackintosh-linked content material (along with theories as to what the long-promised Mac professional reboot may silent appear like), with one positive spotlight coming a number of months in the past, when Chato used his soapbox to discuss the style that Hackintosh brings him joy—in portion because of entire of the issue-fixing and tweaking concerned.

He stated the manner of structure a Hackintosh helped Get him nearer to his son. “Apple sort of ignores the bonding features of constructing a DIY Mac,” he advised me.

DIY and Apple don’t principally Go hand-in-hand, however even so, didn’t the trade simply inform us to “share your gifts”?

Some americans who share their gifts can’t execute it exceptionally neatly with Apple’s latest lineup.

5 alternative ways that individuals can Run MacOS without possessing a Mac
  • Patching the operating gadget. within the early days of Hackintoshing, it turned into regular for individuals in the group to fabricate expend of a literal “hacked” version of Mac OS X that they downloaded from a website, however in contemporary years, it’s eddy into extra regular to regulate the bootloader (also known as the EFI partition) to fabricate it confiscate with MacOS. the most everyday tool, Clover, has eliminated lots of the guesswork around installing—although really now not entire of it. however even if you Get it in addition, the job commonly isn’t executed, as machines maintain to basically subsist modified to deploy kernel extensions that without difficulty duty drivers or patches to aid distinct items of hardware, such as video, sound, and even USB-C ports. by artery of editing the innards of the system code, Hackintosh clients can antiseptic out the details and fabricate a computing device assist lots of the creature comforts of a Mac. That referred to, not everything can also subsist conveniently fastened—a working SD card slot in a desktop is unusual, for instance, and a microphone could now not work through your headphone jack. likely probably the most tricky aspect for many pc users is the Wi-Fi, as Apple tends to expend chips from Broadcom in its machines, rather than Intel, as most computing device manufacturers do. This commonly requires a hardware swap or the expend of a third birthday party machine, in particular on laptops.
  • The “Vanilla” method. This classification of Hackintosh flips the mannequin of the hefty kernel tweaking of the greater traditional Hackintosh approach, leaving the working system itself solitary whereas placing the quintessential modifications into the boot system. The edge of this approach is that it just about allows for the operating device to work in its purest kind devoid of including a lot of extra kernel extensions, or kext info, in the working system itself.
  • Renting somebody else’s, almost. For years, the cloud enterprise MacStadium has discovered itself within the atypical condition of constructing an infrastructure-as-a-provider offering round gadgets that don’t truly proper into the server play aesthetic. in comparison to a Linux machine from DigitalOcean, it’s now not low priced—at $150 a month for an i3 Mac Mini, you’re now not acquiring this provider by accident. however the company then again has an distinguished locality of interest, underlined with the aid of the indisputable fact that it has patented its own server infrastructure notably designed to cling Mac Minis and Mac professionals, and even has taken steps to attend the iMac seasoned, which has the brought complication of including a reveal that can subsist absolutely unnecessary within the server room.
  • Leaning dainty into virtualization. for those who maintain a necessity to fabricate expend of a Mac every once in a while but don’t are looking to give up their greater common world of home windows or Linux, it’s feasible to expend virtualization equipment, comparable to VirtualBox, to Run a complete Mac set up on their computer, a lot as it’s become ordinary to Run Parallels to bring home windows to the Mac. This approach is technically not allowed by artery of the conclusion consumer License agreement except you’re in fact running it on a Mac, but then once again, most of this different stuff breaks the EULA, too.
  • Leaning complicated into virtualization. extra lately, there was an increased hobby in the usage of low-level hardware virtualization to quite simply change the process of Hackintoshing straight into a bootloader—whatever thing that goes past a simple examine and more into complete system substitute. This approach is just a tiny more straightforward to install than the greater typical Hackintosh route (though nonetheless very technical), and additionally creates less potential risk of blowing up the total desktop. often, this takes the sort of the Linux-based KVM (kernel-primarily based virtual machine), with a hardware virtualization emulator love QEMU managing the equipment image. There are technical merits here: whilst you don’t Get the complete pace of the underlying machine, you Get well-nigh entire of it. moreover, with the confiscate amount of tweaking, it’s feasible to expend peripherals that aren’t entire the time utterly compatible with modern Macs, comparable to Nvidia photos playing cards. There became one user, an employee of MacStadium, who effectively outcome together a working installation of MacOS on KVM that can subsist accessed by means of a cloud-based AMD EPYC device.
  • Why the Hackintosh group can also not appear just love the most welcoming vicinity

    in case you’ve ever requested a tech usher question on the information superhighway, you probably are mindful that usher boards are sometimes overloaded, complete of individuals who inquire obvious questions about their instruments and application.

    Now imagine attempting to present tech champion to individuals who're willingly messing with bootloaders and trying to edit vague device information to fabricate their machine execute whatever thing it technically isn’t designed to do.

    This has led to more aggressive moderation guidelines on one of the most customary forums in Hackintosh-land. Tonymacx86, for instance, is a very effective site for Hackintosh builds, however’s worth noting that the discussion board can speculate a bit of standoffish if you’re novel to it, if simplest as a result of their platform has to contend with a lot of repeated questions. plenty.

    a lot of the time, a Tonymacx86 thread takes a positive shape:

    A user has pretty technical issue that a layperson might not ever fabricate heads or tails of however an authority might possibly subsist capable of spot confiscate away.

    A moderator tells the person they deserve to share their reporting files to spotlight in component what the laptop is going through. additionally, they requisite to examine the FAQ, which is incredibly exact, and that they may silent expend the hunt device, which goes back decades.

    The person responds, both correctly following the suggestions or begging for mercy. in the latter case, they don't Get said mercy frequently and are told to Go read the FAQ once more.

    This goes on and on once in a while for days, and reflects both a exorbitant level of persistence among moderators (critically, kudos), and a wierd vigour dynamic not love any I’ve considered on the internet: In a means, the approach well-nigh discourages the group from getting too huge.

    I requested Chato for his insights on this, and his suggestion, actually, is to RTFM.

    “I speculate the frustration of the ‘specialists’ comes from the fact that many questions arrive from people who maintain not finished any research in any respect or half-study an installation,” he explained. “So, my first bit of suggestions is to research the crap out of what you deserve to understand, examine it all, and then inquire your query.“

    His 2nd piece of guidance deals with motivation: regularly, he notes, these websites maintain a contingent of americans making an attempt to conveniently pirate utility who aren’t doing their analysis, “and they inquire dumb questions on [motherboards] and CPUs which are to this point off the Hackintosh note that it’s just plain insulting.”

    There’s a chasm of varieties within the Apple community, not not love the one that existed when jailbreaking became a extra conventional solemnize among iPhone house owners: Some simply desired to expend the equipment to better their experience, because Apple wasn’t giving them some thing they wanted; others desired a simple artery to Get whatever thing for free.

    “that you may explicate a suitable zealot since it’s obvious they silent personal a Mac,” Chato argued. “They aren’t requesting a pirated distro of the MacOS.”

    Hackintoshing is an thoughtprovoking process as a result of, in circumstances love Chato’s and (admittedly) my very own, it highlights a dichotomy between the company and its supporters: It’s a person base, one technical enough to jump via a lot of hoops, that loves an organization’s product so tons that they’re willing to subvert it to Get that product in its unvarnished kind, since the business’s growth has left them in the back of.

    In 2006, it could were the case that individuals Hackintoshing were trying to experiment or Get a deal. nowadays, I feel there are much more people in this neighborhood who simply requisite Apple to supply them what they requisite on the artery to execute their jobs, after which to Get out of how. These individuals silent want iPhones and iPads, will silent buy Apple accessories, and gladly want to subsist a portion of the enterprise’s ecosystem. but if they could’t Get in the entrance door, fire burned by artery of skinny keyboards and sluggish updates, they’ll Go in during the returned, although there’s greater broken glass on that facet of the constructing.

    consider of it love computing’s version of the “Rural Purge”—that infamous situation where the tv networks determined to reboot their programming to answer the wants of advertisers, who desired younger, city viewers. even if the networks had moved on to Mary Tyler Moore, people silent wanted to watch Lawrence Welk and Hee Haw, so the reveal’s creators institute alternate paths to the airwaves, as well as novel the privilege artery to fabricate a buck. Callous corporate choice-making can’t Kill the interest that readily.

    possibly love these historical Buck Owens and Roy Clark performances, this Hackintosh stuff doesn’t appeal to each person, nevertheless it consists of a niche that cares satisfactory about this platform to disregard the apposite direction and purchase care of the entire minefields that include it.

    In that easy, the sometimes brusque nature of the Hackintosh group is understandable, past americans being sick of rookies. they've an investment to proffer protection to.

    There’s this phenomenon that has defined the manner that the tech community has reacted to things, known as the “Hug of loss of life,” often known as the Slashdot effect.

    virtually, the concept is that this: in case you Run a web site that receives picked up on a well-liked aggregator, so many individuals are recumbent to Go talk over with that it disables your web site absolutely. In a method, it’s an inversion of the Streisand impact, in that its transforming into recognition in reality chokes its success by artery of overexposing it.

    In a means, Hackintosh survives since it’s now not too overexposed. It once in a while shows up on frequent tech YouTube channels love Snazzy Labs and Linus Tech information and frequently gets highlighted in mainstream technology publications, nevertheless it’s whatever that is too tough for a regular Mac consumer to execute and has the adventitious aspect impact of educating Apple about technical concerns that it is asking to preclude in later iterations of its hardware. not ample individuals are hugging it to Kill it just yet.

    bound, there are worries that Apple will expend its T2 safety chip, which it has brought to its recent instruments, to proximate out Hackintosh clients sooner or later, or that the enterprise’s embody of a customized ARM chipset will finally render the Hackintosh out of date. That illustrious it should subsist referred to that some hardware virtualization techniques for the ARM-primarily based iOS already exist, with one being provided by a startup named Corellium. (Corellium’s expend case, centered at cellular builders and protection researchers, was obtained by the boutique hacking store Azimuth security closing yr.)

    As tools love KVM can replicate chipsets love ARM on x86 platforms, it’s now not out of the realm of desultory that options will nonetheless exist if Apple does alternate issues up in a number of years, notwithstanding it adjustments what precisely a Hackintosh is.

    Apple can gain knowledge of technical things from the issues Hackintosh breaks internally, whether by using highlighting flaws internal the kernel or by means of introducing hardware that may additionally ultimately reveal up in a future Apple system, however the existence of this grey-enviornment market within the first region highlights the disparities between Apple’s advertising—skinny and light machines, no matter if on a desk or in a bag—and what its most engaged energy users in fact want.

    “within the conclusion, I don’t suppose Apple trusts the OS,” Chato argues. “That’s what truly bothers me. I don’t feel they recognise that in the event that they outcome MacOS in a pleasant, simple box that doesn’t thermal throttle it's going to promote truly well. It’s the OS, stupid.”

    For a corporation commonly used for its stagy dangers, in entire probability the riskiest current it may fabricate is taking note of this fan groundwork that evidently isn’t served by means of its current offerings.

    It’s no butterfly keyboard mechanism, nevertheless it can subsist a online game changer.

    ZFS-loving Mac clients demand aid in OS X 10.9 | existent Questions and Pass4sure dumps

    ZFS-loving Mac users demand champion
 in OS X 10.9okay Ryan reader comments with 88 posters collaborating, together with legend creator Share this story
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  • Some Mac users are disturbing that Apple add modern file device aid within the subsequent essential version of OS X. an internet petition has been began to let Apple understand that its getting veteran HFS+ file device just won't reduce it to any extent further, and the company should include ZFS in OS X 10.9, anticipated later this yr.

    HFS+ is the existing file gadget used by means of OS X (and iOS). It turned into initially developed as HFS, or "Hierarchical File gadget," for the long-established Mac OS in the early '80s. A crew at Apple, led via engineer Don Brady, tailored HFS for 32-bit methods in the mid-Nineties. Brady later adapted HFS+ to work with the UNIX ambiance that OS X changed into developed on, and over time he and other Apple engineers delivered additional facets, including the extensible metadata used through Mac OS X's highlight search, reside partition resizing used for Boot Camp, and the Adaptive scorching File Clustering used to sever back are searching for times for oft-used device info.

    regardless of the entire features Apple has managed to tack on to HFS+, even though, its design actually isn't modern. "The introductory HFS+ become primarily about addressing the obstruct count problem," Brady instructed Ars in 2011. "considering they believed it turned into most effective a stop-hole solution, they just went from 16 to 32 bits. Had they well-known that it could silent subsist in expend 15 years later with multi-terabyte drives, they likely would maintain finished more design adjustments!"

    ZFS, in spite of this, was designed from the floor up to wield the ever-expanding needs for massive amounts of storage, as neatly as the should protect facts because it is written to and read from disk. As a 128-bit native file equipment, ZFS can address up to a speculative 256 quadrillion zettabytes. One zettabyte on my own is akin to over one thousand million terabytes; 256 quadrillion billion terabytes is greater space for storing than may pretty much subsist used on this planet. It also comprises several points designed to fabricate positive the integrity of statistics on the disk, including checksumming each obstruct of statistics so the gadget is watchful of if a obstruct goes "bad" and RAID-like features that enable disks to "heal" themselves if facts corruption is detected.

    Apple really flirted with ZFS early on in its development. Brady turned into worried in a "skunkworks" assignment to port ZFS to OS X that began in 2005. one of the crucial code shipped in Leopard (10.5) and became expected to subsist a massive characteristic of Snow Leopard (10.6). but due to licensing considerations with sun (and maybe other explanations), Apple dropped entire attend for ZFS in Snow Leopard and cancelled the open source assignment that had served as official aid for ZFS on OS X. (That challenge become forked and nonetheless exists as MacZFS.)

    Brady later left Apple and started his own trade to build a trade edition of ZFS for OS X. He obtained so far as releasing a command line "community" edition called ZEVO earlier than his company changed into received by using commercial enterprise software maker GreenBytes in June 2012. GreenBytes nonetheless presents the free group edition of ZEVO whereas Brady continues to work on a GUI edition that can integrate with OS X (even though restrictions love sandboxing maintain confirmed intricate to work around).

    nonetheless, some users desire respectable attend for ZFS "or its equivalent" from Apple, and that they requisite it soon. Mac user Thomas Monte entire started an online petition virtually demanding that Apple add contemporary filesystem usher to OS X 10.9.

    (The petition additionally asks Apple to replace the ancient OpenGL assist in OS X, which nonetheless lags windows drastically, from edition three.2 to the newest four.three. veteran sources maintain indicated that stronger OpenGL attend is indeed coming.)

    alas, the demand for ZFS champion might also drop on deaf ears. other than the indisputable fact that Apple hasn't shown any indication that it's going to champion anything apart from HFS+ in the meanwhile, OS X 10.9 is already displaying indications that it's being extensively tested internally at Apple. it is also more likely to Get its first public displaying within the subsequent a number of weeks, and if Apple keeps to its projected one-yr evolution cycle, it could subsist released this summer season.

    still, it's been 30 years on the grounds that Apple at the start developed the groundwork for the file gadget at the second utilized in OS X. whether Apple adopts ZFS, Oracle's BtrFS, or is secretly rolling its own contemporary file gadget, OS X is lengthy past due for something new.

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    Mac OS X 10.6 Snow Leopard: the Ars Technica review | existent questions and Pass4sure dumps

    Mac OS X 10.6 Snow Leopard: the Ars Technica review reader comments 454 with 269 posters participating, including legend author Share this story
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  • Mac OS X 10.4 Tiger: 150+ novel featuresMac OS X 10.4 Tiger: 150+ novel features

    In June of 2004, during the WWDC keynote address, Steve Jobs revealed Mac OS X 10.4 Tiger to developers and the public for the first time. When the finished product arrived in April of 2005, Tiger was the biggest, most important, most feature-packed release in the history of Mac OS X by a wide margin. Apple's marketing campaign reflected this, touting "over 150 novel features."

    All those novel features took time. Since its introduction in 2001, there had been at least one major release of Mac OS X each year. Tiger took over a year and a half to arrive. At the time, it definitely seemed worth the wait. Tiger was a hit with users and developers. Apple took the lesson to heart and quickly set expectations for the next major release of Mac OS X, Leopard. Through various channels, Apple communicated its objective to fling from a 12-month to an 18-month release cycle for Mac OS X. Leopard was officially scheduled for "spring 2007."

    As the date approached, Apple's marketing machine trod a predictable path.

    Steve Jobs at WWDC 2007, touting 300 novel features in Mac OS X 10.5 LeopardSteve Jobs at WWDC 2007, touting 300 novel features in Mac OS X 10.5 Leopard

    Apple even went so far as to list entire 300 novel features on its website. As it turns out, "spring" was a bit optimistic. Leopard actually shipped at the abide of October 2007, nearly two and a half years after Tiger. Did Leopard really maintain twice as many novel features as Tiger? That's debatable. What's positive is that Leopard included a solid crop of novel features and technologies, many of which they now purchase for granted. (For example, maintain you had a discussion with a potential Mac user since the release of Leopard without mentioning Time Machine? I certainly haven't.)

    Mac OS X appeared to subsist maturing. The progression was clear: longer release cycles, more features. What would Mac OS X 10.6 subsist like? Would it arrive three and a half years after Leopard? Would it and include 500 novel features? A thousand?

    At WWDC 2009, Bertrand Serlet announced a fling that he described as "unprecedented" in the PC industry.

    Mac OS X 10.6 - Read Bertrand's lips: No novel Features!Mac OS X 10.6 - Read Bertrand's lips: No novel Features!

    That's right, the next major release of Mac OS X would maintain no novel features. The product name reflected this: "Snow Leopard." Mac OS X 10.6 would merely subsist a variant of Leopard. Better, faster, more refined, more... uh... snowy.

    This was a risky strategy for Apple. After the rapid-fire updates of 10.1, 10.2, and 10.3 followed by the riot of novel features and APIs in 10.4 and 10.5, could Apple really Get away with calling a "time out?" I imagine Bertrand was really sweating this announcement up on the stage at WWDC in front of a live audience of Mac developers. Their reaction? impulsive applause. There were even a few hoots and whistles.

    Many of these selfsame developers applauded the "150+ novel features" in Tiger and the "300 novel features" in Leopard at past WWDCs. Now they were applauding zero novel features for Snow Leopard? What explains this?

    It probably helps to know that the "0 novel Features" slip came at the abide of an hour-long presentation detailing the major novel APIs and technologies in Snow Leopard. It was also quickly followed by a back-pedaling ("well, there is one novel feature...") slip describing the addition of Microsoft Exchange support. In isolation, "no novel features" may appear to imply stagnation. In context, however, it served as a developer-friendly affirmation.

    The overall message from Apple to developers was something love this: "We're adding a ton of novel things to Mac OS X that will attend you write better applications and fabricate your existing code Run faster, and we're going to fabricate positive that entire this novel stuff is rock-solid and as bug-free as possible. We're not going to overextend ourselves adding a raft of novel customer-facing, marketing-friendly features. Instead, we're going to concentrate 100% on the things that influence you, the developers."

    But if Snow Leopard is a fancy note to developers, is it a Dear John note to users? You know, those people that the marketing department might so crudely advert to as "customers." What's in it for them? Believe it or not, the sales pitch to users is actually quite similar. As exhausting as it has been for developers to support up with Apple's seemingly never-ending stream of novel APIs, it can subsist just as taxing for customers to abide on top of Mac OS X's features. Exposé, a novel Finder, Spotlight, a novel Dock, Time Machine, a novel Finder again, a novel iLife and iWork almost every year, and on and on. And as much as developers abhor bugs in Apple's APIs, users who undergo those bugs as application crashes maintain just as much intuition to subsist annoyed.

    Enter Snow Leopard: the release where they entire Get a atomize from the new-features/new-bugs treadmill of Mac OS X development. That's the pitch.

    Uncomfortable realities

    But wait a second, didn't I just mention an "hour-long presentation" about Snow Leopard featuring "major novel APIs and technologies?" When speaking to developers, Apple's message of "no novel features" is another artery of aphorism "no novel bugs." Snow Leopard is reputed to fix veteran bugs without introducing novel ones. But nothing says "new bugs, coming privilege up" quite love major novel APIs. So which is it?

    Similarly, for users, "no novel features" connotes stability and reliability. But if Snow Leopard includes enough changes to the core OS to fill an hour-long overview session at WWDC more than a year before its release, can Apple really fabricate pleasurable on this promise? Or will users abide up with entire the disadvantages of a feature-packed release love Tiger or Leopard—the inevitable 10.x.0 bugs, the unfamiliar, untried novel functionality—but without any of the actual novel features?

    Yes, it's enough to fabricate one quite cynical about Apple's existent motivations. To fling some more fuel on the fire, maintain a survey at the Mac OS X release timeline below. Next to each release, I've included a list of its most significant features.

    Mac OS X release timelineMac OS X release timeline

    That curve is taking on a decidedly droopy shape, as if it's being weighed down by the ever-increasing number of novel features. (The releases are distributed uniformly on the Y axis.) Maybe you speculate it's reasonable for the time between releases to stretch out as each one brings a heavier load of goodies than the last, but support in reason the logical consequence of such a curve over the longhorn haul.

    And yeah, there's a tiny upwards kick at the abide for 10.6, but remember, this is reputed to subsist the "no novel features" release. Version 10.1 had a similar no-frills focus but took a heck of a lot less time to arrive.

    Looking at this graph, it's arduous not to sensation if there's something siphoning resources from the Mac OS X evolution effort. Maybe, say, some project that's in the first two or three major releases of its life, silent in that steep, early section of its own timeline graph. Yes, I'm talking about the iPhone, specifically iPhone OS. The iPhone trade has exploded onto Apple's equilibrium sheets love no other product before, even the iPod. It's also accruing developers at an alarming rate.

    It's not a stretch to imagine that many of the artists and developers who piled on the user-visible features in Mac OS X 10.4 and 10.5 maintain been reassigned to iPhone OS (temporarily or otherwise). After all, Mac OS X and iPhone OS share the selfsame core operating system, the selfsame language for GUI development, and many of the selfsame APIs. Some workforce migration seems inevitable.

    And let's not forget the "Mac OS X" technologies that they later learned were developed for the iPhone and just happened to subsist announced for the Mac first (because the iPhone was silent a secret), love Core Animation and code signing. Such collusion theories certainly aren't helped by WWDC keynote snubs and other indignities suffered by Mac OS X and the Mac in general since the iPhone arrived on the scene. And so, on top of everything else, Snow Leopard is tasked with restoring some luster to Mac OS X.

    Got entire that? A nearly two-year evolution cycle, but no novel features. Major novel frameworks for developers, but few novel bugs. Significant changes to the core OS, but more reliability. And a franchise rejuvenation with few user-visible changes.

    It's enough to eddy a leopard white.

    The price of entry

    Snow Leopard's opening overture to consumers is its price: $29 for those upgrading from Leopard. The debut release of Mac OS X 10.0 and the final four major releases maintain entire been $129, with no special pricing for upgrades. After eight years of this kind of fiscal disciplining, Leopard users may well subsist tempted to quit reading privilege now and just Go pick up a copy. Snow Leopard's upgrade price is well under the impulse purchase threshold for many people. Twenty-nine dollars plus some minimal level of faith in Apple's competence to better the OS with each release, and boom, instant purchase.

    Still here? Good, because there's something else you requisite to know about Snow Leopard. It's an overture of a different sort, less of a come-on and more of a spur. Snow Leopard will only Run on Macs with Intel CPUs. Sorry (again), PowerPC fans, but this is the abide of the line for you. The transition to Intel was announced over four years ago, and the final novel PowerPC Mac was released in October 2005. It's time.

    But if Snow Leopard is meant to prod the PowerPC holdouts into the Intel age, its "no novel features" stance (and the accompanying lack of added visual flair) is working against it. For those running Leopard on a PowerPC-based Mac, there's precious tiny in Snow Leopard to attend thrust them over the (likely) four-digit price wall of a novel Mac. For PowerPC Mac owners, the threshold for a novel Mac purchase remains mostly unchanged. When their veteran Mac breaks or seems too slow, they'll Go out and buy a novel one, and it'll arrive with Snow Leopard pre-installed.

    If Snow Leopard does abide up motivating novel Mac purchases by PowerPC owners, it will probably subsist the result of resignation rather than inspiration. An Intel-only Snow Leopard is most significant for what it isn't: a further extension of PowerPC life champion on the Mac platform.

    The final thoughtprovoking group is owners of Intel-based Macs that are silent running Mac OS X 10.4 Tiger. Apple shipped Intel Macs with Tiger installed for a tiny over one year and nine months. Owners of these machines who never upgraded to Leopard are not eligible for the $29 upgrade to Snow Leopard. They're also apparently not eligible to purchase Snow Leopard for the traditional $129 price. Here's what Apple has to snarl about Snow Leopard's pricing (emphasis added).

    Mac OS X version 10.6 Snow Leopard will subsist available as an upgrade to Mac OS X version 10.5 Leopard in September 2009 [...] The Snow Leopard sole user license will subsist available for a suggested retail price of $29 (US) and the Snow Leopard Family Pack, a sole household, five-user license, will subsist available for a suggested price of $49 (US). For Tiger® users with an Intel-based Mac, the Mac Box Set includes Mac OS X Snow Leopard, iLife® '09 and iWork® '09 and will subsist available for a suggested price of $169 (US) and a Family Pack is available for a suggested price of $229 (US).

    Ignoring the family packs for a moment, this means that Snow Leopard will either subsist free with your novel Mac, $29 if you're already running Leopard, or $169 if you maintain an Intel Mac running Tiger. People upgrading from Tiger will Get the latest version of iLife and iWork in the contract (if that's the confiscate term), whether they want them or not. It positive seems love there's an obvious location in this lineup for a $129 offering of Snow Leopard on its own. Then again, perhaps it entire comes down to how, exactly, Apple enforces the $29 Snow Leopard upgrade policy.

    (As an aside to non-Mac users, note that the non-server version of Mac OS X has no per-user serial number and no activation scheme of any kind, and never has. "Registration" with Apple during the Mac OS X install process is entirely optional and is only used to collect demographic information. Failing to register (or entering entirely bogus registration information) has no outcome on your competence to Run the OS. This is considered a genuine edge of Mac OS X, but it also means that Apple has no dependable record of who, exactly, is a "legitimate" owner of Leopard.)

    One possibility was that the $29 Snow Leopard upgrade DVD would only install on top of an existing installation of Leopard. Apple has done this sort of thing before, and it bypasses any proof-of-purchase annoyances. It would, however, interject a novel problem. In the event of a arduous drive failure or simple decision to reinstall from scratch, owners of the $29 Snow Leopard upgrade would subsist forced to first install Leopard and then install Snow Leopard on top of it, perhaps more than doubling the installation time—and quintupling the annoyance.

    Given Apple's history in this area, no one should maintain been surprised to find out that Apple chose the much simpler option: the $29 "upgrade" DVD of Snow Leopard will, in fact, install on any supported Mac, whether or not it has Leopard installed. It will even install onto an entirely blank arduous drive.

    To subsist clear, installing the $29 upgrade to Snow Leopard on a system not already running a properly licensed copy of Leopard is a violation of the end-user license agreement that comes with the product. But Apple's decision is a refreshing change: rewarding honest people with a hassle-free product rather than trying to correct lying people by treating everyone love a criminal. This "honor system" upgrade enforcement policy partially explains the astronomical jump to $169 for the Mac Box Set, which ends up re-framed as an honest person's artery to Get iLife and iWork at their habitual prices, plus Snow Leopard for $11 more.

    And yes, speaking of installing, let's finally Get on with it.


    Apple claims that Snow Leopard's installation process is "up to 45% faster." Installation times vary wildly depending on the speed, contents, and fragmentation of the target disk, the hasten of the optical drive, and so on. Installation also only happens once, and it's not really an thoughtprovoking process unless something goes terribly wrong. Still, if Apple's going to fabricate such a claim, it's worth checking out.

    To purge as many variables as possible, I installed both Leopard and Snow Leopard from one arduous disk onto another (empty) one. It should subsist illustrious that this change negates some of Snow Leopard's most distinguished installation optimizations, which are focused on reducing random data access from the optical disc.

    Even with this disadvantage, the Snow Leopard installation took about 20% less time than the Leopard installation. That's well short of Apple's "up to 45%" claim, but see above (and don't forget the "up to" weasel words). Both versions installed in less than 30 minutes.

    What is striking about Snow Leopard's installation is how quickly the initial Spotlight indexing process completed. Here, Snow Leopard was 74% faster in my testing. Again, the times are tiny (5:49 vs. 3:20) and again, novel installations on blank disks are not the norm. But the shorter wait for Spotlight indexing is worth noting because it's the first indication most users will Get that Snow Leopard means trade when it comes to performance.

    Another notable thing about installation is what's not installed by default: Rosetta, the facility that allows PowerPC binaries to Run on Intel Macs. Okay Apple, they Get it. PowerPC is a stiff, bereft of life. It rests in peace. It's rung down the curtain and joined the choir invisible. As far as Apple is concerned, PowerPC is an ex-ISA.

    But not installing Rosetta by default? That seems a tiny harsh, even foolhardy. What's going to betide when entire those users upgrade to Snow Leopard and then double-click what they've probably long since forgotten is a PowerPC application? Perhaps surprisingly, this is what happens:

    Rosetta: auto-installed for your convenienceRosetta: auto-installed for your convenience

    That's what I saw when I tried to launch Disk Inventory X on Snow Leopard, an application that, yes, I had long since forgotten was PowerPC-only. After I clicked the "Install" button, I actually expected to subsist prompted to insert the installer DVD. Instead, Snow Leopard reached out over the network, pulled down Rosetta from an Apple server, and installed it.

    Rosetta auto-install

    No reboot was required, and Disk Inventory X launched successfully after the Rosetta installation completed. Mac OS X has not historically made much expend of the install-on-demand approach to system software components, but the facility used to install Rosetta appears quite robust. Upon clicking "Install," an XML property list containing a vast catalog of available Mac OS X packages was downloaded. Snow Leopard uses the selfsame facility to download and install printer drivers on demand, saving another trip to the installer DVD. I hope this technique gains even wider expend in the future.

    Installation footprint

    Rosetta aside, Snow Leopard simply puts fewer bits on your disk. Apple claims it "takes up less than half the disk space of the previous version," and that's no lie. A clean, default install (including fully-generated Spotlight indexes) is 16.8 GB for Leopard and 5.9 GB for Snow Leopard. (Incidentally, these numbers are both powers-of-two measurements; see sidebar.)

    A gigabyte by any other name

    Snow Leopard has another trick up its sleeve when it comes to disk usage. The Snow Leopard Finder considers 1 GB to subsist equal to 109 (1,000,000,000) bytes, whereas the Leopard Finder—and, it should subsist noted, every version of the Finder before it—equates 1 GB to 230 (1,073,741,824) bytes. This has the outcome of making your arduous disk suddenly issue larger after installing Snow Leopard. For example, my "1 TB" arduous drive shows up in the Leopard Finder as having a capacity of 931.19 GB. In Snow Leopard, it's 999.86 GB. As you might maintain guessed, arduous disk manufacturers expend the powers-of-ten system. It's entire quite a mess, really. Though I arrive down pretty firmly on the powers-of-two side of the fence, I can't blame Apple too much for wanting to match up nicely with the long-established (but silent dumb, reason you) arduous disk vendors' capacity measurement standard.

    Snow Leopard has several weight loss secrets. The first is obvious: no PowerPC champion means no PowerPC code in executables. Recall the maximum feasible binary payload in a Leopard executable: 32-bit PowerPC, 64-bit PowerPC, x86, and x86_64. Now cross half of those architectures off the list. Granted, very few applications in Leopard included 64-bit code of any kind, but it's a 50% reduction in size for executables no matter how you slice it.

    Of course, not entire the files in the operating system are executables. There are data files, images, audio files, even a tiny video. But most of those non-executable files maintain one thing in common: they're usually stored in compressed file formats. Images are PNGs or JPEGs, audio is AAC, video is MPEG-4, even preference files and other property lists now default to a compact binary format rather than XML.

    In Snow Leopard, other kinds of files climb on board the compression bandwagon. To give just one example, ninety-seven percent of the executable files in Snow Leopard are compressed. How compressed? Let's look:

    % cd Applications/ % ls -l Mail -rwxr-xr-x@ 1 root wheel 0 Jun 18 19:35 Mail

    Boy, that's, uh, pretty small, huh? Is this really an executable or what? Let's check their assumptions.

    % file Applications/ Applications/ empty

    Yikes! What's going on here? Well, what I didn't explicate you is that the commands shown above were Run from a Leopard system looking at a Snow Leopard disk. In fact, entire compressed Snow Leopard files issue to hold zero bytes when viewed from a pre-Snow Leopard version of Mac OS X. (They survey and act perfectly traditional when booted into Snow Leopard, of course.)

    So, where's the data? The tiny "@" at the abide of the permissions string in the ls output above (a feature introduced in Leopard) provides a clue. Though the Mail executable has a zero file size, it does maintain some extended attributes:

    % xattr -l Applications/ 0000 00 00 01 00 00 2C F5 F2 00 2C F4 F2 00 00 00 32 .....,...,.....2 0010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ (184,159 lines snipped) 2CF610 63 6D 70 66 00 00 00 0A 00 01 FF FF 00 00 00 00 cmpf............ 2CF620 00 00 00 00 .... 0000 66 70 6D 63 04 00 00 00 A0 82 72 00 00 00 00 00 fpmc......r.....

    Ah, there's entire the data. But wait, it's in the resource fork? Weren't those deprecated about eight years ago? Indeed they were. What you're witnessing here is yet another addition to Apple's favorite file system hobbyhorse, HFS+.

    At the dawn of Mac OS X, Apple added journaling, symbolic links, and arduous links. In Tiger, extended attributes and access control lists were incorporated. In Leopard, HFS+ gained champion for arduous links to directories. In Snow Leopard, HFS+ learns another novel trick: per-file compression.

    The presence of the impute is the first hint that this file is compressed. This impute is actually hidden from the xattr command when booted into Snow Leopard. But from a Leopard system, which has no knowledge of its special significance, it shows up as plain as day.

    Even more information is revealed with the attend of Mac OS X Internals guru Amit Singh's hfsdebug program, which has quietly been updated for Snow Leopard.

    % hfsdebug /Applications/ ... compression magic = cmpf compression sort = 4 (resource fork has compressed data) uncompressed size = 7500336 bytes

    And positive enough, as they saw, the resource fork does indeed hold the compressed data. Still, why the resource fork? It's entire portion of Apple's usual, clever backward-compatibility gymnastics. A recent case is the artery that arduous links to directories reveal up—and function—as aliases when viewed from a pre-Leopard version of Mac OS X.

    In the case of a HFS+ compression, Apple was (understandably) unable to fabricate pre-Snow Leopard systems read and interpret the compressed data, which is stored in ways that did not exist at the time those earlier operating systems were written. But rather than letting applications (and users) running on pre-10.6 systems choke on—or worse, debase through modification—the unexpectedly compressed file contents, Apple has chosen to mask the compressed data instead.

    And where can the complete contents of a potentially great file subsist hidden in such a artery that pre-Snow Leopard systems can silent copy that file without the loss of data? Why, in the resource fork, of course. The Finder has always correctly preserved Mac-specific metadata and both the resource and data forks when stirring or duplicating files. In Leopard, even the lowly cp and rsync commands will execute the same. So while it may subsist a tiny bit spooky to see entire those "empty" 0 KB files when looking at a Snow Leopard disk from a pre-Snow Leopard OS, the desultory of data loss is small, even if you fling or copy one of the files.

    The resource fork isn't the only location where Apple has decided to smuggle compressed data. For smaller files, hfsdebug shows the following:

    % hfsdebug /etc/asl.conf ... compression magic = cmpf compression sort = 3 (xattr has compressed data) uncompressed size = 860 bytes

    Here, the data is tiny enough to subsist stored entirely within an extended attribute, albeit in compressed form. And then, the final frontier:

    % hfsdebug /Volumes/Snow Time/Applications/ ... compression magic = cmpf compression sort = 3 (xattr has inline data) uncompressed size = 8 bytes

    That's right, an entire file's contents stored uncompressed in an extended attribute. In the case of a benchmark PkgInfo file love this one, those contents are the four-byte classic Mac OS sort and creator codes.

    % xattr -l Applications/ 0000 66 70 6D 63 03 00 00 00 08 00 00 00 00 00 00 00 fpmc............ 0010 FF 41 50 50 4C 65 6D 61 6C .APPLemal

    There's silent the selfsame "fpmc..." preamble seen in entire the earlier examples of the attribute, but at the abide of the value, the expected data appears as plain as day: sort code "APPL" (application) and creator code "emal" (for the Mail application—cute, as per classic Mac OS tradition).

    You may subsist wondering, if this is entire about data compression, how does storing eight uncompressed bytes plus a 17-byte preamble in an extended impute reclaim any disk space? The respond to that lies in how HFS+ allocates disk space. When storing information in a data or resource fork, HFS+ allocates space in multiples of the file system's allocation obstruct size (4 KB, by default). So those eight bytes will purchase up a minimum of 4,096 bytes if stored in the traditional way. When allocating disk space for extended attributes, however, the allocation obstruct size is not a factor; the data is packed in much more tightly. In the end, the actual space saved by storing those 25 bytes of data in an extended impute is over 4,000 bytes.

    But compression isn't just about saving disk space. It's also a classic case of trading CPU cycles for decreased I/O latency and bandwidth. Over the past few decades, CPU performance has gotten better (and computing resources more plentiful—more on that later) at a much faster rate than disk performance has increased. Modern arduous disk quest times and rotational delays are silent measured in milliseconds. In one millisecond, a 2 GHz CPU goes through two million cycles. And then, of course, there's silent the actual data transfer time to consider.

    Granted, several levels of caching throughout the OS and hardware work mightily to mask these delays. But those bits maintain to arrive off the disk at some point to fill those caches. Compression means that fewer bits maintain to subsist transferred. Given the almost comical glut of CPU resources on a modern multi-core Mac under traditional use, the total time needed to transfer a compressed payload from the disk and expend the CPU to decompress its contents into reminiscence will silent usually subsist far less than the time it'd purchase to transfer the data in uncompressed form.

    That explains the potential performance benefits of transferring less data, but the expend of extended attributes to store file contents can actually fabricate things faster, as well. It entire has to execute with data locality.

    If there's one thing that slows down a arduous disk more than transferring a great amount of data, it's stirring its heads from one portion of the disk to another. Every fling means time for the head to start moving, then stop, then ensure that it's correctly positioned over the desired location, then wait for the spinning disk to outcome the desired bits beneath it. These are entire real, physical, stirring parts, and it's improbable that they execute their dance as quickly and efficiently as they do, but physics has its limits. These motions are the existent performance killers for rotational storage love arduous disks.

    The HFS+ volume format stores entire its information about files—metadata—in two primary locations on disk: the Catalog File, which stores file dates, permissions, ownership, and a host of other things, and the Attributes File, which stores "named forks."

    Extended attributes in HFS+ are implemented as named forks in the Attributes File. But unlike resource forks, which can subsist very great (up to the maximum file size supported by the file system), extended attributes in HFS+ are stored "inline" in the Attributes File. In practice, this means a restrict of about 128 bytes per attribute. But it also means that the disk head doesn't requisite to purchase a trip to another portion of the disk to Get the actual data.

    As you can imagine, the disk blocks that fabricate up the Catalog and Attributes files are frequently accessed, and therefore more likely than most to subsist in a cache somewhere. entire of this conspires to fabricate the complete storage of a file, including both its metadata in its data, within the B-tree-structured Catalog and Attributes files an overall performance win. Even an eight-byte payload that balloons to 25 bytes is not a concern, as long as it's silent less than the allocation obstruct size for traditional data storage, and as long as it entire fits within a B-tree node in the Attributes File that the OS has to read in its entirety anyway.

    There are other significant contributions to Snow Leopard's reduced disk footprint (e.g., the removal of unnecessary localizations and "designable.nib" files) but HFS+ compression is by far the most technically interesting.

    Installer intelligence

    Apple makes two other thoughtprovoking promises about the installation process:

    Snow Leopard checks your applications to fabricate positive they're compatible and sets aside any programs known to subsist incompatible. In case a power outage interrupts your installation, it can start again without losing any data.

    The setting aside of "known incompatible" applications is undoubtedly a response to the "blue screen" problems some users encountered when upgrading from Tiger to Leopard two years ago, which was caused by the presence of incompatible—and some would snarl "illicit"—third-party system extensions. I maintain a decidedly pragmatic view of such software, and I'm glad to see Apple taking a similarly practical approach to minimizing its impact on users.

    Apple can't subsist expected to detect and disable entire potentially incompatible software, of course. I suspect only the most common or highest profile risky software is detected. If you're a developer, this installer feature may subsist a pleasurable artery to find out if you're on Apple's sh*t list.

    As for continuing an installation after a power failure, I didn't maintain the guts to test this feature. (I also maintain a UPS.) For long-running processes love installation, this kind of added robustness is welcome, especially on battery-powered devices love laptops.

    I mention these two details of the installation process mostly because they highlight the kinds of things that are feasible when developers at Apple are given time to polish their respective components of the OS. You might speculate that the installer team would subsist hard-pressed to arrive up with enough to execute during a nearly two-year evolution cycle. That's clearly not the case, and customers will reap the benefits.

    Snow Leopard's novel looks

    I've long yearned for Apple to fabricate a antiseptic break, at least visually, from Mac OS X's Aqua past. Alas, I will subsist waiting a bit longer, because Snow Leopard ushers in no such revolution. And yet here I am, beneath a familiar-looking section heading that seems to indicate otherwise. The verity is, Snow Leopard actually changes the appearance of nearly every pixel on your screen—but not in the artery you might imagine.

    Since the dawn of color on the Macintosh, the operating system has used a default output gamma correction value of 1.8. Meanwhile, Windows—aka the rest of the world—has used a value of 2.2. Though this may not appear significant to anyone but professional graphics artists, the dissimilarity is usually plain to even a casual observer when viewing the selfsame image on both kinds of displays side by side.

    Though Mac users will probably instinctively prefer the 1.8 gamma image that they're used to, Apple has decided that this historical dissimilarity is more pain than it's worth. The default output gamma correction value in Snow Leopard is now 2.2, just love everyone else. Done and done.

    If they notice at all, users will likely undergo this change as a fire that the Snow Leopard user interface has a bit more contrast than Leopard's. This is reinforced by the novel default desktop background, a re-drawn, more saturated version of Leopard's default desktop. (Note that these are two entirely different images and not an attempt to demonstrate the effects of different gamma correction settings.)

    LeopardLeopard Snow LeopardSnow Leopard Dock Exposé spotlight effectDock Exposé spotlight effect

    But even beyond color correction, suitable to form, Apple could not resist adding a few graphical tweaks to the Snow Leopard interface. The most plain changes are related to the Dock. First, there's the novel "spotlight" survey triggered by a click-and-hold on an application icon in the Dock. (This activates Exposé, but only for the windows belonging to the application that was clicked. More later.)

    Furthermore, any and entire pop-up menus on the Dock—and only on the Dock—have a unique survey in Snow Leopard, complete with a custom selection appearance (which, for a change, does a passable job of matching the system-wide selection appearance setting).

    New Dock menu appearance. Mmmm… arbitrary.New Dock menu appearance. Mmmm… arbitrary.

    For Mac users of a positive age, these menus may bring to reason Apple's Hi-Tech appearance theme from the bad-old days of Copland. They're actually considerably more subtle, however. Note the translucent edges which accentuate the rounded corners. The gradient on the selection highlight is also admirably restrained.

    Nevertheless, this is an entirely novel survey for a sole (albeit commonly used) application, and it does clash a bit with the default "slanty, shiny shelf" appearance of the Dock. But I've already had my snarl about that, and more. If the oath of Snow Leopard's appearance was to "first, execute no harm," then I speculate I'm inclined to give it a passing grade—almost.

    If I had to characterize what's wrong with Snow Leopard's visual additions with just two words, it'd subsist these: everything fades. Apple has sprinkled Core Animation fairy dust over seemingly every application in Snow Leopard. If any portion of the user interface appears, disappears, or changes in any significant way, it's accompanied by an animation and one or more fades.

    In moderation, such effects are fine. But in several instances, Snow Leopard crosses the line. Or rather, it crosses my line, which, it should subsist noted, is located far inside the territories of Candy Land. Others with a much lower tolerance for animations who are already galled by the frippery in Leopard and earlier releases will find tiny to fancy in Snow Leopard's visual changes.

    The one that really drove me over the edge is the fussy tiny dance of the filename locality that occurs in the Finder (surprise!) when renaming a file on the desktop. There's just something about so many cross-fades, color changes, and text offsets occurring so rapidly and concentrated into such a tiny locality that makes me want to scream. And whether or not I'm actually waiting for these animations to finish before I can continue to expend my computer, it certainly feels that artery sometimes.

    Still, I must unenthusiastically forecast that most traditional people (i.e., the ones who will not read this entire article) will either find these added visual touches delightful, or (much more likely) not notice them at all.


    Animation aside, the visual sameness of Snow Leopard presents a bit of a marketing challenge for Apple. Even beyond the obvious problem of how to promote an operating system upgrade with "no novel features" to consumers, there's the issue of how to Get people to notice that this novel product exists at all.

    In the run-up to Snow Leopard's release, Apple stuck to a modified version of Leopard's outer space theme. It was in the keynote slideshows, on the WWDC banners, on the developer release DVDs, and entire over the Mac OS X section of Apple's website. The header image from Apple's Mac OS X webpage as of a week before Snow Leopard's release appears below. It's pretty sever and dried: outer space, stars, wealthy purple nebula, lens flare.

    Snow. The final frontier.Snow. The final frontier.

    Then came the golden master of Snow Leopard, which, in a pleasant change from past releases, was distributed to developers a few weeks before Snow Leopard hit the shelves. Its installer introduced an entirely different survey which, as it turns out, was carried over to the retail packaging. For a change, let's line up the discs instead of the packaging (which is rapidly shrinking to barely coop the disc anyway). Here's Mac OS X 10.0 through 10.6, top to bottom and left to right. (The 10.0 and 10.1 discs looked essentially identical and maintain been coalesced.)

    One of these things is not love the others…One of these things is not love the others…

    Yep, it's a snow leopard. With actual snow on it. It's a bit on the nose for my taste, but it's not without its charms. And it does maintain one astronomical thing going for it: it's immediately recognizable as something novel and different. "Unmistakable" is how I'd sum up the packaging. Eight years of the giant, centered, variously adorned "X" and then boom: a cat. There's tiny desultory that anyone who's seen Leopard sitting on the shelf of their local Apple store for the past two years will fail to notice that this is a novel product.

    (If you'd love your own picture of Snowy the snow leopard (that's right, I've named him), Apple was kind enough to include a desktop background image with the OS. Self-loathing Windows users may download it directly.)

    Warning: internals ahead

    We've arrived at the start of the customary "internals" section. Snow Leopard is entire about internal changes, and this is reflected in the content of this review. If you're only interested in the user-visible changes, you can skip ahead, but you'll subsist missing out on the meat of this review and the heart of Apple's novel OS.

    64-bit: the road leads ever on

    Mac OS X started its journey to 64-bit back in 2003 with the release of Panther, which included the bare minimum champion for the then-new PowerPC G5 64-bit CPU. In 2005, Tiger brought with it the competence to create suitable 64-bit processes—as long as they didn't link with any of the GUI libraries. Finally, Leopard in 2007 included champion for 64-bit GUI applications. But again, there was a caveat: 64-bit champion extended to Cocoa applications only. It was, effectively, the abide of the road for Carbon.

    Despite Leopard's seemingly impressive 64-bit bona fides, there are a few more steps before Mac OS X can achieve complete 64-bit nirvana. The diagrams below illustrate.

    64-bit in Mac OS X 10.4 Tiger 64-bit in Mac OS X 10.5 Leopard 64-bit in Mac OS X 10.6 Snow Leopard Mac OS X 10.4 Tiger Mac OS X 10.5 Leopard Mac OS X 10.6 Snow Leopard

    As we'll see, entire that yellow in the Snow Leopard diagram represents its capability, not necessarily its default mode of operation.


    Snow Leopard is the first version of Mac OS X to ship with a 64-bit kernel ("K64" in Apple's parlance), but it's not enabled by default on most systems. The intuition for this this is simple. Recall that there's no "mixed mode" in Mac OS X. At runtime, a process is either 32-bit or 64-bit, and can only load other code—libraries, plug-ins, etc.—of the selfsame kind.

    An distinguished class of plug-ins loaded by the kernel is device drivers. Were Snow Leopard to default to the 64-bit kernel, only 64-bit device drivers would load. And seeing as Snow Leopard is the first version of Mac OS X to include a 64-bit kernel, there'd subsist precious few of those on customers' systems on launch day.

    And so, by default, Snow Leopard boots with a 64-bit kernel only on Xserves from 2008 or later. I guess the assumption is that entire of the devices commonly attached to an Xserve will subsist supported by 64-bit drivers supplied by Apple in Snow Leopard itself.

    Perhaps surprisingly, not entire Macs with 64-bit processors are even able to boot into the 64-bit kernel. Though this may change in subsequent point releases of Snow Leopard, the table below lists entire the Macs that are either capable of or default to booting K64. (To find the "Model name" of your Mac, select "About This Mac" from the Apple menu, then click the "More info…" button and read the "Model Identifier" line in the window that appears.)

    Product Model name K64 status Early 2008 Mac Pro MacPro3,1 Capable Early 2008 Xserve Xserve2,1 Default MacBook Pro 15"/17" MacBookPro4,1 Capable iMac iMac8,1 Capable UniBody MacBook Pro 15" MacBookPro5,1 Capable UniBody MacBook Pro 17" MacBookPro5,2 Capable Mac Pro MacPro4,1 Capable iMac iMac9,1 Capable Early 2009 Xserve Xserve3,1 Default

    For entire K64-capable Macs, boot while holding down "6" and "4" keys simultaneously to select the 64-bit kernel. For a more permanent solution, expend the nvram command to add arch=x86_64 to your boot-args string, or edit the file /Library/Preferences/SystemConfiguration/ and add arch=x86_64 to the Kernel Flags string:

    ... <key>Kernel</key> <string>mach_kernel</string> <key>Kernel Flags</key> <string>arch=x86_64</string> ...

    To switch back to the 32-bit kernel, hold down the "3" and "2" keys during boot, or expend one of the techniques above, replacing "x86_64" with "i386".

    We've already discussed why, at least initially, you probably won't want to boot into K64. But as Snow Leopard adoption ramps up and 64-bit updates of existing kernel extensions become available, why might you actually want to expend the 64-bit kernel?

    The first intuition has to execute with RAM, and not in the artery you might think. Though Leopard uses a 32-bit kernel, Macs running Leopard can hold and expend far more RAM than the 4 GB restrict the "32-bit" qualifier might appear to imply. But as RAM sizes increase, there's another concern: address space depletion—not for applications, but for the kernel itself.

    As a 32-bit process, the kernel itself is limited to a 32-bit (i.e., 4GB) address space. That may not appear love a problem; after all, should the kernel really requisite more than 4GB of reminiscence to execute its job? But recollect that portion of the kernel's job is to track and manage system memory. The kernel uses a 64-byte structure to track the status of each 4KB page of RAM used on the system.

    That's 64 bytes, not kilobytes. It hardly seems love a lot. But now regard a Mac in the not-too-distant future containing 96GB of RAM. (If this sounds ridiculous to you, speculate of how ridiculous the 8GB of RAM in the Mac I'm typing on privilege now would maintain sounded to you five years ago.) Tracking 96GB of RAM requires 1.5GB of kernel address space. Using more than a third of the kernel's address space just to track reminiscence is a pretty uncomfortable situation.

    A 64-bit kernel, on the other hand, has a virtually unlimited kernel address space (16 exabytes). K64 is an inevitable necessity, given the rapidly increasing size of system memory. Though you may not requisite it today on the desktop, it's already common for servers to maintain double-digit gigabytes of RAM installed.

    The other thing K64 has going for it is speed. The x86 instruction set architecture has had a bit of a tortured history. When designing the x86-64 64-bit extension of the x86 architecture, AMD took the break to leave behind some of the ugliness of the past and include more modern features: more registers, novel addressing modes, non-stack-based floating point capabilities, etc. K64 reaps these benefits. Apple makes the following claims about its performance:

  • 250% faster system summon entry point
  • 70% faster user/kernel reminiscence copy
  • Focused benchmarking would bear these out, I'm sure. But in daily use, you're unlikely to subsist able to impute any particular performance boost to the kernel. speculate of K64 as removing bottlenecks from the few (usually server-based) applications that actually execute exercise these aspects of the kernel heavily.

    If it makes you feel better to know that your kernel is operating more efficiently, and that, were you to actually maintain 96GB of RAM installed, you would not risk starving the kernel of address space, and if you don't maintain any 32-bit drivers that you absolutely requisite to use, then by entire means, boot into the 64-bit kernel.

    For everyone else, my advice is to subsist glad that K64 will subsist ready and waiting for you when you eventually execute requisite it—and gladden execute encourage entire the vendors that fabricate kernel extensions that you care about to add K64 champion as soon as possible.

    Finally, this is worth repeating: gladden support in reason that you execute not requisite to Run the 64-bit kernel in order to Run 64-bit applications or install more than 4GB of RAM in your Mac. Applications Run just fine in 64-bit mode on top of the 32-bit kernel, and even in earlier versions of Mac OS X it's been feasible to install and purchase edge of much more than 4GB of RAM.

    64-bit applications

    While Leopard may maintain brought with it champion for 64-bit GUI applications, it actually included very few of them. In fact, by my count, only two 64-bit GUI applications shipped with Leopard: Xcode (an optional install) and Chess. And though Leopard made it feasible for third-party developers to produce 64-bit (albeit Leopard-only) GUI applications, very few have—sometimes due to unfortunate realities, but most often because there's been no pleasurable intuition to execute so, abandoning users of Mac OS X 10.4 or earlier in the process.

    Apple is now pushing the 64-bit transition much harder. This starts with leading by example. Snow Leopard ships with four end-user GUI applications that are not 64-bit: iTunes, Grapher, Front Row, and DVD Player. Everything else is 64-bit. The Finder, the Dock, Mail, TextEdit, Safari, iChat, Address Book, Dashboard, attend Viewer, Installer, Terminal, Calculator—you name it, it's 64-bit.

    The second astronomical carrot (or stick, depending on how you survey at it) is the continued lack of 32-bit champion for novel APIs and technologies. Leopard started the trend, leaving deprecated APIs behind and only porting the novel ones to 64-bit. The improved Objective-C 2.0 runtime introduced in Leopard was also 64-bit-only.

    Snow Leopard continues along similar lines. The Objective-C 2.1 runtime's non-fragile instance variables, exception model unified with C++, and faster vtable dispatch remain available only to 64-bit applications. But the most significant novel 64-bit-only API is QuickTime X—significant enough to subsist addressed separately, so abide tuned.

    64-bits or bust

    All of this is Apple's not-so-subtle artery of telling developers that the time to fling to 64-bit is now, and that 64-bit should subsist the default for entire novel applications, whether a developer thinks it's "needed" or not. In most cases, these novel APIs maintain no intrinsic connection to 64-bit. Apple has simply chosen to expend them as additional forms of persuasion.

    Despite entire of the above, I'd silent summon Snow Leopard merely the penultimate step in Mac OS X's journey to subsist 64-bit from top to bottom. I fully expect Mac OS X 10.7 to boot into the 64-bit kernel by default, to ship with 64-bit versions of entire applications, plug-ins, and kernel extensions, and to leave even more legacy and deprecated APIs to fade away in the land of 32-bit.

    QuickTime X

    Apple did something a bit odd in Leopard when it neglected to port the C-based QuickTime API to 64-bit. At the time, it didn't appear love such a astronomical deal. Mac OS X's transition to 64-bit had already spanned many years and several major versions. One could imagine that it just wasn't yet QuickTime's eddy to Go 64-bit.

    As it turns out, my terse but pessimistic assessment of the situation at the time was accurate: QuickTime got the "Carbon treatment". love Carbon, the venerable QuickTime API that they know and fancy will not subsist making the transition to 64-bit—ever.

    To subsist clear, QuickTime the technology and QuickTime the brand will most definitely subsist coming to 64-bit. What's being left behind in 32-bit-only form is the C-based API introduced in 1991 and built upon for 18 years thereafter. Its replacement in the world of 64-bit in Snow Leopard is the aptly named QuickTime X.

    The "X" in QuickTime X, love the one in in Mac OS X, is pronounced "ten." This is but the first of many eerie parallels. love Mac OS X before it, QuickTime X:

  • aims to fabricate a antiseptic atomize from its predecessor
  • is based on technology originally developed for another platform
  • includes transparent compatibility with its earlier incarnation
  • promises better performance and a more modern architecture
  • lacks many distinguished features in its initial release
  • Maximum available Mac CPU hasten (MHz)Maximum available Mac CPU hasten (MHz)

    Let's purchase these one at a time. First, why is a antiseptic atomize needed? outcome simply, QuickTime is old—really old. The horribly blocky, postage-stamp-size video displayed by its initial release in 1991 was considered a technological tour de force.

    At the time, the fastest Macintosh money could buy contained a 25 MHz CPU. The ridiculous chart to the privilege is meant to hammer home this point. Forward-thinking design can only Get you so far. The shape of the world a technology is born into eventually, inevitably dictates its fate. This is especially suitable for long-lived APIs love QuickTime with a tough bent towards backward compatibility.

    As the first successful implementation of video on a personal computer, it's frankly improbable that the QuickTime API has lasted as long as it has. But the world has moved on. Just as Mac OS institute itself mired in a ghetto of cooperative multitasking and unprotected memory, QuickTime limps into 2009 with antiquated notions of concurrency and subsystem layering baked into its design.

    When it came time to write the video-handling code for the iPhone, the latest version of QuickTime, QuickTime 7, simply wasn't up to the task. It had grown too bloated and inefficient during its life on the desktop, and it lacked pleasurable champion for the GPU-accelerated video playback necessary to wield modern video codecs on a handheld (even with a CPU sixteen times the clock hasten of any available in a Mac when QuickTime 1.0 was released). And so, Apple created a tight, modern, GPU-friendly video playback engine that could proper comfortably within the RAM and CPU constraints of the iPhone.

    Hmm. An aging desktop video API in requisite of a replacement. A fresh, novel video library with pleasurable performance even on (comparatively) anemic hardware. Apple connected the dots. But the trick is always in the transition. Happily, this is Apple's forte. QuickTime itself has already lived on three different CPU architectures and three entirely different operating systems.

    The switch to 64-bit is yet another (albeit less dramatic) inflection point, and Apple has chosen it to note the limit between the veteran QuickTime 7 and the novel QuickTime X. It's done this in Snow Leopard by limiting entire expend of QuickTime by 64-bit applications to the QTKit Objective-C framework.

    QTKit's novel world order

    QTKit is not new; it began its life in 2005 as a more native-feeling interface to QuickTime 7 for Cocoa applications. This extra layer of abstraction is the key to the QuickTime X transition. QTKit now hides within its object-oriented walls both QuickTime 7 and QuickTime X. Applications expend QTKit as before, and behind the scenes QTKit will elect whether to expend QuickTime 7 or QuickTime X to fulfill each request.

    If QuickTime X is so much better, why doesn't QTKit expend it for everything? The respond is that QuickTime X, love its Mac OS X namesake, has very limited capabilities in its initial release. While QuickTime X supports playback, capture, and exporting, it does not champion general-purpose video editing. It also supports only "modern" video formats—basically, anything that can subsist played by an iPod, iPhone, or Apple TV. As for other video codecs, well, you can forget about handling them with plug-ins because QuickTime X doesn't champion those either.

    For every one of the cases where QuickTime X is not up to the job, QuickTime 7 will fill in. Cutting, copying, and pasting portions of a video? QuickTime 7. Extracting individual tracks from a movie? QuickTime 7. Playing any movie not natively supported by an existing Apple handheld device? QuickTime 7. Augmenting QuickTime's codec champion using a plug-in of any kind? You guessed it: QuickTime 7.

    But wait a second. If QTKit is the only artery for a 64-bit application to expend QuickTime, and QTKit multiplexes between QuickTime 7 and QuickTime X behind the scenes, and QuickTime 7 is 32-bit-only, and Mac OS X does not champion "mixed mode" processes that can execute both 32-bit and 64-bit code, then how the heck does a 64-bit process execute anything that requires the QuickTime 7 back-end?

    To find out, fire up the novel 64-bit QuickTime Player application (which will subsist addressed separately later) and open a movie that requires QuickTime 7. Let's say, one that uses the Sorenson video codec. (Remember that? pleasurable times.) positive enough, it plays just fine. But search for "QuickTime" in the Activity Monitor application and you'll see this:

    Pretty sneaky, sis: 32-bit QTKitServer processPretty sneaky, sis: 32-bit QTKitServer process

    And the respond is revealed. When a 64-bit application using QTKit requires the services of the 32-bit-only QuickTime 7 back-end, QTKit spawns a divorce 32-bit QTKitServer process to execute the work and communicate the results back to the originating 64-bit process. If you leave Activity Monitor open while using the novel QuickTime Player application, you can watch the QTKitServer processes arrive and Go as needed. This is entire handled transparently by the QTKit framework; the application itself requisite not subsist watchful of these machinations.

    Yes, it's going to subsist a long, long time before QuickTime 7 disappears completely from Mac OS X (at least Apple was kind enough not to summon it "QuickTime Classic"), but the path forward is clear. With each novel release of Mac OS X, expect the capabilities of QuickTime X to expand, and the number of things that silent require QuickTime 7 to decrease. In Mac OS X 10.7, for example, I imagine that QuickTime X will gain champion for plug-ins. And surely by Mac OS X 10.8, QuickTime X will maintain complete video editing support. entire this will subsist happening beneath the unifying facade of QTKit until, eventually, the QuickTime 7 back-end is no longer needed at all.

    Say what you mean

    In the meantime, perhaps surprisingly, many of the current limitations of QuickTime X actually highlight its unique advantages and inform the evolving QTKit API. Though there is no direct artery for a developer to request that QTKit expend the QuickTime X back-end, there are several indirect means to influence the decision. The key is the QTKit API, which relies heavily on the concept of intent.

    QuickTime versions 1 through 7 expend a sole representation of entire media resources internally: a Movie object. This representation includes information about the individual tracks that fabricate up the movie, the sample tables for each track, and so on—all the information QuickTime needs to understand and maneuver the media.

    This sounds powerful until you realize that to execute anything with a media resource in QuickTime requires the construction of this comprehensive Movie object. regard playing an MP3 file with QuickTime, for example. QuickTime must create its internal Movie kick representation of the MP3 file before it can originate playback. Unfortunately, the MP3 container format seldom contains comprehensive information about the structure of the audio. It's usually just a stream of packets. QuickTime must laboriously scan and parse the entire audio stream in order to complete the Movie object.

    QuickTime 7 and earlier versions fabricate this process less painful by doing the scanning and parsing incrementally in the background. You can see this in many QuickTime-based player applications in the form of a progress bar overlaid on the movie controller. The image below shows a 63MB MP3 podcast loading in the Leopard version of QuickTime Player. The shaded portion of the movie timeline slowly fills the dotted locality from left to right.

    QuickTime 7 doing more work than necessary

    QuickTime 7 doing more work than necessary

    Though playback can originate almost immediately (provided you play from the beginning, that is) it's worthwhile to purchase a step back and regard what's going on here. QuickTime is creating a Movie kick suitable for any operation that QuickTime can perform: editing, track extraction or addition, exporting, you name it. But what if entire I want to execute is play the file?

    The pain is, the QuickTime 7 API lacks a artery to express this kind of intent. There is no artery to snarl to QuickTime 7, "Just open this file as quickly as feasible so that I can play it. Don't bother reading every sole byte of the file from the disk and parsing it to determine its structure just in case I resolve to edit or export the content. That is not my intent. Please, just open it for playback."

    The QTKit API in Snow Leopard provides exactly this capability. In fact, the only artery to subsist eligible for the QuickTime X back-end at entire is to explicitly express your intent not to execute anything QuickTime X cannot handle. Furthermore, any attempt to discharge an operation that lies outside your previously expressed intent will intuition QTKit to raise an exception.

    The intent mechanism is also the artery that the novel features of QuickTime X are exposed, such as the competence to asynchronously load great or distantly located (e.g., over a slack network link) movie files without blocking the UI running on the main thread of the application.

    Indeed, there are many reasons to execute what it takes to Get on board the QuickTime X train. For the media formats it supports, QuickTime X is less taxing on the CPU during playback than QuickTime 7. (This is beyond the fact that QuickTime X does not squander time preparing its internal representation of the movie for editing and export when playback is entire that's desired.) QuickTime X also supports GPU-accelerated playback of H.264, but, in this initial release, only on Macs equipped with an NVIDIA 9400M GPU (i.e., some 2009 iMacs and several models of MacBooks from 2008 and 2009). Finally, QuickTime X includes comprehensive ColorSync champion for video, which is long overdue.

    The X factor

    This is just the start of a long journey for QuickTime X, and seemingly not a very auspicious one, at that. A QuickTime engine with no editing support? No plug-ins? It seems ridiculous to release it at all. But this has been Apple's artery in recent years: steady, deliberate progress. Apple aims to ship no features before their time.

    As anxious as developers may subsist for a full-featured, 64-bit successor to the QuickTime 7 engine, Apple itself is sitting on top of one of the largest QuickTime-riddled (and Carbon-addled, to boot) code bases in the industry: Final sever Studio. Thus far, It remains stuck in 32-bit. To snarl that Apple is "highly motivated" to extend the capabilities of QuickTime X would subsist an understatement.

    Nevertheless, don't expect Apple to rush forward foolishly. Duplicating the functionality of a continually developed, 18-year-old API will not betide overnight. It will purchase years, and it will subsist even longer before every distinguished Mac OS X application is updated to expend QTKit exclusively. Transitions. Gotta fancy 'em.

    File system API unification

    Mac OS X has historically supported many different ways of referring to files on disk from within an application. Plain-old paths (e.g., /Users/john/Documents/myfile) are supported at the lowest levels of the operating system. They're simple, predictable, but perhaps not such a powerful concept to expend as the only artery an application tracks files. regard what happens if an application opens a file based on a path string, then the user moves that file somewhere else while it's silent being edited. When the application is instructed to reclaim the file, if it only has the file path to work with, it will abide up creating a novel file in the veteran location, which is almost certainly not what the user wanted.

    Classic Mac OS had a more sophisticated internal representation of files that enabled it to track files independent of their actual locations on disk. This was done with the attend of the unique file ids supported by HFS/HFS+. The Mac OS X incarnation of this concept is the FSRef data type.

    Finally, in the modern age, URLs maintain become the de facto representation for files that may subsist located somewhere other than the local machine. URLs can also advert to local files, but in that case they maintain entire the selfsame disadvantages as file paths.

    This diversity of data types is reflected in Mac OS X's file system APIs. Some functions purchase file path as arguments, some expect opaque references to files, and silent others work only with URLs. Programs that expend these APIs often spend a lot of their time converting file references from one representation to another.

    The situation is similar when it comes to getting information about files. There are a huge number of file system metadata retrieval functions at entire levels of the operating system, and no sole one of them is comprehensive. To Get entire available information about a file on disk requires making several divorce calls, each of which may expect a different sort of file reference as an argument.

    Here's an case Apple provided at WWDC. Opening a sole file in the Leopard version of the Preview image viewer application results in:

  • Four conversions of an FSRef to a file path
  • Ten conversions of a file path to an FSRef
  • Twenty-five calls to getattrlist()
  • Eight calls to stat()/lstat()
  • Four calls to open()/close()
  • In Snow Leopard, Apple has created a new, unified, comprehensive set of file system APIs built around a sole data type: URLs. But these are URL "objects"—namely, the opaque data types NSURL and CFURL, with a toll-free bridge between them—that maintain been imbued with entire the desirable attributes of an FSRef.

    Apple settled on these data types because their opaque nature allowed this kind of enhancement, and because there are so many existing APIs that expend them. URLs are also the most future-proof of entire the choices, with the scheme portion providing nearly unlimited flexibility for novel data types and access mechanisms. The novel file system APIs built around these opaque URL types champion caching and metadata prefetching for a further performance boost.

    There's also a novel on-disk representation called a Bookmark (not to subsist confused with a browser bookmark) which is love a more network-savvy replacement for classic Mac OS aliases. Bookmarks are the most robust artery to create a reference to a file from within another file. It's also feasible to attach whimsical metadata to each Bookmark. For example, if an application wants to support a persistent list of "favorite" files plus some application-specific information about them, and it wants to subsist resilient to any movement of these files behind its back, Bookmarks are the best appliance for the job.

    I mention entire of this not because I expect file system APIs to subsist entire that thoughtprovoking to people without my particular fascination with this portion of the operating system, but because, love Core Text before it, it's an indication of exactly how youthful Mac OS X really is as a platform. Even after seven major releases, Mac OS X is silent struggling to fling out from the shadow of its three ancestors: NeXTSTEP, classic Mac OS, and BSD Unix. Or perhaps it just goes to reveal how ruthlessly Apple's core OS team is driven to replace veteran and crusty APIs and data types with new, more modern versions.

    It will subsist a long time before the benefits of these changes trickle down (or is it up?) to end-users in the form of Mac applications that are written or modified to expend these novel APIs. Most well-written Mac applications already exhibit most of the desirable behavior. For example, the TextEdit application in Leopard will correctly detect when a file it's working on has moved.

    TextEdit: a pleasurable Mac OS X citizenTextEdit: a pleasurable Mac OS X citizen

    Of course, the key modifier here is "well-written." Simplifying the file system APIs means that more developers will subsist willing to expend the effort—now greatly reduced—to provide such user-friendly behaviors. The accompanying performance boost is just icing on the cake, and one more intuition that developers might elect to alter their existing, working application to expend these novel APIs.

    Doing more with more

    Moore's Law is widely cited in technology circles—and also widely misunderstood. It's most often used as shorthand for "computers double in hasten every year or so," but that's not what Gordon Moore wrote at all. His 1965 article in Electronics magazine touched on many topics in the semiconductor industry, but if it had to subsist summed up in a sole "law", it would be, roughly, that the number of transistors that proper onto a square inch of silicon doubles every 12 months.

    Moore later revised that to two years, but the time age is not what people Get wrong. The problem is confusing a doubling of transistor density with a doubling of "computer speed." (Even more problematic is declaring a "law" based on a sole paper from 1965, but we'll outcome that aside for now. For a more thorough discussion of Moore's Law, gladden read this classic article by Jon Stokes.)

    For decades, each expand in transistor density was, in fact, accompanied by a comparable expand in computing hasten thanks to ever-rising clock speeds and the dawn of superscalar execution. This worked great—existing code ran faster on each novel CPU—until the grim realities of power density outcome an abide to the fun.

    Moore's Law continues, at least for now, but their competence to fabricate code Run faster with each novel expand in transistor density has slowed considerably. The free lunch is over. CPU clock speeds maintain stagnated for years, many times actually going backwards. (The latest top-of-the-line 2009 Mac Pro contains a 2.93 GHz CPU, whereas the 2008 model could subsist equipped with a 3.2 GHz CPU.) Adding execution units to a CPU has also long since reached the point of diminishing returns, given the limits of instruction-level parallelism in common application code.

    And yet we've silent got entire these novel transistors raining down on us, more every year. The challenge is to find novel ways to expend them to actually fabricate computers faster.

    Thus far, the semiconductor industry's respond has been to give us more of what they already have. Where once a CPU contained a sole logical processing unit, now CPUs in even the lowliest desktop computers hold two processor cores, with high-end models sporting two chips with eight logical cores each. Granted, the cores themselves are also getting faster, usually by doing more at the selfsame clock hasten as their predecessors, but that's not happening at nearly the rate that the cores are multiplying.

    Unfortunately, generally speaking, a dual-core CPU will not Run your application twice as hastily as a single-core CPU. In fact, your application probably won't Run any faster at entire unless it was written to purchase edge of more than just a sole logical CPU. Presented with a glut of transistors, chipmakers maintain turned around and provided more computing resources than programmers know what to execute with, transferring much of the responsibility for making computers faster to the software guys.

    We're with the operating system and we're here to help

    It's into this environment that Snow Leopard is born. If there's one responsibility (aside from security) that an operating system vendor should feel in the year 2009, it's finding a artery for applications—and the OS itself—to utilize the ever-growing wealth of computing resources at their disposal. If I had to pick sole technological "theme" for Snow Leopard, this would subsist it: helping developers utilize entire this newfound silicon; helping them execute more with more.

    To that end, Snow Leopard includes two significant novel APIs backed by several smaller, but equally distinguished infrastructure improvements. We'll start at the bottom with, believe it or not, the compiler.

    LLVM and Clang

    Apple made a strategic investment in the LLVM open source project several years ago. I covered the fundamentals of LLVM in my Leopard review. (If you're not up to speed, gladden enmesh up on the topic before continuing.) In it, I described how Leopard used LLVM to provide dramatically more efficient JIT-compiled software implementations of OpenGL functions. I ended with the following admonition:

    Don't subsist misled by its humble expend in Leopard; Apple has august plans for LLVM. How grand? How about swapping out the guts of the gcc compiler Mac OS X uses now and replacing them with the LLVM equivalents? That project is well underway. Not ambitious enough? How about ditching gcc entirely, replacing it with a completely novel LLVM-based (but gcc-compatible) compiler system? That project is called Clang, and it's already yielded some impressive performance results.

    With the introduction of Snow Leopard, it's official: Clang and LLVM are the Apple compiler strategy going forward. LLVM even has a snazzy novel logo, a not-so-subtle homage to a well-known compiler design textbook:

    LLVM! Clang! Rawr!

    LLVM! Clang! Rawr!

    Apple now offers a total of four compilers for Mac OS X: GCC 4.0, GCC 4.2, LLVM-GCC 4.2 (the GCC 4.2 front-end combined with an LLVM back-end), and Clang, in order of increasing LLVM-ness. Here's a diagram:

    Mac OS X compilers

    Mac OS X compilers

    All of these compilers are binary-compatible on Mac OS X, which means you can, for example, build a library with one compiler and link it into an executable built with another. They're also entire command-line and source-compatible—in theory, anyway. Clang does not yet champion some of the more esoteric features of GCC. Clang also only supports C, Objective-C, and a tiny bit of C++ (Clang(uage), Get it?) whereas GCC supports many more. Apple is committed to complete C++ champion for Clang, and hopes to work out the remaining GCC incompatibilities during Snow Leopard's lifetime.

    Clang brings with it the two headline attributes you expect in a hot, novel compiler: shorter compile times and faster executables. In Apple's testing with its own applications such as iCal, Address Book, and Xcode itself, plus third-party applications love Adium and Growl, Clang compiles nearly three times faster than GCC 4.2. As for the hasten of the finished product, the LLVM back-end, whether used in Clang or in LLVM-GCC, produces executables that are 5-25% faster than those generated by GCC 4.2.

    Clang is also more developer-friendly than its GCC predecessors. I concede that this topic doesn't maintain much to execute with taking edge of multiple CPU cores and so on, but it's positive to subsist the first thing that a developer actually notices when using Clang. Indulge me.

    For starters, Clang is embeddable, so Xcode can expend the selfsame compiler infrastructure for interactive features within the IDE (symbol look-up, code completion, etc.) as it uses to compile the final executable. Clang also creates and preserves more extensive metadata while compiling, resulting in much better mistake reporting. For example, when GCC tells you this:

    GCC mistake message for an unknown type

    It's not exactly limpid what the problem is, especially if you're novel to C programming. Yes, entire you hotshots already know what the problem is (especially if you saw this case at WWDC), but I speculate everyone can accord that this error, generated by Clang, is a lot more helpful:

    Clang mistake message for an unknown type

    Maybe a novice silent wouldn't know what to do, but at least it's limpid where the problem lies. Figuring out why the compiler doesn't know about NSString is a much more focused assignment than can subsist derived from GCC's cryptic error.

    Even when the message is clear, the context may not be. purchase this mistake from GCC:

    GCC mistake message for heinous operands

    Sure, but there are four "+" operators on that sole line. Which one has the problematic operands? Thanks to its more extensive metadata, Clang can pinpoint the problem:

    Clang mistake message for heinous operands

    Sometimes the mistake is perfectly clear, but it just seems a bit off, love this situation where jumping to the mistake as reported by GCC puts you on the line below where you actually want to add the missing semicolon:

    GCC mistake message for missing semicolon

    The tiny things count, you know? Clang goes that extra mile:

    Clang mistake message for missing semicolon

    Believe it or not, stuff love this means a lot to developers. And then there are the not-so-little things that connote even more, love the LLVM-powered static analyzer. The image below shows how the static analyzer displays its discovery of a feasible bug.

    OH HAI I institute UR BUGOH HAI I institute UR BUG

    Aside from the whimsy of the tiny arrows (which, admit it, are adorable), the actual bug it's highlighting is something that every programmer can imagine creating (say, through some hasty editing). The static analyzer has determined that there's at least one path through this set of nested conditionals that leaves the myName variable uninitialized, thus making the attempt to forward the mutableCopy message in the final line potentially dangerous.

    I'm positive Apple is going hog-wild running the static analyzer on entire of its applications and the operating system itself. The prospect of an automated artery to learn bugs that may maintain existed for years in the depths of a huge codebase is almost pornographic to developers—platform owners in particular. To the degree that Mac OS X 10.6.0 is more bug-free than the previous 10.x.0 releases, LLVM surely deserves some significant portion of the credit.

    Master of the house

    By committing to a Clang/LLVM-powered future, Apple has finally taken complete control of its evolution platform. The CodeWarrior undergo apparently convinced Apple that it's unwise to rely on a third party for its platform's evolution tools. Though it's taken many years, I speculate even the most diehard Metrowerks fan would maintain to accord that Xcode in Snow Leopard is now a pretty damn pleasurable IDE.

    After years of struggling with the disconnect between the goals of the GCC project and its own compiler needs, Apple has finally sever the apron strings. OK, granted, GCC 4.2 is silent the default compiler in Snow Leopard, but this is a transitional phase. Clang is the recommended compiler, and the focus of entire of Apple's future efforts.

    I know what you're thinking. This is swell and all, but how are these compilers helping developers better leverage the expanding swarm of transistors at their disposal? As you'll see in the following sections, LLVM's scaly, metallic head pops up in a few key places.


    In Snow Leopard, Apple has introduced a C language extension called "blocks." Blocks add closures and anonymous functions to C and the C-derived languages C++, Objective-C, and Objective C++.

    These features maintain been available in dynamic programming languages such as Lisp, Smalltalk, Perl, Python, Ruby, and even the unassuming JavaScript for a long time (decades, in the case of Lisp—a fact gladly offered by its practitioners). While dynamic-language programmers purchase closures and anonymous functions for granted, those who work with more traditional, statically compiled languages such as C and its derivatives may find them quite exotic. As for non-programmers, they likely maintain no interest in this topic at all. But I'm going to attempt an explanation nonetheless, as blocks form the foundation of some other thoughtprovoking technologies to subsist discussed later.

    Perhaps the simplest artery to justify blocks is that they fabricate functions another form of data. C-derived languages already maintain duty pointers, which can subsist passed around love data, but these can only point to functions created at compile time. The only artery to influence the behavior of such a duty is by passing different arguments to the duty or by setting global variables which are then accessed from within the function. Both of these approaches maintain astronomical disadvantages

    Passing arguments becomes cumbersome as their number and complexity grows. Also, it may subsist that you maintain limited control over the arguments that will subsist passed to your function, as is often the case with callbacks. To compensate, you may maintain to bundle up entire of your thoughtprovoking situation into a context kick of some kind. But when, how, and by whom that context data will subsist disposed of can subsist difficult to pin down. Often, a second callback is required for this. It's entire quite a pain.

    As for the expend of global variables, in addition to being a well-known anti-pattern, it's also not thread-safe. To fabricate it so requires locks or some other form of mutual exclusion to preclude multiple invocations of the selfsame duty from stepping on each other's toes. And if there's anything worse than navigating a sea of callback-based APIs, it's manually dealing with thread safety issues.

    Blocks bypass entire of these problems by allowing functional blobs of code—blocks—to subsist defined at runtime. It's easiest to understand with an example. I'm going to start by using JavaScript, which has a bit friendlier syntax, but the concepts are the same.

    b = get_number_from_user(); multiplier = function(a) { revert a * b };

    Here I've created a duty named multiplier that takes a sole argument, a, and multiplies it by a second value, b, that's provided by the user at runtime. If the user supplied the number 2, then a summon to multiplier(5) would revert the value 10.

    b = get_number_from_user(); // assume it's 2 multiplier = function(a) { revert a * b }; r = multiplier(5); // 5 * 2 = 10

    Here's the case above done with blocks in C.

    b = get_number_from_user(); // assume it's 2 multiplier = ^ int (int a) { revert a * b; }; r = multiplier(5); // 5 * 2 = 10

    By comparing the JavaScript code to the C version, I hope you can see how it works. In the C example, that tiny caret ^ is the key to the syntax for blocks. It's kind of ugly, but it's very C-like in that it parallels the existing C syntax for duty pointers, with ^ in location of *, as this case illustrates:

    /* A duty that takes a sole integer controversy and returns a pointer to a duty that takes two integer arguments and returns a floating-point number. */ float (*func2(int a))(int, int); /* A duty that takes a sole integer controversy and returns a obstruct that takes two integer arguments and returns a floating-point number. */ float (^func1(int a))(int, int);

    You'll just maintain to trust me when I explicate you that this syntax actually makes sense to seasoned C programmers.

    Now then, does this connote that C is suddenly a dynamic, high-level language love JavaScript or Lisp? Hardly. The existing distinction between the stack and the heap, the rules governing automatic and static variables, and so on are entire silent in complete effect. Plus, now there's a entire novel set of rules for how blocks interact with each of these things. There's even a novel __block storage sort impute to further control the scope and lifetime of values used in blocks.

    All of that said, blocks are silent a huge win in C. Thanks to blocks, the friendlier APIs long enjoyed by dynamic languages are now feasible in C-derived languages. For example, suppose you want to apply some operation to every line in a file. To execute so in a low-level language love C requires some amount of boilerplate code to open and read from the file, wield any errors, read each line into a buffer, and antiseptic up at the end.

    FILE *fp = fopen(filename, "r"); if (fp == NULL) { perror("Unable to open file"); } else { char line[MAX_LINE]; while (fgets(line, MAX_LINE, fp)) { work; work; work; } fclose(fp); }

    The portion in bold is an abstract representation of what you're planning to execute to each line of the file. The rest is the literal boilerplate code. If you find yourself having to apply varying operations to every line of many different files, this boilerplate code gets tedious.

    What you'd love to subsist able to execute is factor it out into a duty that you can call. But then you're faced with the problem of how to express the operation you'd love to discharge on each line of the file. In the middle of each obstruct of boilerplate may subsist many lines of code expressing the operation to subsist applied. This code may reference or modify local variables which are affected by the runtime behavior of the program, so traditional duty pointers won't work. What to do?

    Thanks to blocks, you can define a duty that takes a filename and a obstruct as arguments. This gets entire the uninteresting code out of your face.

    foreach_line(filename, ^ (char *line) { work; work; work; });

    What's left is a much clearer expression of your intent, with less surrounding noise. The controversy after filename is a literal obstruct that takes a line of text as an argument.

    Even when the volume of boilerplate is small, the simplicity and clarity prize is silent worthwhile. regard the simplest feasible loop that executes a fixed number of times. In C-based languages, even that basic construct offers a surprising number of opportunities for bugs. Let's do_something() 10 times:

    for (int i = 0; i <= 10; i++) { do_something(); }

    Oops, I've got a tiny bug there, don't I? It happens to the best of us. But why should this code subsist more complicated than the sentence describing it. execute something 10 times! I never want to screw that up again. Blocks can help. If they just invest a tiny trouble up front to define a helper function:

    typedef void (^work_t)(void); void repeat(int n, work_t block) { for (int i = 0; i < n; ++i) block(); }

    We can exile the bug for good. Now, repeating any whimsical obstruct of code a specific number of times is entire but idiot-proof:

    repeat(10, ^{ do_something() }); repeat(20, ^{ do_other_thing() });

    And remember, the obstruct controversy to repeat() can hold exactly the selfsame kind of code, literally copied and pasted, that would maintain appeared within a traditional for loop.

    All these possibilities and more maintain been well explored by dynamic languages: map, reduce, collect, etc. Welcome, C programmers, to a higher order.

    Apple has taken these lessons to heart, adding over 100 novel APIs that expend blocks in Snow Leopard. Many of these APIs would not subsist feasible at entire without blocks, and entire of them are more elegant and concise than they would subsist otherwise.

    It's Apple objective to submit blocks as an official extension to one or more of the C-based languages, though it's not yet limpid which standards bodies are receptive to the proposal. For now, blocks are supported by entire four of Apple's compilers in Mac OS X.

    Concurrency in the existent world: a prelude

    The struggle to fabricate efficient expend of a great number of independent computing devices is not new. For decades, the realm of high-performance computing has tackled this problem. The challenges faced by people writing software for supercomputers many years ago maintain now trickled down to desktop and even mobile computing platforms.

    In the PC industry, some people saw this coming earlier than others. Almost 20 years ago, subsist Inc. was formed around the concept of creating a PC platform unconstrained by legacy limitations and entirely prepared for the coming abundance of independent computing units on the desktop. To that end, subsist created the BeBox, a dual-CPU desktop computer, and BeOS, a brand-new operating system.

    The signature enmesh phrase for BeOS was "pervasive multithreading." The BeBox and other machines running BeOS leveraged every ounce of the diminutive (by today's standards, anyway) computing resources at their disposal. The demos were impressive. A dual 66 MHz machine (don't fabricate me reveal another graph) could play multiple videos simultaneously while also playing several audio tracks from a CD—some backwards— and entire the while, the user interface remained completely responsive.

    Let me explicate you, having lived through this age myself, the undergo was mind-blowing at the time. BeOS created instant converts out of hundreds of technology enthusiasts, many of whom maintain that today's desktop computing undergo silent doesn't match the responsiveness of BeOS. This is certainly suitable emotionally, if not necessarily literally.

    After nearly purchasing subsist in the late 1990s, Apple bought NeXT instead, and the rest is history. But had Apple gone with blueprint subsist instead, Mac developers might maintain had a harsh road ahead. While entire that pervasive multithreading made for impressive technology demos and a powerful user experience, it could subsist extremely demanding on the programmer. BeOS was entire about threads, going so far as to maintain a divorce thread for each window. Whether you liked it or not, your BeOS program was going to subsist multithreaded.

    Parallel programming is notoriously hard, with the manual management of POSIX-style threads representing the abysmal abide of that pool. The best programmers in the world are hard-pressed to create great multithreaded programs in low-level languages love C or C++ without finding themselves impaled on the spikes of deadlock, race conditions, and other perils inherent in the expend of in multiple simultaneous threads of execution that share the selfsame reminiscence space. Extremely heedful application of locking primitives is required to avoid performance-robbing levels of contention for shared data—and the bugs, oh the bugs! The term "Heisenbug" may as well maintain been invented for multithreaded programming.

    Nineteen years after subsist tilted at the windmill of the widening swath of silicon in desktop PCs, the challenge has only grown. Those transistors are out there, man—more than ever before. Single-threaded programs on today's high-end desktop Macs, even when using "100%" CPU, extend but a sole glowing tower in a sea of sixteen otherwise blank lanes on a CPU monitor window.

    A wide-open plain of transistorsA wide-open plain of transistors

    And woe subsist unto the user if that pegged CPU core is running the main thread of a GUI application on Mac OS X. A CPU-saturated main thread means no novel user inputs are being pulled off the event queue by the application. A few seconds of that and an veteran friend makes its appearance: the spinning beach ball of death.


    Nooooooooo!!! Image from The Iconfactory

    This is the enemy: hardware with more computing resources than programmers know what to execute with, most of it completely idle, and entire the while the user is utterly blocked in his attempts to expend the current application. What's Snow Leopard's answer? Read on…

    Grand Central Dispatch Apple's GCD branding: <a href="">Railfan</a> <a href="">service</a>Apple's GCD branding: Railfan service

    Snow Leopard's respond to the concurrency conundrum is called august Central Dispatch (GCD). As with QuickTime X, the name is extremely apt, though this is not entirely limpid until you understand the technology.

    The first thing to know about GCD is that it's not a novel Cocoa framework or similar special-purpose frill off to the side. It's a plain C library baked into the lowest levels of Mac OS X. (It's in libSystem, which incorporates libc and the other code that sits at the very bottom of userspace.)

    There's no requisite to link in a novel library to expend GCD in your program. Just #include <dispatch/dispatch.h> and you're off to the races. The fact that GCD is a C library means that it can subsist used from entire of the C-derived languages supported on Mac OS X: Objective-C, C++, and Objective-C++.

    Queues and threads

    GCD is built on a few simple entities. Let's start with queues. A queue in GCD is just what it sounds like. Tasks are enqueued, and then dequeued in FIFO order. (That's "First In, First Out," just love the checkout line at the supermarket, for those who don't know and don't want to ensue the link.) Dequeuing the assignment means handing it off to a thread where it will execute and execute its actual work.

    Though GCD queues will hand tasks off to threads in FIFO order, several tasks from the selfsame queue may subsist running in parallel at any given time. This animation demonstrates.

    A august Central Dispatch queue in action

    You'll notice that assignment B completed before assignment A. Though dequeuing is FIFO, assignment completion is not. also note that even though there were three tasks enqueued, only two threads were used. This is an distinguished feature of GCD which we'll discuss shortly.

    But first, let's survey at the other kind of queue. A serial queue works just love a traditional queue, except that it only executes one assignment at a time. That means assignment completion in a serial queue is also FIFO. Serial queues can subsist created explicitly, just love traditional queues, but each application also has an implicit "main queue" which is a serial queue that runs on the main thread.

    The animation above shows threads appearing as work needs to subsist done, and disappearing as they're no longer needed. Where execute these threads arrive from and where execute they Go when they're done? GCD maintains a global pool of threads which it hands out to queues as they're needed. When a queue has no more pending tasks to Run on a thread, the thread goes back into the pool.

    This is an extremely distinguished aspect of GCD's design. Perhaps surprisingly, one of the most difficult parts of extracting maximum performance using traditional, manually managed threads is figuring out exactly how many threads to create. Too few, and you risk leaving hardware idle. Too many, and you start to spend a significant amount of time simply shuffling threads in and out of the available processor cores.

    Let's snarl a program has a problem that can subsist split into eight separate, independent units of work. If this program then creates four threads on an eight-core machine, is this an case of creating too many or too few threads? Trick question! The respond is that it depends on what else is happening on the system.

    If six of the eight cores are totally saturated doing some other work, then creating four threads will just require the OS to squander time rotating those four threads through the two available cores. But wait, what if the process that was saturating those six cores finishes? Now there are eight available cores but only four threads, leaving half the cores idle.

    With the exception of programs that can reasonably expect to maintain the entire machine to themselves when they run, there's no artery for a programmer to know ahead of time exactly how many threads he should create. Of the available cores on a particular machine, how many are in use? If more become available, how will my program know?

    The bottom line is that the optimal number of threads to outcome in flight at any given time is best determined by a single, globally watchful entity. In Snow Leopard, that entity is GCD. It will support zero threads in its pool if there are no queues that maintain tasks to run. As tasks are dequeued, GCD will create and dole out threads in a artery that optimizes the expend of the available hardware. GCD knows how many cores the system has, and it knows how many threads are currently executing tasks. When a queue no longer needs a thread, it's returned to the pool where GCD can hand it out to another queue that has a assignment ready to subsist dequeued.

    There are further optimizations inherent in this scheme. In Mac OS X, threads are relatively heavyweight. Each thread maintains its own set of register values, stack pointer, and program counter, plus kernel data structures tracking its security credentials, scheduling priority, set of pending signals and signal masks, etc. It entire adds up to over 512 KB of overhead per thread. Create a thousand threads and you've just burned about a half a gigabyte of reminiscence and kernel resources on overhead alone, before even considering the actual data within each thread.

    Compare a thread's 512 KB of baggage with GCD queues which maintain a mere 256 bytes of overhead. Queues are very lightweight, and developers are encouraged to create as many of them as they need—thousands, even. In the earlier animation, when the queue was given two threads to process its three tasks, it executed two tasks on one of the threads. Not only are threads heavyweight in terms of reminiscence overhead, they're also relatively costly to create. Creating a novel thread for each assignment would subsist the worst feasible scenario. Every time GCD can expend a thread to execute more than one task, it's a win for overall system efficiency.

    Remember the problem of the programmer trying to device out how many threads to create? Using GCD, he doesn't maintain to worry about that at all. Instead, he can concentrate entirely on the optimal concurrency of his algorithm in the abstract. If the best-case scenario for his problem would expend 500 concurrent tasks, then he can Go ahead and create 500 GCD queues and ration his work among them. GCD will device out how many actual threads to create to execute the work. Furthermore it will adjust the number of threads dynamically as the conditions on the system change.

    But perhaps most importantly, as novel hardware is released with more and more CPU cores, the programmer does not requisite to change his application at all. Thanks to GCD, it will transparently purchase edge of any and entire available computing resources, up to—but not past!—the optimal amount of concurrency as originally defined by the programmer when he chose how many queues to create.

    But wait, there's more! GCD queues can actually subsist arranged in arbitrarily complex directed acyclic graphs. (Actually, they can subsist cyclic too, but then the behavior is undefined. Don't execute that.) Queue hierarchies can subsist used to funnel tasks from disparate subsystems into a narrower set of centrally controlled queues, or to compel a set of traditional queues to delegate to a serial queue, effectively serializing them entire indirectly.

    There are also several levels of priority for queues, dictating how often and with what urgency threads are distributed to them from the pool. Queues can subsist suspended, resumed, and cancelled. Queues can also subsist grouped, allowing entire tasks distributed to the group to subsist tracked and accounted for as a unit.

    Overall, GCD's expend of queues and threads forms a simple, elegant, but also extremely pragmatic architecture.


    Okay, so GCD is a powerful artery to fabricate efficient expend of the available hardware. But is it really any better than BeOS's approach to multithreading? We've already seen a few ways that GCD avoids the pitfalls of BeOS (e.g., the reuse of threads and the maintenance of a global pool of threads that's correctly sized for the available hardware). But what about the problem of overwhelming the programmer by requiring threads in places where they complicate, rather than enhance the application?

    GCD embodies a philosophy that is at the antithetical abide of the spectrum from BeOS's "pervasive multithreading" design. Rather than achieving responsiveness by getting every feasible component of an application running concurrently on its own thread (and paying a hefty price in terms of complex data sharing and locking concerns), GCD encourages a much more limited, hierarchical approach: a main application thread where entire the user events are processed and the interface is updated, and worker threads doing specific jobs as needed.

    In other words, GCD doesn't require developers to speculate about how best to split the work of their application into multiple concurrent threads (though when they're ready to execute that, GCD will subsist willing and able to help). At its most basic level, GCD aims to encourage developers to fling from thinking synchronously to thinking asynchronous. Something love this: "Write your application as usual, but if there's any portion of its operation that can reasonably subsist expected to purchase more than a few seconds to complete, then for the fancy of Zarzycki, Get it off the main thread!"

    That's it; no more, no less. Beach ball banishment is the cornerstone of user interface responsiveness. In some respects, everything else is gravy. But most developers know this intuitively, so why execute they silent see the beach ball in Mac OS X applications? Why don't entire applications already execute entire of their potentially long-running tasks on background threads?

    A few reasons maintain been mentioned already (e.g., the difficulty of knowing how many threads to create) but the astronomical one is much more pragmatic. Spinning off a thread and collecting its result has always been a bit of a pain. It's not so much that it's technically difficult, it's just that it's such an categorical atomize from coding the actual work of your application to coding entire this task-management plumbing. And so, especially in borderline cases, love an operation that may purchase 3 to 5 seconds, developers just execute it synchronously and fling onto the next thing.

    Unfortunately, there's a surprising number of very common things that an application can execute that execute quickly most of the time, but maintain the potential to purchase much longer than a few seconds when something goes wrong. Anything that touches the file system may stall at the lowest levels of the OS (e.g., within blocking read() and write() calls) and subsist theme to a very long (or at least an "unexamined-by-the-application-developer") timeout. The selfsame goes for name lookups (e.g., DNS or LDAP), which almost always execute instantly, but enmesh many applications completely off-guard when they start taking their sweet time to revert a result. Thus, even the most meticulously constructed Mac OS X applications can abide up throwing the beach ball in their kisser from time to time.

    With GCD, Apple is aphorism it doesn't maintain to subsist this way. For example, suppose a document-based application has a button that, when clicked, will dissect the current document and display some thoughtprovoking statistics about it. In the common case, this analysis should execute in under a second, so the following code is used to connect the button with an action:

    - (IBAction)analyzeDocument:(NSButton *)sender { NSDictionary *stats = [myDoc analyze]; [myModel setDict:stats]; [myStatsView setNeedsDisplay:YES]; [stats release]; }

    The first line of the duty body analyzes the document, the second line updates the application's internal state, and the third line tells the application that the statistics view needs to subsist updated to reflect this novel state. It entire follows a very common pattern, and it works powerful as long as notanyone of these steps—which are entire running on the main thread, remember—takes too long. Because after the user presses the button, the main thread of the application needs to wield that user input as hastily as feasible so it can Get back to the main event loop to process the next user action.

    The code above works powerful until a user opens a very great or very complex document. Suddenly, the "analyze" step doesn't purchase one or two seconds, but 15 or 30 seconds instead. Hello, beach ball. And still, the developer is likely to hem and haw: "This is really an exceptional situation. Most of my users will never open such a great file. And anyway, I really don't want to start reading documentation about threads and adding entire that extra code to this simple, four-line function. The plumbing would dwarf the code that does the actual work!"

    Well, what if I told you that you could fling the document analysis to the background by adding just two lines of code (okay, and two lines of closing braces), entire located within the existing function? No application-global objects, no thread management, no callbacks, no controversy marshalling, no context objects, not even any additional variables. Behold, august Central Dispatch:

    - (IBAction)analyzeDocument:(NSButton *)sender { dispatch_async(dispatch_get_global_queue(0, 0), ^{ NSDictionary *stats = [myDoc analyze]; dispatch_async(dispatch_get_main_queue(), ^{ [myModel setDict:stats]; [myStatsView setNeedsDisplay:YES]; [stats release]; }); }); }

    There's a hell of a lot of packed into those two lines of code. entire of the functions in GCD originate with dispatch_, and you can see four such calls in the blue lines of code above. The key to the minimal invasiveness of this code is revealed in the second controversy to the two dispatch_async() calls. Thus far, I've been discussing "units of work" without specifying how, exactly, GCD models such a thing. The answer, now revealed, should appear obvious in retrospect: blocks! The competence of blocks to capture the surrounding context is what allows these GCD calls to subsist dropped privilege into some existing code without requiring any additional setup or re-factoring or other contortions in service of the API.

    But the best portion of this code is how it deals with the problem of detecting when the background assignment completes and then showing the result. In the synchronous code, the dissect manner summon and the code to update the application display simply issue in the desired sequence within the function. In the asynchronous code, miraculously, this is silent the case. Here's how it works.

    The outer dispatch_async() summon puts a assignment on a global concurrent GCD queue. That task, represented by the obstruct passed as the second argument, contains the potentially time-consuming dissect manner call, plus another summon to dispatch_async() that puts a assignment onto the main queue—a serial queue that runs on the main thread, remember—to update the application's user interface.

    User interface updates must entire subsist done from the main thread in a Cocoa application, so the code in the inner obstruct could not subsist executed anywhere else. But rather than having the background thread forward some kind of special-purpose notification back to the main thread when the dissect manner summon completes (and then adding some code to the application to detect and wield this notification), the work that needs to subsist done on the main thread to update the display is encapsulated in yet another obstruct within the larger one. When the dissect summon is done, the inner obstruct is outcome onto the main queue where it will (eventually) Run on the main thread and execute its work of updating the display.

    Simple, elegant, and effective. And for developers, no more excuses.

    Believe it or not, it's just as simple to purchase a serial implementation of a chain of independent operations and parallelize it. The code below does work on count elements of data, one after the other, and then summarizes the results once entire the elements maintain been processed.

    for (i = 0; i < count; i++) { results[i] = do_work(data, i); } total = summarize(results, count);

    Now here's the parallel version which puts a divorce assignment for each component onto a global concurrent queue. (Again, it's up to GCD to resolve how many threads to actually expend to execute the tasks.)

    dispatch_apply(count, dispatch_get_global_queue(0, 0), ^(size_t i) { results[i] = do_work(data, i); }); total = summarize(results, count);

    And there you maintain it: a for loop replaced with a concurrency-enabled equivalent with one line of code. No preparation, no additional variables, no impossible decisions about the optimal number of threads, no extra work required to wait for entire the independent tests to complete. (The dispatch_apply() summon will not revert until entire the tasks it has dispatched maintain completed.) Stunning.

    Grand Central Awesome

    Of entire the APIs added in Snow Leopard, august Central Dispatch has the most far-reaching implications for the future of Mac OS X. Never before has it been so simple to execute work asynchronously and to spread workloads across many CPUs.

    When I first heard about august Central Dispatch, I was extremely skeptical. The greatest minds in computer science maintain been working for decades on the problem of how best to extract parallelism from computing workloads. Now here was Apple apparently promising to unravel this problem. Ridiculous.

    But august Central Dispatch doesn't actually address this issue at all. It offers no attend whatsoever in deciding how to split your work up into independently executable tasks—that is, deciding what pieces can or should subsist executed asynchronously or in parallel. That's silent entirely up to the developer (and silent a tough problem). What GCD does instead is much more pragmatic. Once a developer has identified something that can subsist split off into a divorce task, GCD makes it as simple and non-invasive as feasible to actually execute so.

    The expend of FIFO queues, and especially the existence of serialized queues, seems counter to the spirit of ubiquitous concurrency. But we've seen where the Platonic exemplar of multithreading leads, and it's not a pleasant location for developers.

    One of Apple's slogans for august Central Dispatch is "islands of serialization in a sea of concurrency." That does a powerful job of capturing the practical reality of adding more concurrency to run-of-the-mill desktop applications. Those islands are what insulate developers from the thorny problems of simultaneous data access, deadlock, and other pitfalls of multithreading. Developers are encouraged to identify functions of their applications that would subsist better executed off the main thread, even if they're made up of several sequential or otherwise partially interdependent tasks. GCD makes it simple to atomize off the entire unit of work while maintaining the existing order and dependencies between subtasks.

    Those with some multithreaded programming undergo may subsist unimpressed with the GCD. So Apple made a thread pool. astronomical deal. They've been around forever. But the angels are in the details. Yes, the implementation of queues and threads has an elegant simplicity, and baking it into the lowest levels of the OS really helps to lower the perceived barrier to entry, but it's the API built around blocks that makes august Central Dispatch so attractive to developers. Just as Time Machine was "the first backup system people will actually use," august Central Dispatch is poised to finally spread the heretofore dim expertise of asynchronous application design to entire Mac OS X developers. I can't wait.

    OpenCL Somehow, OpenCL got in on the <a href="">"core" branding</a>Somehow, OpenCL got in on the "core" branding

    So far, we've seen a few examples of doing more with more: a new, more modern compiler infrastructure that supports an distinguished novel language feature, and a powerful, pragmatic concurrency API built on top of the novel compilers' champion for said language feature. entire this goes a long artery towards helping developers and the OS itself fabricate maximum expend of the available hardware.

    But CPUs are not the only components experiencing a glut of transistors. When it comes to the proliferation of independent computation engines, another piece of silicon inside every Mac is the undisputed title holder: the GPU.

    The numbers explicate the tale. While Mac CPUs hold up to four cores (which may reveal up as eight logical cores thanks to symmetric multithreading), high-end GPUs hold well over 200 processor cores. While CPUs are just now edging over 100 GFLOPS, the best GPUs are capable of over 1,000 GFLOPS. That's one trillion floating-point operations per second. And love CPUs, GPUs now arrive more than one on a board.

    Writing for the GPU

    Unfortunately, the cores on a GPU are not general-purpose processors (at least not yet). They're much simpler computing engines that maintain evolved from the fixed-function silicon of their ancestors that could not subsist programmed directly at all. They don't champion the wealthy set of instructions available on CPUs, the maximum size of the programs that will Run is often limited and very small, and not entire of the features of the industry-standard IEEE floating-point computation specification are supported.

    Today's GPUs can subsist programmed, but the most common forms of programmability are silent firmly planted in the world of graphics programming: vertex shaders, geometry shaders, pixel shaders. Most of the languages used to program GPUs are similarly graphically focused: HLSL, GLSL, Cg.

    Nevertheless, there are computational tasks outside the realm of graphics that are a pleasurable proper for GPU hardware. It would subsist nice if there were a non-graphics-oriented language to write them in. Creating such a thing is quite a challenge, however. GPU hardware varies wildly in every imaginable way: number and sort of execution units, available data formats, instruction sets, reminiscence architecture, you name it. Programmers don't want to subsist exposed to these differences, but it's difficult to work around the complete lack of a feature or the unavailability of a particular data type.

    GPU vendor NVIDIA gave it a shot, however, and produced CUDA: a subset of the C language with extensions for vector data types, data storage specifiers that reflect typical GPU reminiscence hierarchy, and several bundled computational libraries. CUDA is but one entrant in the burgeoning GPGPU realm (General-Purpose computing on Graphics Processing Units). But coming from a GPU vendor, it faces an uphill battle with developers who really want a vendor-agnostic solution.

    In the world of 3D programming, OpenGL fills that role. As you've surely guessed by now, OpenCL aims to execute the selfsame for general-purpose computation. In fact, OpenCL is supported by the selfsame consortium as OpenGL: the ominously named Khronos Group. But fabricate no mistake, OpenCL is Apple's baby.

    Apple understood that OpenCL's best desultory of success was to become an industry standard, not just an Apple technology. To fabricate that happen, Apple needed the cooperation of the top GPU vendors, plus an agreement with an established, widely-recognized standards body. It took a while, but now it's entire arrive together.

    OpenCL is a lot love CUDA. It uses a C-like language with the vector extensions, it has a similar model of reminiscence hierarchy, and so on. This is no surprise, considering how closely Apple worked with NVIDIA during the evolution of OpenCL. There's also no artery any of the astronomical GPU vendors would radically alter their hardware to champion an as-yet-unproven standard, so OpenCL had to work well with GPUs already designed to champion CUDA, GLSL, and other existing GPU programming languages.

    The OpenCL difference

    This is entire well and good, but to maintain any impact on the day-to-day life of Mac users, developers actually maintain to expend OpenCL in their applications. Historically, GPGPU programming languages maintain not seen much expend in traditional desktop applications. There are several reasons for this.

    Early on, writing programs for the GPU often required the expend of vendor-specific assembly languages that were far removed from the undergo of writing a typical desktop application using a contemporary GUI API. The more C-like languages that came later remained either graphics-focused, vendor-specific, or both. Unless running code on the GPU would accelerate a core component of an application by an order of magnitude, most developers silent could not subsist bothered to navigate this alien world.

    And even if the GPU did give a huge hasten boost, relying on graphics hardware for general-purpose computation was very likely to narrow the potential audience for an application. Many older GPUs, especially those institute in laptops, cannot Run languages love CUDA at all.

    Apple's key decision in the design of OpenCL was to allow OpenCL programs to Run not just on GPUs, but on CPUs as well. An OpenCL program can query the hardware it's running on and enumerate entire eligible OpenCL devices, categorized as CPUs, GPUs, or dedicated OpenCL accelerators (the IBM Cell Blade server—yes, that Cell—is apparently one such device). The program can then dispatch its OpenCL tasks to any available device. It's also feasible to create a sole logical device consisting of any combination of eligible computing resources: two GPUs, a GPU and two CPUs, etc.

    The advantages of being able to Run OpenCL programs on both CPUs and GPUs are obvious. Every Mac running Snow Leopard, not just those with the recent-model GPUs, can Run a program that contains OpenCL code. But there's more to it than that.

    Certain kinds of algorithms actually Run faster on high-end multi-core CPUs than on even the very fastest available GPUs. At WWDC 2009, an engineer from Electronic Arts demonstrated an OpenCL port of a skinning engine from one of its games running over four times faster on a four-core Mac Pro than on an NVIDIA GeForce GTX285. Restructuring the algorithm and making many other changes to better suit the limitations (and strengths) of the GPU pushed it back ahead of the CPU by a wide margin, but sometimes you just want the system you maintain to Run well as-is. Being able to target the CPU is extremely useful in those cases.

    Moreover, writing vector code for Intel CPUs "the old-fashioned way" can subsist a existent pain. There's MMX, SSE, SSE2, SSE3, and SSE4 to deal with, entire with slightly different capabilities, and entire of which compel the programmer to write code love this:

    r1 = _mm_mul_ps(m1, _mm_add_ps(x1, x2));

    OpenCL's native champion for vector types de-clutters the code considerably:

    r1 = m1 * (x1 + x2);

    Similarly, OpenCL's champion for implicit parallelism makes it much easier to purchase edge of multiple CPU cores. Rather than writing entire the logic to split your data into pieces and ration those pieces to the parallel-computing hardware, OpenCL lets you write just the code to operate on a sole piece of the data and then forward it, along with the entire obstruct of data and the desired level of parallelism, to the computing device.

    This arrangement is taken for granted in traditional graphics programming, where code implicitly works on entire pixels in a texture or entire vertices in a polygon; the programmer only needs to write code that will exist in the "inner loop," so to speak. An API with champion for this kind of parallelism that runs on CPUs as well as GPUs fills an distinguished gap.

    Writing to OpenCL also future-proofs task- or data-parallel code. Just as the selfsame OpenGL code will Get faster and faster as newer, more powerful GPUs are released, so too will OpenCL code discharge better as CPUs and GPUs Get faster. The extra layer of abstraction that OpenCL provides makes this possible. For example, though vector code written several years ago using MMX got faster as CPU clock speeds increased, a more significant performance boost likely requires porting the code to one of the newer SSE instruction sets.

    As newer, more powerful vector instruction sets and parallel hardware becomes available, Apple will update its OpenCL implementations to purchase edge of them, just as video card makers and OS vendors update their OpenGL drivers to purchase edge of faster GPUs. Meanwhile, the application developer's code remains unchanged. Not even a recompile is required.

    Here subsist dragons (and trains)

    How, you may wonder, can the selfsame compiled code abide up executing using SSE2 on one machine and SSE4 on another, or on an NVIDIA GPU on one machine and an ATI GPU on another? To execute so would require translating the device-independent OpenCL code to the instruction set of the target computing device at runtime. When running on a GPU, OpenCL must also ship the data and the newly translated code over to the video card and collect the results at the end. When running on the CPU, OpenCL must arrange for the requested level of parallelism by creating and distributing threads appropriately to the available cores.

    Well, wouldn't you know it? Apple just happens to maintain two technologies that unravel these exact problems.

    Want to compile code "just in time" and ship it off to a computing device? That's what LLVM was born to do—and, indeed, what Apple did with it in Leopard, albeit on a more limited scale. OpenCL is a natural extension of that work. LLVM allows Apple to write a sole code generator for each target instruction set, and concentrate entire of its trouble on a sole device-independent code optimizer. There's no longer any requisite to duplicate these tasks, using one compiler to create the static application executable and having to jury-rig another for just-in-time compilation.

    (Oh, and by the way, recollect Core Image? That's another API that needs to compile code just-in-time and ship it off to execute on parallel hardware love GPUs and multi-core CPUs. In Snow Leopard, Core Image has been re-implemented using OpenCL, producing a hefty 25% overall performance boost.)

    To wield assignment parallelism and provision threads, OpenCL is built on top of august Central Dispatch. This is such a natural proper that it's a bit surprising that the OpenCL API doesn't expend blocks. I speculate Apple decided that it shouldn't press its luck when it comes to getting its home-grown technologies adopted by other vendors. This decision already seems to subsist paying off, as AMD has its own OpenCL implementation under way.

    The top of the pyramid

    Though the underlying technologies, Clang, blocks and august Central Dispatch, will undoubtedly subsist more widely used by developers, OpenCL represents the culmination of that particular technological thread in Snow Leopard. This is the gold benchmark of software engineering: creating a novel public API by structure it on top of lower-level, but equally well-designed and implemented public APIs.

    A unified abstraction for the ever-growing heterogeneous collection of parallel computing silicon in desktop computers was sorely needed. We've got an increasing population of powerful CPU cores, but they silent exist in numbers that are orders of magnitude lower than the hundreds of processing units in modern GPUs. On the other hand, GPUs silent maintain a ways to Go to enmesh up with the power and flexibility of a full-fledged CPU core. But even with entire the differences, writing code exclusively for either one of those worlds silent smacks of leaving money on the table.

    With OpenCL in hand, there's no longer a requisite to outcome entire your eggs in one silicon basket. And with the advent of hybrid CPU/GPU efforts love Intel's Larabee, which expend CPU-caliber processing engines, but in much higher numbers, OpenCL may prove even more distinguished in the coming years.

    Transistor harvest

    Collectively, the concurrency-enabling features introduced in Snow Leopard picture the biggest boost to asynchronous and parallel software evolution in any Mac OS X release—perhaps in any desktop operating system release ever. It may subsist arduous for end-users to Get excited about "plumbing" technologies love august Central Dispatch and OpenCL, let solitary compilers and programming language features, but it's upon these foundations that developers will create ever-more-impressive edifices of software. And if those applications tower over their synchronous, serial predecessors, it will subsist because they stand on the shoulders of giants.

    QuickTime Player's novel icon (Not a fan)QuickTime Player's novel icon (Not a fan) QuickTime Player

    There's been some confusion surrounding QuickTime in Snow Leopard. The earlier section about QuickTime X explains what you requisite to know about the present and future of QuickTime as a technology and an API. But a few of Apple's decisions—and the extremely overloaded significance of the word "QuickTime" in the minds of consumers—have blurred the picture somewhat.

    The first head-scratcher occurs during installation. If you betide to click on the "Customize…" button during installation, you'll see the following options:

    QuickTime 7 is an optional install?QuickTime 7 is an optional install?

    We've already talked about Rosetta being an optional install, but QuickTime 7 too? Isn't QuickTime severely crippled without QuickTime 7? Why in the world would that subsist an optional install?

    Well, there's no requisite to panic. That item in the installer should actually read "QuickTime Player 7." QuickTime 7, the veteran but extremely capable media framework discussed earlier, is installed by default in Snow Leopard—in fact, it's mandatory. But the player application, the one with the veteran blue "Q" icon, the one that many casual users actually speculate of as being "QuickTime," that's been replaced with a novel QuickTime-X-savvy version sporting a pudgy novel icon (see above right).

    The novel player application is a astronomical departure from the old. Obviously, it leverages QuickTime X for more efficient video playback, but the user interface is also completely new. Gone are the gray edge and bottom-mounted playback controls from the veteran QuickTime Player, replaced by a frameless window with a black title bar and a floating, moveable set of controls.

    The novel QuickTime Player: boldly going where <a href="">NicePlayer</a> has gone before Enlarge / The novel QuickTime Player: boldly going where NicePlayer has gone before

    It's love a combination of the window treatment of the excellent NicePlayer application and the full-screen playback controls from the veteran QuickTime Player. I'm a bit bothered by two things. First, the ever-so-slightly clipped corners appear love a heinous idea. Am I just reputed to give up those dozen-or-so pixels? NicePlayer does it right, showing crisp, square corners.

    Second, the floating playback controls obscure the movie. What if I'm scrubbing around looking for something in that portion of the frame? Yes, you can fling the controls, but what if I'm looking for something in an unknown location in the frame? Also, the title bar obscures an entire swath of the top of the frame, and this can't subsist moved. I treasure the compactness of this approach, but it'd subsist nice if the title bar overlap could subsist disabled and the controls could subsist dragged off the movie entirely and docked to the bottom or something.

    (One blessing for people who share my OCD tendencies: if you fling the floating controls, they don't recollect their position the next time you open a movie. Why is that a blessing? Because if it worked the other way, we'd entire spend artery too much time fretting about their inability to restore the controller to its default, precisely centered position. Sad, but true.)

    The novel QuickTime Player presents a decidedly iMovie-like (or is it iPhone-like, nowadays?) interface for trimming video. Still-frame thumbnails are placed side-by-side to form a timeline, with adjustable stops at each abide for trimming.

    Trimming in the novel QuickTime Player Enlarge / Trimming in the novel QuickTime Player

    Holding down the option key changes from a thumbnail timeline to an audio waveform display:

    Trimming with audio waveform view Enlarge / Trimming with audio waveform view

    In both the video and audio cases, I maintain to sensation exactly how useful the fancy timeline appearances are. The audio waveform is quite tiny and compressed, and the limited horizontal space of the in-window display means a movie can only reveal a handful of video frames in its timeline. Also, if there's any competence to execute fine adjustments using something other than extremely heedful mouse movements (which are necessarily theme to a limited resolution) then I couldn't find it. Final sever Pro this is not.

    QuickTime Player has learned another novel trick: screen recording. The controls are limited, so more demanding users will silent maintain a requisite for a full-featured screen recorder, but QuickTime Player gets the job done.

    Screen recording in QuickTime PlayerScreen recording in QuickTime Player

    There's also an audio-only option, with a similarly simplified collection of settings.

    Audio recordingAudio recording

    Finally, the novel QuickTime Player has the competence to upload a movie directly to YouTube and MobileMe, forward one via e-mail, or add it to your iTunes library. The export options are also vastly simplified, with preset options for iPhone/iPod, Apple TV, and HD 480p and 720p.

    Unfortunately, the list of things you can't execute with the novel QuickTime Player is quite long. You can't cut, copy, and paste whimsical portions of a movie (trimming only affects the ends); you can't extract or delete individual tracks or overlay one track onto another (optionally scaling to fit); you can't export a movie by choosing from the complete set of available QuickTime audio and video codecs. entire of these things were feasible with the veteran QuickTime Player—if, that is, you paid the $30 for a QuickTime Pro license. In the past, I've described this extra fee as "criminally stupid", but the features it enabled in QuickTime Player were really useful.

    It's tempting to impute their absence in the novel QuickTime Player to the previously discussed limitations of QuickTime X. But the novel QuickTime Player is built on top of QTKit, which serves as a front-end for both QuickTime X and QuickTime 7. And it does, after all, feature some limited editing features love trimming, plus some previously "Pro"-only features love full-screen playback. Also, the novel QuickTime Player can indeed play movies using third-party plug-ins—a feature clearly powered by QuickTime 7.

    Well, Snow Leopard has an extremely pleasant dumbfound waiting for you if you install the optional QuickTime Player 7. When I did so, what I got was the veteran QuickTime Player—somewhat insultingly installed in the "Utilities" folder—with entire of its "Pro" features permanently unlocked. Yes, the tyranny of QuickTime Pro seems to subsist at an end…

    QuickTime Pro: now free for everyone?QuickTime Pro: now free for everyone?

    …but perhaps the key word above is "seems," because QuickTime Player 7 does not maintain entire "pro" features unlocked for everyone. I installed Snow Leopard onto an blank disk, and QuickTime 7 was not automatically installed (as it is when the installer detects an existing QuickTime Pro license on the target disk). After booting from my fresh Snow Leopard volume, I manually installed the "QuickTime 7" optional component using the Snow Leopard installer disk.

    The result for me was a QuickTime Player 7 application with entire pro features unlocked and with no visible QuickTime Pro registration information. I did, however, maintain a QuickTime Pro license on one of the attached drives. Apparently, the installer detected this and gave me an unlocked QuickTime Player 7 application, even though the boot volume never had a QuickTime Pro license on it.

    The Dock

    The novel appearance of some aspects of the Dock are accompanied by some novel functionality as well. Clicking and holding on a running application's Dock icon now triggers Expos�, but only for the windows belonging to that application. Dragging a file onto a docked application icon and holding it there for a bit produces the selfsame result. You can then continue that selfsame drag onto one of the Exposé window thumbnails and hover there a bit to bring that window to the front and drop the file into it. It's a pretty handy technique, once you Get in the habit of doing it.

    The Exposé display itself is also changed. Now, minimized windows are displayed in smaller form on the bottom of the screen below a thin line.

    Dock Exposé with novel placement of minimized windows Enlarge / Dock Exposé with novel placement of minimized windows

    In the screenshot above, you'll notice that notanyone of the minimized windows issue in my Dock. That's thanks to another welcome addition: the competence to minimize windows "into" the application icon. You'll find the setting for this in the Dock's preference pane.

    New Dock preference: Minimize windows into application iconNew Dock preference: Minimize windows into application icon Minimized windows in a Dock application menuMinimized window denoted by a diamond

    Once set, minimized windows will slip behind the icon of their parent application and then disappear. To Get them back, either right-click the application icon (see right) or trigger Exposé.

    The Dock's grid view for folders now incorporates a scroll bar when there are too many items to proper comfortably. Clicking on a folder icon in the grid now shows that folder's contents within the grid, allowing you to navigate down several folders to find a buried item. A tiny "back" navigation button appears once you descend.

    These are entire useful novel behaviors, and quite a prize considering the reputed "no novel features" stance of Snow Leopard. But the fundamental nature of the Dock remains the same. Users who want a more elastic or more powerful application launcher/folder organizer/window minimization system must silent either sacrifice some functionality (e.g., Dock icon badges and bounce notifications) or continue to expend the Dock in addition to a third-party application.

    The option to support minimized windows from cluttering up the Dock was long overdue. But my enthusiasm is tempered by my frustration at the continued inability to click on a docked folder and maintain it open in the Finder, while also retaining the competence to drag items into that folder. This was the default behavior for docked folders for the first six years of Mac OS X's life, but it changed in Leopard. Snow Leopard does not better matters.

    Docking an alias to a folder provides the single-click-open behavior, but items cannot subsist dragged into a docked folder alias for some inexplicable reason. (Radar 5775786, closed in March 2008 with the terse explanation, "not currently supported.") Worse, dragging an item to a docked folder alias looks love it will work (the icon highlights) but upon release, the dragged item simply springs back to its original location. I really hoped this one would Get fixed in Snow Leopard. No such luck.

    Dock grid view's in-place navigation with back buttonDock grid view's in-place navigation with back button The Finder

    One of the earliest leaked screenshots of Snow Leopard included an innocuous-looking "Get Info…" window for the Finder, presumably to reveal that its version number had been updated to 10.6. The more thoughtprovoking tidbit of information it revealed was that the Finder in Snow Leopard was a 64-bit application.

    The Mac OS X Finder started its life as the designated "dog food" application for the Carbon backward-compatibility API for Mac OS X. Over the years, the Finder has been a frequent target of dissatisfaction and scorn. Those heinous feelings frequently spilled over into the parallel debate over API supremacy: Carbon vs. Cocoa.

    "The Finder sucks because it's a Carbon app. What they requisite is a Cocoa Finder! Surely that will unravel entire their woes." Well, Snow Leopard features a 64-bit Finder, and as they entire know, Carbon was not ported to 64-bit. Et voila! A Cocoa Finder in Snow Leopard. (More on the woes in a bit.)

    The conversion to Cocoa followed the Snow Leopard formula: no novel features… except for maybe one or two. And so, the "new" Cocoa Finder looks and works almost exactly love the veteran Carbon Finder. The biggest indicator of its "Cocoa-ness" is the extensive expend of Core Animation transitions. For example, when a Finder window does its schizophrenic transformation from a sidebar-bedecked browser window to its minimally-adorned form, it no longer happens in a blink. Instead, the sidebar slides away and fades, the toolbar shrinks, and everything tucks in to form its novel shape.

    Despite crossing the line in a few cases, the Core Animation transitions execute fabricate the application feel more polished, and yes, "more Cocoa." And presumably the expend of Cocoa made it so darn simple to add features that the developers just couldn't resist throwing in a few.

    The number-one feature request from hefty column-view users has finally been implemented: sortable columns. The sort order applies to entire columns at once, which isn't as nice as per-column sorting, but it's much better than nothing at all. The sort order can subsist set using a menu command (each of which has a keyboard shortcut) or by right-clicking in an unoccupied locality of a column and selecting from the resulting context menu.

    Column view sorting context menu Enlarge / Column view sorting context menu Column view sorting menu Enlarge / Column view sorting menu

    Even the lowly icon view has been enhanced in Snow Leopard. Every icon-view window now includes a tiny slider to control the size of the icons.

    The Finder's icon view with its novel slider controlThe Finder's icon view with its novel slider control

    This may appear a bit odd—how often execute people change icon sizes?—but it makes much more sense in the context of previewing images in the Finder. This expend case is made even more apposite by the recent expansion of the maximum icon size to 512x512 pixels.

    The icon previews themselves maintain been enhanced to better match the abilities available in Quick Look. outcome it entire together and you can smoothly zoom a tiny PDF icon, for example, into the impressively high-fidelity preview shown below, complete with the competence to eddy pages. One press of the space bar and you'll progress to the even larger and more elastic Quick survey view. It's a pretty smooth experience.

    Not your father's icon: 512x512 pixels of multi-page PDF previewingNot your father's icon: 512x512 pixels of multi-page PDF previewing

    QuickTime previews maintain been similarly enhanced. As you zoom in on the icon, it transforms into a miniature movie player, adorned with an odd circular progress indicator. Assuming users are willing to wrangle with the vagaries of the Finder's view settings successfully enough to Get icon view to stick for the windows where it's most useful, I speculate that odd tiny slider is actually going to Get a lot of use.

    The Finder's QuickTime preview. (The "glare" overlay is a bit much.)The Finder's QuickTime preview. (The "glare" overlay is a bit much.)

    List view also has a few enhancements—accidental, incidental, or otherwise. The drag locality for each list view item now spans the entire line. In Leopard, though the entire line was highlighted, only the file name or icon portion could subsist dragged. Trying to drag anywhere else just extended the selection to other items in the list view as the cursor was moved. I'm not positive whether this change in behavior is intentional or if it's just an unexamined consequence of the underlying control used for list view in the novel Cocoa Finder. Either way, thumbs up.

    Double-clicking on the dividing line between two column headers in list view will "right-size" that column. For most columns, this means expanding or shrinking to minimally proper the widest value in the column. Date headers will progressively shrink to reveal less verbose date formats. Supposedly, this worked intermittently in Leopard as well. But whether Cocoa is bringing this feature for the first time or is just making it work correctly for the first time, it's a change for the better.

    Searching using the Finder's browser view is greatly improved by the implementation of one of those tiny things that many users maintain been clamoring for year after year. There's now a preference to select the default scope of the search realm in the Finder window toolbar. Can I Get an amen?

    Default Finder search location: configurable at last.Default Finder search location: configurable at last.

    Along similar lines, there are other long-desired enhancements that will Go a long artery towards making the desktop environment feel more solid. A pleasurable case is the improved handling of the dreaded "cannot eject, disk in use" error. The obvious follow-up question from the user is, "Okay, so what's using it?" Snow Leopard finally provides that information.

    No more guessingNo more guessing

    (Yes, Mac OS X will rebuff to expel a disk if your current working directory in a command-line shell is on that disk. kind of cool, but also kind of annoying.)

    Another feasible user response to a disk-in-use mistake is, "I don't care. I'm in a hurry. Just expel it!" That's an option now as well.

    Forcible ejection in progressForcible ejection in progress

    Hm, but why did I Get information about the offending application in one dialog, an option to compel ejection in the other, but neither one presented both choices? It's a mystery to me, but presumably it's related to exactly what information the Finder has about the contention for the disk. (As always, the lsof command is available if you want to device it out the old-fashioned way.)


    So does the novel Cocoa Finder finally exile entire of those embarrassing bugs from the bad-old days of Carbon? Not quite. This is essentially the "1.0" release of the Cocoa Finder, and it has its share of 1.0 bugs. Here's one discovered by Glen Aspeslagh (see image right).

    Do you see it? If not, survey closer at the order of the dates in the supposedly sorted "Date Modified" column. So yeah, that veteran Finder magic has not been entirely extinguished.

    There also remains some weirdness in the operation of the icon grid. In a view where grid snap is turned on (or is enabled transiently by holding down the command key during a drag) icons appear terrified of each other, leaving huge distances between themselves and their neighbors when they select which grid spot to snap to. It's as if the Finder lives in mortal terror that one of these files will someday Get a 200-character filename that will overlap with a neighboring file's name.

    The worst incarnation of this behavior happens along the privilege edge of the screen where mounted volumes issue on the desktop. (Incidentally, this is not the default; if you want to see disks on your desktop, you must enable this preference in the Finder.) When I mount a novel disk, I'm often surprised to see where it ends up appearing. If there are any icons remotely proximate to the privilege edge of the screen, the disk icon will rebuff to issue there. Again, the Finder is not avoiding any actual name or icon overlapping. It appears to subsist avoiding the mere possibility of overlapping at some unspecified point in the future. Silly.

    Finder report card

    Overall, the Snow Leopard Finder takes several significant steps forward—64-bit/Cocoa future-proofing, a few new, useful features, added polish—and only a few shuffles backwards with the slight overuse of animation and the continued presence of some puzzling bugs. Considering how long it took the Carbon Finder to Get to its pre-Snow-Leopard feature set and level of polish, it's quite an achievement for a Cocoa Finder to match or exceed its predecessor in its very first release. I'm positive the Carbon vs. Cocoa warriors would maintain had a realm day with that statement, were Carbon not outcome out to pasture in Leopard. But it was, and to the victor Go the spoils.


    Snow Leopard's headline "one novel feature" is champion for Microsoft Exchange. This appears to be, at least partially, yet another hand-me-down from the iPhone, which gained champion for Exchange in its 2.0 release and expanded on it in 3.0. Snow Leopard's Exchange champion is weaved throughout the expected crop of applications in Mac OS X: iCal, Mail, and Address Book.

    The astronomical caveat is that it will only work with a server running Exchange 2007 (Service Pack 1, Update Rollup 4) or later. While I'm positive Microsoft greatly appreciates any additional upgrade revenue this decision provides, it means that for users whose workplaces are silent running older versions of Exchange, Snow Leopard's "Exchange support" might as well not exist.

    Those users are probably already running the only other viable Mac OS X Exchange client, Microsoft Entourage, so they'll likely just sit tense and wait for their IT departments to upgrade. Meanwhile, Microsoft is already making overtures to these users with the promised creation—finally—of an honest-to-goodness version of Outlook for Mac OS X.

    In my admittedly brief testing, Snow Leopard's Exchange champion seems to work as expected. I had to maintain one of the Microsoft mavens in the Ars Orbiting HQ spin up an Exchange 2007 server just for the purposes of this review. However it was configured, entire I had to enter in the Mail application was my complete name, e-mail address, and password, and it automatically discovered entire apposite settings and configured iCal and Address reserve for me.

    Exchange setup: surprisingly easyExchange setup: surprisingly easy

    Windows users are no doubt accustomed to this kind of Exchange integration, but it's the first time I've seen it on the Mac platform—and that includes my many years of using Entourage.

    Access to Exchange-related features is decidedly subdued, in keeping with the existing interfaces for Mail, iCal, and Address Book. If you're expecting the swarm of panels and toolbar buttons institute in Outlook on Windows, you're in for a bit of a shock. For example, here's the "detail" view of a meeting in iCal.

    iCal event detailiCal event detail

    Clicking the "edit" button hardly reveals more.

    Event editor: that's it?Event editor: that's it?

    The "availability" window also includes the bare minimum number of controls and displays to Get the job done.

    Meeting availability checker Enlarge / Meeting availability checker

    The integration into Mail and Address reserve is even more subtle—almost entirely transparent. This is to subsist construed as a feature, I suppose. But though I don't know enough about Exchange to subsist completely sure, I can't quake the fire that there are Exchange features that remain inaccessible from Mac OS X clients. For example, how execute I reserve a "resource" in a meeting? If there's a artery to execute so, I couldn't learn it.

    Still, even basic Exchange integration out-of-the-box goes long artery towards making Mac OS X more welcome in corporate environments. It remains to subsist seen how convinced IT managers are of the "realness" of Snow Leopard's Exchange integration. But I've got to speculate that being able to forward and receive mail, create and respond to meeting invitations, and expend the global corporate address reserve is enough for any Mac user to Get along reasonably well in an Exchange-centric environment.


    The thing is, there's not really much to snarl about performance in Snow Leopard. Dozens of benchmark graphs lead to the selfsame simple conclusion: Snow Leopard is faster than Leopard. Not shockingly so, at least in the aggregate, but it's faster. And while isolating one particular subsystem with a micro-benchmark may reveal some impressive numbers, it's the artery these tiny changes combine to better the real-world undergo of using the system that really makes a difference.

    One case Apple gave at WWDC was making an initial Time Machine backup over the network to a Time Capsule. Apple's approach to optimizing this operation was to address each and every subsystem involved.

    Time Machine itself was given champion for overlapping i/o. Spotlight indexing, which happens on Time Machine volumes as well, was identified as another time-consuming assignment involved in backups, so its performance was improved. The networking code was enhanced to purchase edge of hardware-accelerated checksums where possible, and the software checksum code was hand-tuned for maximum performance. The performance of HFS+ journaling, which accompanies each file system metadata update, was also improved. For Time Machine backups that write to disk images rather than native HFS+ file systems, Apple added champion for concurrent access to disk images. The amount of network traffic produced by AFP during backups has also been reduced.

    All of this adds up to a respectable 55% overall improvement in the hasten of an initial Time Machine backup. And, of course, the performance improvements to the individual subsystems profit entire applications that expend them, not just Time Machine.

    This holistic approach to performance improvement is not likely to knock anyone's socks off, but every time you Run across a piece of functionality in Snow Leopard that disproportionately benefits from one of these optimized subsystems, it's a pleasure.

    For example, Snow Leopard shuts down and restarts much faster than Leopard. I'm not talking about boot time; I connote the time between the selection of the Shutdown or Restart command and when the system turns off or begins its novel boot cycle. Leopard doesn't purchase long at entire to execute this; only a few dozen of seconds when there are no applications open. But in Snow Leopard, it's so hastily that I often thought the operating system had crashed rather than shut down cleanly. (That's actually not too far from the truth.)

    The performance boosts offered by earlier major releases of Mac OS X silent dwarf Snow Leopard's speedup, but that's mostly because Mac OS X was so excruciatingly sluggish in its early years. It's simple to create a astronomical performance delta when you're starting from something abysmally slow. The fact that Snow Leopard achieves consistent, measurable improvements over the already-speedy Leopard is entire the more impressive.

    And yes, for the seventh consecutive time, a novel release of Mac OS X is faster on the selfsame hardware than its predecessor. (And for the first time ever, it's smaller, too.) What more can you inquire for, really? Even that veteran performance bugaboo, window resizing, has been completely vanquished. Grab the corner of a fully-populated iCal window—the worst-case scenario for window resizing in the veteran days—and quake it as hastily as you can. Your cursor will never subsist more than a few millimeters from the window's grab handle; it tracks your frantic motion perfectly. On most Macs, this is actually suitable in Leopard as well. It just goes to reveal how far Mac OS X has arrive on the performance front. These days, they entire just purchase it for granted, which is exactly the artery it should be.

    Grab bag

    In the "grab bag" section, I usually examine smaller, mostly unrelated features that don't warrant full-blown sections of their own. But when it comes to user-visible features, Snow Leopard is kind of "all grab bag," if you know what I mean. Apple's even got its own incarnation in the form of a giant webpage of "refinements." I'll probably overlap with some of those, but there'll subsist a few novel ones here as well.

    New columns in open/save dialogs

    The list view in open and reclaim dialog boxed now supports more than just "Name" and "Date Modified" columns. Right-click on any column to Get a option of additional columns to display. I've wanted this feature for a long time, and I'm glad someone finally had time to implement it.

    Configurable columns in open/save dialogsConfigurable columns in open/save dialogs Improved scanner support

    The bundled Image Capture application now has the competence to talk to a wide range of scanners. I plugged in my Epson Stylus CX7800, a device that previously required the expend of third-party software in order to expend the scanning feature, and Image Capture detected it immediately.

    Epson scanner + Image Capture - Epson software Enlarge / Epson scanner + Image Capture - Epson software

    Image Capture is also not a heinous tiny scanning application. It has pretty pleasurable automatic kick detection, including champion for multiple objects, obviating the requisite to manually crop items. Given the sometimes-questionable property of third-party printer and scanner drivers for Mac OS X, the competence to expend a bundled application is welcome.

    System Preferences bit wars

    System Preferences, love virtually entire other applications in Snow Leopard, is 64-bit. But since 64-bit applications can't load 32-bit plug-ins, that presents a problem for the existing crop of 32-bit third-party preference panes. System Preferences handles this situation with a reasonable amount of grace. On launch, it will display icons for entire installed preference panes, 64-bit or 32-bit. But if you click on a 32-bit preference pane, you'll subsist presented with a notification love this:

    64-bit application vs. 32-bit plug-in: fight!64-bit application vs. 32-bit plug-in: fight!

    Click "OK" and System Preferences will relaunch in 32-bit mode, which is conveniently indicated in the title bar. Since entire of the first-party preference panes are compiled for both 64-bit and 32-bit operation, System Preferences does not requisite to relaunch again for the duration of its use. This raises the question, why not maintain System Preferences launch in 32-bit mode entire the time? I suspect it's just another artery for Apple to "encourage" developers to build 64-bit-compatible binaries.

    Safari plug-ins

    The inability of of 64-bit applications load 32-bit plug-ins is a problem for Safari as well. Plug-ins are so distinguished to the Web undergo that relaunching in 32-bit mode is not really an option. You'd probably requisite to relaunch as soon as you visited your first webpage. But Apple does want Safari to Run in 64-bit mode due to some significant performance enhancements in the JavaScript engine and other areas of the application that are not available in 32-bit mode.

    Apple's solution is similar to what it did with QuickTime X and 32-bit QuickTime 7 plug-ins. Safari will Run 32-bit plug-ins in divorce 32-bit processes as needed.

    Separate processes for 32-bit Safari plug-insSeparate processes for 32-bit Safari plug-ins

    This has the added, extremely significant profit of isolating potentially buggy plug-ins. According to the automated crash reporting built into Mac OS X, Apple has said that the number one intuition of crashes is Web browser plug-ins. That's not the number one intuition of crashes in Safari, reason you, it's the number one intuition when considering entire crashes of entire applications in Mac OS X. (And though it was not mentioned by name, I speculate they entire know the primary culprit.)

    As you can see above, the QuickTime browser plug-in gets the selfsame treatment as flash and other third-party 32-bit Safari plug-ins. entire of this means that when a plug-in crashes, Safari in Snow Leopard does not. The window or tab containing the crashing plug-in doesn't even close. You can simply click the reload button and give the problematic plug-in another desultory to duty correctly.

    While this is silent far from the much more robust approach employed by Google Chrome, where each tab lives in its own independent process, if Apple's crash statistics are to subsist believed, isolating plug-ins may generate most of the profit of truly divorce processes with a significantly less radical change to the Safari application itself.

    Resolution independence

    When they final left Mac OS X in its seemingly interminable march towards a truly scalable user interface, it was almost ready for prime time. I'm heart-broken to snarl that resolution independence was obviously not a priority in Snow Leopard, because it hasn't gotten any better, and may maintain actually regressed a bit. Here's what TextEdit looks love at a 2.0 scale factor in Leopard and Snow Leopard.

    TextEdit at scale factor 2.0 in LeopardTextEdit at scale factor 2.0 in Leopard TextEdit at scale factor 2.0 in Snow LeopardTextEdit at scale factor 2.0 in Snow Leopard

    Yep, it's a bummer. I silent recollect Apple advising developers to maintain their applications ready for resolution independence by 2008. That's one of the few dates that the Jobs-II-era Apple has not been able to hit, and it's getting later entire the time. On the other hand, it's not love 200-DPI monitors are raining from the sky either. But I'd really love to see Apple Get going on this. It will undoubtedly purchase a long time for everything to survey and work correctly, so let's Get started.

    Terminal splitters

    The Terminal application in Tiger and earlier versions of Mac OS X allowed each of its windows to subsist split horizontally into two divorce panes. This was invaluable for referencing some earlier text in the scrollback while also typing commands at the prompt. Sadly, the splitter feature disappeared in Leopard. In Snow Leopard, it's back with a vengeance.

    Arbitrary splitters, baby!Arbitrary splitters, baby!

    (Now if only my favorite text editor would Get on board the train to splittersville.)

    Terminal in Snow Leopard also defaults to the novel Menlo font. But wayward to earlier reports, the One suitable Monospaced Font, Monaco, is most definitely silent included in Snow Leopard (see screenshot above) and it works just fine.

    System Preferences shuffle

    The seemingly obligatory rearrangement of preference panes in the System Preferences application accompanying each release of Mac OS X continues in Snow Leopard.

    System Preferences: shuffled yet again Enlarge / System Preferences: shuffled yet again System Preferences (not running) with Dock menuSystem Preferences (not running) with Dock menu

    This time, the "Keyboard & Mouse" preference pane is split into divorce "Keyboard" and "Mouse" panes, "International" becomes "Language & Text," and the "Internet & Network" section becomes "Internet & Wireless" and adopts the Bluetooth preference pane.

    Someday in the remote future, perhaps Apple will finally arrive at the "ultimate" arrangement of preference panes and they can entire finally Go more than two years without their muscle reminiscence being disrupted.

    Before stirring on, System Preferences has one antiseptic trick. You can launch directly into a specific preference pane by right-clicking on System Preferences's Dock icon. This works even when System Preferences is not yet running. kind of creepy, but useful.

    Core location

    One more gift from the iPhone, Core Location, allows Macs to device out where in the world they are. The "Date & Time" preference pane offers to set your time zone automatically based on your current location using this newfound ability.

    Set your Mac's time zone automatically based on your current location, thanks to Core Location.Set your Mac's time zone automatically based on your current location, thanks to Core Location. Keyboard magic

    Snow Leopard includes a simple facility for system-wide text auto-correction and expansion, accessible from the "Language & Text" preference pane. It's not quite ready to give a dedicated third-party application a Run for its money, but hey, it's free.

    Global text expansion and auto-correction Enlarge / Global text expansion and auto-correction

    The keyboard shortcuts preference pane has also been rearranged. Now, instead of a single, long list of system-wide keyboard shortcuts, they're arranged into categories. This reduces clutter, but it also makes it a bit more difficult to find the shortcut you're interested in.

    Keyboard shortcuts: now with categories Enlarge / Keyboard shortcuts: now with categories The sleeping Mac dilemma

    I don't love to leave my Mac Pro turned on 24 hours a day, especially during the summer in my un-air-conditioned house. But I execute want to maintain access to the files on my Mac when I'm elsewhere—at work, on the road, etc. It is feasible to wake a sleeping Mac remotely, but doing so requires being on the selfsame local network.

    My solution has been to leave a smaller, more power-efficient laptop on at entire times on the selfsame network as my Mac Pro. To wake my Mac Pro remotely, I ssh into the laptop, then forward the magic "wake up" packet to my Mac Pro. (For this to work, the "Wake for Ethernet network administrator access" checkbox must subsist checked in the "Energy Saver" preference pane in System Preferences.)

    Snow Leopard provides a artery to execute this without leaving any of my computers running entire day. When a Mac running Snow Leopard is outcome to sleep, it attempts to hand off ownership of its IP address to its router. (This only works with an AirPort Extreme groundwork station from 2007 or later, or a Time Capsule from 2008 or later with the latest (7.4.2) firmware installed.) The router then listens for any attempt to connect to the IP address. When one occurs, it wakes up the original owner, hands back the IP address, and forwards traffic appropriately.

    You can even wake some recent-model Macs over WiFi. Combined with MobileMe's "Back to My Mac" dynamic DNS thingamabob, it means I can leave entire my Macs asleep and silent maintain access to their contents anytime, anywhere.

    Back to my hack

    As has become traditional, this novel release of Mac OS X makes life a bit harder for developers whose software works by patching the in-memory representation of other running applications or the operating system itself. This includes Input Managers, SIMBL plug-ins, and of course the dreaded "Haxies."

    Input Managers Get the worst of it. They've actually been unsupported and non-functional in 64-bit applications since Leopard. That wasn't such a astronomical deal when Mac OS X shipped with a whopping two 64-bit applications. But now, with almost every application in Snow Leopard going 64-bit, it's suddenly very significant.

    Thanks to Safari's lack of an officially sanctioned extension mechanism, developers looking to enhance its functionality maintain most often resorted to the expend of Input Managers and SIMBL (which is an Input-Manager-based framework). A 64-bit Safari puts a damper on that entire market. Though it is feasible to manually set Safari to launch in 32-bit mode—Get Info on the application in the Finder and click a checkbox—ideally, this is not something developers want to compel users to do.

    Happily, at least one commonly used Safari enhancement has the pleasurable fortune to subsist built on top of the officially supported browser plug-in API used by Flash, QuickTime, etc. But that may not subsist a feasible approach for Safari extensions that enhance functionality in ways not tied directly to the display of particular types of content within a webpage.

    Though I blueprint to Run Safari in its default 64-bit mode, I'll really miss Saft, a Safari extension I expend for session restoration (yes, I know Safari has this feature, but it's activated manually—the horror) and address bar shortcuts (e.g., "w noodles" to survey up "noodles" in Wikipedia). I'm hoping that clever developers will find a artery to overcome this novel challenge. They always appear to, in the end. (Or Apple could add a proper extension system to Safari, of course. But I'm not holding my breath.)

    As for the Haxies, those usually atomize with each major operating system update as a matter of course. And each time, those determined fellows at Unsanity, against entire odds, manage to support their software working. I salute them for their effort. I delayed upgrading to Leopard for a long time based solely on the absence of my beloved WindowShade X. I hope I don't maintain to wait too long for a Snow-Leopard-compatible version.

    The general trend in Mac OS X is away from any sort of involuntary reminiscence space sharing, and towards "external" plug-ins that live in their own, divorce processes. Even contextual menu plug-ins in the Finder maintain been disabled, replaced by an enhanced, but silent less-powerful Services API. Again, I maintain faith that developers will adapt. But the waiting is the hardest part.


    It looks love we'll entire subsist waiting a while longer for a file system in shining armor to replace the venerable HFS+ (11 years young!) as the default file system in Mac OS X. Despite rumors, outright declarations, and much actual pre-release code, champion for the impressive ZFS file system is not present in Snow Leopard.

    That's a shame because Time Machine veritably cries out for some ZFS magic. What's more, Apple seems to agree, as evidenced by a post from an Apple employee to a ZFS mailing list final year. When asked about a ZFS-savvy implementation of Time Machine, the reply was encouraging: "This one is distinguished and likely will arrive sometime, but not for SL." ("SL" is short for Snow Leopard.)

    There are many reasons why ZFS (or a file system with similar features) is a impeccable proper for Time Machine, but the most distinguished is its competence to forward only the block-level changes during each backup. As Time Machine is currently implemented, if you fabricate a tiny change to a giant file, the entire giant file is copied to the Time Machine volume during the next backup. This is extremely wasteful and time consuming, especially for great files that are modified constantly during the day (e.g., Entourage's e-mail database). Time Machine running on top of ZFS could transfer just the changed disk blocks (a maximum of 128KB each in ZFS, and usually much smaller).

    ZFS would also bring vastly increased robustness for data and metadata, a pooled storage model, constant-time snapshots and clones, and a pony. People sometimes inquire what, exactly, is wrong with HFS+. Aside from its obvious lack of the features just listed, HFS+ is limited in many ways by its dated design, which is based on HFS, a twenty-five year-old file system.

    To give just one example, the centrally located Catalog File, which must subsist updated for each change to the file system's structure, is a frequent and inevitable source of contention. Modern file systems usually spread their metadata around, both for robustness (multiple copies are often kept in divorce locations on the disk) and to allow for better concurrency.

    Practically speaking, speculate about those times when you Run Disk Utility on an HFS+ volume and it finds (and hopefully repairs) a bunch of errors. That's bad, okay? That's something that should not betide with a modern, thoroughly checksummed, always-consistent-on-disk file system unless there are hardware problems (and a ZFS storage pool can actually deal with that as well). And yet it happens entire the time with HFS+ disks in Mac OS X when various bits of metadata Get corrupted or become out of date.

    Apple gets by year after year, tacking novel features onto HFS+ with duct tape and a prayer, but at a positive point there simply has to subsist a successor—whether it's ZFS, a home-grown Apple file system, or something else entirely. My fingers are crossed for Mac OS X 10.7.

    The future soon

    Creating an operating system is as much a gregarious exercise as a technological one. Creating a platform, even more so. entire of Snow Leopard's considerable technical achievements are not just designed to profit users; they're also intended to goad, persuade, and otherwise herd developers in the direction that Apple feels will subsist most beneficial for the future of the platform.

    For this to work, Snow Leopard has to actually find its artery into the hands of customers. The pricing helps a lot there. But even if Snow Leopard were free, there's silent some cost to the consumer—in time, worry, software updates, etc.—when performing a major operating system upgrade. The selfsame goes for developers who must, at the very least, certify that their existing applications Run correctly on the novel OS.

    The habitual artery to overcome this kind of upgrade hesitation has been to pack the OS with novel features. novel features sell, and the more copies of the novel operating system in use, the more motivated developers are to update their applications to not just Run on the novel OS, but also purchase edge of its novel abilities.

    A major operating system upgrade with "no novel features" must play by a different set of rules. Every party involved expects some counterbalance to the lack of novel features. In Snow Leopard, developers stand to reap the biggest benefits thanks to an impressive set of novel technologies, many of which cover areas previously unaddressed in Mac OS X. Apple clearly feels that the future of the platform depends on much better utilization of computing resources, and is doing everything it can to fabricate it simple for developers to fling in this direction.

    Though it's obvious that Snow Leopard includes fewer external features than its predecessor, I'd wager that it has just as many, if not more internal changes than Leopard. This, I fear, means that the initial release of Snow Leopard will likely suffer the typical 10.x.0 bugs. There maintain already been reports of novel bugs introduced to existing APIs in Snow Leopard. This is the exact antithetical of Snow Leopard's implied plight to users and developers that it would concentrate on making existing features faster and more robust without introducing novel functionality and the accompanying novel bugs.

    On the other side of the coin, I imagine entire the teams at Apple that worked on Snow Leopard absolutely reveled in the break to polish their particular subsystems without being burdened by supporting the marketing-driven feature-of-the-month. In any long-lived software product, there needs to subsist this kind of release valve every few years, lest the entire code groundwork Go off into the weeds.

    There's been one other "no novel features" release of Mac OS X. Mac OS X 10.1, released a mere six months after version 10.0, was handed out for free by Apple at the 2001 Seybold publishing conference and, later, at Apple retail stores. It was also available from Apple's online store for $19.95 (along with a copy of Mac OS 9.2.1 for expend in the Classic environment). This was a different time for Mac OS X. Versions 10.0 and 10.1 were slow, incomplete, and extremely immature; the transition from classic Mac OS was far from over.

    Judged as a modern incarnation of the 10.1 release, Snow Leopard looks pretty darned good. The pricing is similar, and the benefits—to developers and to users—are greater. So is the risk. But again, that has more to execute with how horrible Mac OS X 10.0 was. Choosing not to upgrade to 10.1 was unthinkable. Waiting a while to upgrade to Snow Leopard is reasonable if you want to subsist positive that entire the software you care about is compatible. But don't wait too long, because at $29 for the upgrade, I expect Snow Leopard adoption to subsist quite rapid. Software that will Run only on Snow Leopard may subsist here before you know it.

    Should you buy Mac OS X Snow Leopard? If you're already running Leopard, then the respond is a resounding "yes." If you're silent running Tiger, well, then it's probably time for a novel Mac anyway. When you buy one, it'll arrive with Snow Leopard.

    As for the future, it's tempting to view Snow Leopard as the "tick" in a novel Intel-style "tick-tock" release strategy for Mac OS X: radical novel features in version 10.7 followed by more Snow-Leopard-style refinements in 10.8, and so on, alternating between "feature" and "refinement" releases. Apple has not even hinted that they're considering this sort of plan, but I speculate there's a lot to recommend it.

    Snow Leopard is a unique and sparkling release, unlike any that maintain arrive before it in both scope and intention. At some point, Mac OS X will surely requisite to Get back on the bullet-point-features bandwagon. But for now, I'm content with Snow Leopard. It's the Mac OS X I know and love, but with more of the things that fabricate it feeble and abnormal engineered away.

    Snowy eyes Looking back

    This is the tenth review of a complete Mac OS X release, public beta, or developer preview to Run on Ars, dating back to December 1999 and Mac OS X DP2. If you want to jump into the Wayback Machine and see how far Apple has arrive with Snow Leopard (or just want to bone up on entire of the astronomical cat monikers), we've gone through the archives and dug up some of their older Mac OS X articles. happy reading!

  • Five years of Mac OS X, March 24, 2006
  • Mac OS X 10.5 Leopard, October 28, 2007
  • Mac OS X 10.4 Tiger, April 28, 2005
  • Mac OS X 10.3 Panther, November 9, 2003
  • Mac OS X 10.2 Jaguar, September 5, 2002
  • Mac OS X 10.1 (Puma), October 15, 2001
  • Mac OS X 10.0 (Cheetah), April 2, 2001
  • Mac OS X Public Beta, October 3, 2000
  • Mac OS X Q & A, June 20, 2000
  • Mac OS X DP4, May 24, 2000
  • Mac OS X DP3: tribulation by Water, February 28, 2000
  • Mac OS X Update: Quartz & Aqua, January 17, 2000
  • Mac OS X DP2, December 14, 1999

  • Discovering Mac OS X 10.6 Snow Leopard | existent questions and Pass4sure dumps

    See what Apple gives you in this Mac OS X update for just $29. You won't see astronomical interface changes, but there has been a lot of work done under the hood. Eric Geier discusses most of the performance enhancements and novel features.

    Like this article? They recommend 

    Apple released an update to the Mac OS X operating system (OS), Snow Leopard, at the abide of August. This makes it version 10.6. Although it might not maintain as many visual changes as Windows 7 does from Vista, it does maintain many notable enhancements and additions. The first thing you'll probably notice is the price: It's only $29 to upgrade from version 10.5.

    Since Tiger, Apple has been adding more and more 64-bit support. The Mac OS X kernel in Snow Leopard and most of the OS applications maintain been rebuilt to Run at 64-bit in addition to 32-bit. However, this excludes iTunes, Front Row, Grapher, and DVD Player applications. Plus privilege now only a select number of Apple computers are compatible with entire the added support.

    If you aren't a power user and maintain a typical 32-bit processor, this doesn't attend you out. But if you execute invest in a more powerful system, Mac OS X is ready more than ever.

    Running a 64-bit processor means it can process bigger chunks of data more quickly, giving you a faster, higher-performing computer.

    Mozilla to abide Firefox champion for OS X 10.6, 10.7, and 10.8 in August | existent questions and Pass4sure dumps

    Yesterday, Mozilla announced the abide of Firefox champion for Apple customers using Mac OS X versions 10.6, 10.7, and 10.8. The cutoff date is August 2016.

    Mozilla says it took this step following Apple's decision to abide champion for these OS X versions as well.

    Apple released Mac OS X 10.6 (Snow Leopard) in August 2009, Mac OS X 10.7 (Lion) in July 2011, and Mac OS X 10.8 (Mountain Lion) in July 2012. Apple announced the abide of official champion for Snow Leopard in February 2014, for Lion in October 2014, and for Mountain Lion in December 2014.

    Now, Mozilla is aphorism that, after August 2016, Firefox versions running on these operating systems will no longer receive novel features or security updates.

    Firefox ESR (Extended champion Release) will continue to champion these three OS versions until mid-August 2017, when it will also quit delivering novel features or security updates.

    At the start of the month, Google also pulled the plug on Google Chrome for OS X 10.6, 10.7, and 10.8, along with Windows XP and Vista.

    According to statistics at the abide of October 2015, notanyone of the aforementioned OS X versions had a market share above 10% among Mac users. The biggest chunk belonged to Snow Leopard, but most Mac users already started migrating to Mavericks (10.9), Yosemite (10.10) and El Capitan (10.11).

    "Mozilla strongly encourages their users to upgrade to a version of OS X currently supported by Apple. Unsupported operating systems receive no security updates, maintain known exploits, and are perilous for you to use," Mozilla advised customers yesterday.

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