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Running several programs at once - Mac Applications & Software

I just recently switched from the PC to the Mac (at home, unfortunately I still have to use Windoze at work, but that's another topic). I've been reading the David Pogue OS X missing manual and several times he says that you shouldn't close down any programs, because the Mac memory management will ensure they won't get in the way of your other active program. Is this really true? I'm a developer and I know that, at least in windows, any running program in a multitasking OS will be given it's own little slice of time to run, even if ...

  1. #1

    Default Running several programs at once

    I just recently switched from the PC to the Mac (at home,
    unfortunately I still have to use Windoze at work, but that's another
    topic). I've been reading the David Pogue OS X missing manual and
    several times he says that you shouldn't close down any programs,
    because the Mac memory management will ensure they won't get in the
    way of your other active program. Is this really true?

    I'm a developer and I know that, at least in windows, any running
    program in a multitasking OS will be given it's own little slice of
    time to run, even if it is doing nothing. Furthermore, if the program
    in the background is working on a large file (say a video file in
    iMovie or Final Cut Express), I don't see how it can NOT consume a lot
    of memory. The only thing I can think of is that if you close all
    open doents, the effect of a running background program will be
    small. I like to use photoshop and Final Cut Express on my Mac, but I
    always close down most of my open programs to ensure that they work at
    their best. Pogue seems to be saying this isn't necessary, is he
    right?
    Jason Guest

  2. #2

    Default Re: Running several programs at once

    Jason Carucci wrote:
     

    i think this advice dates from mac oses <= 9, and is a bit less valid than
    it once was.

    regardless, even now you can look at it two ways: as a resource issue, and
    as a ui issue.

    from a resource issue, regardless of os or version (we could even be talking
    about linux), it is a trade-off between the cost of restarting an app and
    the cost of maintaining it as an active process. in any os you could go
    look at a performance monitor to see how much memory and cpu it's taking.
    in any os you could see if you find the restart time to be onerous. then
    decide for yourself which course you want to take.

    from the ui standpoint, it is again a question of trade-offs and your
    prefernces. do you like the interaction of multiple idle/running apps, or
    do you like to run with a smaller set? fwiw, i think the mac ui might
    assume (because of its history) that multiple idle/running apps will be
    present.
    lefty Guest

  3. #3

    Default Re: Running several programs at once

    In article <google.com>, Jason
    Carucci <com> wrote:
     

    Congrats!
     

    Extremely poor advice -- mostly because of the "shouldn't" than
    anything else. There's no reason not to quit an app you're done with
    and won't be using again for a while. Of course, by the same token,
    there's no reason to quit an app you're going to use again in an hour.
    Leave it open so you can get to it quicker when you need it.
     

    Well, open the Terminal and type "top". This gives you the processor
    usage of your running apps. When I do this, most of my apps show 0.0%
    processor usage.
     

    Oh, it will. If it's actively working and consuming huge amounts of
    RAM, you'd be foolish not to expect other apps to show worse
    performance. However, due to the virtual memory scheme in OS X, every
    app has 2 GB of working RAM given to it. Any that is not in use but
    actually contains data will be paged off onto disk.
     

    Yes. You should be able to leave these apps open and, as long as they
    are not actually doing anything, they should not have an affect on the
    system. And since Photoshop, at least, opens slowly even on a 1 GHz
    machine, it's less of a hassle to just leave it running if you'll be
    using it again soon.

    --
    -Thomas

    <http://www.bitjuggler.com/>
    Thomas Guest

  4. #4

    Default Re: Running several programs at once

    Jason Carucci wrote: 

    A properly written app will block (not use CPU time) when it has nothing
    to do, and if you don't use it for a while, the memory it takes up
    will be swapped out, freeing your RAM for what you are using. So in
    principle this should be true, but it really comes down to what feels
    right to you.
     

    You can use Process Viewer to see how much CPU time an application is
    taking. For a properly written app that isn't doing anything, it should
    be 0%.
     

    It will consume a lot of memory, but if you aren't actively using the
    doent, its memory will be written to disk so that other progams can
    use your physical RAM.
     

    YMMV. :)

    -Peter

    Peter Guest

  5. #5

    Default Re: Running several programs at once

    In article <google.com>,
    com (Jason Carucci) wrote:
     

    Are you sure Pogue wasn't talking about running things in classic?

    --
    Regards,
    Jim Polaski
    "The measure of a man is what he will do while expecting that he will get nothing in return!"

    Macintosh for productivity. Linux for servers. Palm/Visor for mobility. Windows to feed the Black Hole in your IT budget

    Windows-the computer you need, Macintosh-The computer you Want!ant!i
    Jim Guest

  6. #6

    Default Re: Running several programs at once

    In article <google.com>,
    com (Jason Carucci) wrote:
     

    That's not actually what he says -- he says you don't HAVE TO close down
    any programs.

    And yes, it's true -- but obviously, if you have more RAM you can have
    more programs working simultaneously without a speed hit.
     

    If you're a developer, then surely you know the difference between
    processor time and RAM space. When a program is in the background, it
    will automatically get less of both than it would as the active program.
    OS X automatically and continuously re-allocated processor time and RAM
    based on the needs of the program weighted against the limits of the
    processor and RAM. Power-users can manually adjust this "traffic cop"
    using renice, but the auto settings seem to be fine for most people.
     

    Pogue is generally right, but you're correct that if you only have
    Photoshop open (for example), then the processor can give it MORE
    priority in terms of clock time and RAM than it could if you had a dozen
    programs open at once. Keep in mind that most people keep open programs
    that do not require a lot of power/RAM while in the background (a web
    browser, a word processor ...). If you've got some video program
    converting AVI to MPEG in the background and then try to run Photoshop,
    yes you're going to see a slowdown, but with a sufficiently powerful
    machine (like a dual G4 or G5) and a crapload o' RAM, it should be all
    that noticeable.
    --
    Cheers,
    _Chas_
    http://www.apple.com/switch
    non-spammers can write to chasm at mac (dot com)
    Charles Guest

  7. #7

    Default Re: Running several programs at once

    In article <google.com>,
    com (Jason Carucci) wrote:
     

    Others have covered the rest of your post, so I'll just hone in on
    what's left. I'm guessing that your development experience was not on
    preemptively multitasking operating systems like Unix. Most Unix
    processes do not, in fact, take any CPU time at all when in the
    background.

    Microsoft Word is an obvious exception, it seems to take around 50% of
    CPU in the background. But that's MS for you. I have no idea what the
    hell it's doing with all those cycles, but it's certainly not a
    characteristic of Unix.

    --
    Tom "Tom" Harrington
    Macaroni, Automated System Maintenance for Mac OS X.
    Version 1.4: Best cleanup yet, gets files other tools miss.
    See http://www.atomicbird.com/
    Tom Guest

  8. #8

    Default Re: Running several programs at once

    On 20 Oct 2003 09:54:15 -0700, Jason Carucci <com> wrote:
     

    This doesn't answer your question directly, but bear with me - it is
    relevant. Open up a shell (go -> applications - utilities -> terminal)
    and type:
    top
    Top is a common Unix tool to give you a live view into the system
    and how it's allocating it's resources. (note that "top" is a pretty
    heavy resource hog in itself...). You can see how you're doing with
    memory, CPU, etc. If you read the man page for top:
    man top
    That'll give you descriptions of the default output and the configurable
    options. So, you can open up "top" and have a look while you're moving
    things to the foreground & background. Depending on, well, lots of
    things, the apps may or may not do anything differently just because
    their display is minimized, but this gives you a view into that.

    Hope this helps,
    Dave Hinz

    Dave Guest

  9. #9

    Default Re: Running several programs at once

    In comp.sys.mac.apps Jason Carucci <com> wrote: 

    Yes, as long as you have sufficient spare memory and swap space.
     

    Open up a few large doents in different apps in Mac OS X, then open up
    a terminal window and type "top" to see for yourself what's happening.
    Of course, the more swapping that happens, the more there is a need to
    upgrade to more memory.
    stan@temple.edu Guest

  10. #10

    Default Re: Running several programs at once

    In article <bn1uh9$rpli1$news.uni-berlin.de>,
    Dave Hinz <net> wrote:
     
    >
    > This doesn't answer your question directly, but bear with me - it is
    > relevant. Open up a shell (go -> applications - utilities -> terminal)
    > and type:
    > top
    > Top is a common Unix tool to give you a live view into the system
    > and how it's allocating it's resources. (note that "top" is a pretty
    > heavy resource hog in itself...). You can see how you're doing with
    > memory, CPU, etc. If you read the man page for top:
    > man top
    > That'll give you descriptions of the default output and the configurable
    > options. So, you can open up "top" and have a look while you're moving
    > things to the foreground & background. Depending on, well, lots of
    > things, the apps may or may not do anything differently just because
    > their display is minimized, but this gives you a view into that.[/ref]

    The most immediately useful number in Top is the *M Free bit at the end
    of the line that starts PhysMem. If that gets down to less than, oh, a
    dozen MB, then you know your Mac is loading up virtual memory and will
    be helped with more physical RAM.

    I have a G3/300 that had 128MB. When I ran OS X, it was okay in
    perofrmance, but when I loaded up the OS 9 environment it became
    downright doggy. I added a 256MB stick, expanding memory to 384MB. The
    MB Free number was consistently much higher than just a few MB, and
    performance was a lot better. Then I splurged for three more just so I
    could say I have a GB of RAM. It takes a lot of load up this baby now.
    (Having a GB of RAM is more fun if you remember the days when the
    Osborne One's 64kB of RAM caused people's jaws to drop and made them ask
    what on Earth one would use all that memory for.)

    --
    Woofbert, Chief Rocket Surgeon, Infernosoft
    Woofbert's Law on Learning Linux: When attempting to learn Linux,
    study it thoroughly before you begin.
    Woofbert Guest

  11. #11

    Default Re: Running several programs at once

    Jason Carucci wrote: 

    Yep. Any apps that aren't doing anything will just page out as other
    processes use memory.
     

    Not the case in Mac OS X. If an app doesn't have any events to process,
    it doesn't use any CPU time.
     

    It will use virtual memory, but if its idle it won't be using physical memory.
     

    The only case where having a bunch of apps open and idle will affect you
    on Mac OS X is if you're almost out of disk space and the size of the VM
    storage becomes an issue.
     

    He's correct.

    -jcr
    John Guest

  12. #12

    Default Re: Running several programs at once

    In article <sonic.net>,
    Woofbert <com> wrote:
     

    Not really. Your Mac will try hard to use as much of physical RAM as it
    can, since if it doesn't use it, the memory's just being wasted. My
    PowerBook has about 6 MB "free" right now, but it doesn't need more RAM.

    The best way to tell whether you could use more RAM is if the pageouts
    field in top's output has a large and frequently increasing number next
    to it. A page out occurs when your computer needs memory but doesn't
    have any immediately available, so it has to take a block of memory that
    another application is using but doesn't need right now and write it to
    disk. Writing to disk is slow, so you notice the performance impact of
    a lot of paging. If your computer is paging out often, the applications
    that you're running are using more memory than you have. Adding more
    RAM will cause them the system to page less frequently, which in turn
    will speed things up quite a bit.

    -Eric

    --
    Eric Albert edu
    http://rescomp.stanford.edu/~ejalbert/
    Eric Guest

  13. #13

    Default Re: Running several programs at once

    Tom Harrington wrote: 
    >
    >
    > Others have covered the rest of your post, so I'll just hone in on
    > what's left. I'm guessing that your development experience was not on
    > preemptively multitasking operating systems like Unix. Most Unix
    > processes do not, in fact, take any CPU time at all when in the
    > background.[/ref]

    Ditto with Windows, especially true for Windows NT, Windows 2000 and
    Windows XP.
     

    Is this on Mac or Windows? Please state the OS version you were using.

    What version of Word?

    When did you observe this? Please state the month and year.

    How did you determine the 50% of CPU usage? Please state any and all
    utilities you used.

    Can you reproduce this behavior?

    I have had a Word doent open for 15 minutes on my PC running Office
    2000 under Windows XP and Task Manager shows that WINWORD.EXE has
    consumed 0:00:00 of CPU time. This conflicts with your observations.

    Regards
    --
    Bill

    Bill Guest

  14. #14

    Default Re: Running several programs at once

    In article <nA3lb.4563$news.pas.earthlink.net>,
    Bill Gutz <com> wrote:
     
    > >
    > >
    > > Others have covered the rest of your post, so I'll just hone in on
    > > what's left. I'm guessing that your development experience was not on
    > > preemptively multitasking operating systems like Unix. Most Unix
    > > processes do not, in fact, take any CPU time at all when in the
    > > background.[/ref]
    >
    > Ditto with Windows, especially true for Windows NT, Windows 2000 and
    > Windows XP.[/ref]

    Except not. Most Microsoft apps, at least, seem to override or at least
    cirvent this behavior (which is certainly possible). Word seems to
    constantly repaginate. I haven't got a clue what SourceSafe is doing -
    possibly constantly polling its DB for status changes.

     
    >
    > Is this on Mac or Windows? Please state the OS version you were using.
    >
    > What version of Word?
    >
    > When did you observe this? Please state the month and year.[/ref]

    I don't know about Tom. I can observe it today on OS X and on the
    current Windows version running in Win2k.

     

    Task manager, top, 3rd-party monitoring tools.

     

    Yes. Launch Word.


    Ah. I see. This was cross-posted to an advocacy group.
    Gregory Guest

  15. #15

    Default Re: Running several programs at once

    On Tue, 21 Oct 2003 05:35:15 GMT, Bill Gutz <com> wrote: 
    >
    > Ditto with Windows, especially true for Windows NT, Windows 2000 and
    > Windows XP.[/ref]

    My experience with Win2K differs from your statement.
     
    >
    > Is this on Mac or Windows? Please state the OS version you were using.
    > What version of Word?
    > When did you observe this? Please state the month and year.[/ref]

    Tom says he saw it; for me that's good enough. Why the "Spanish Inquisition"
    tone here?
     

    'Cause, as you know, Noooooobody expects the Spanish Inquisition.
     

    And yet, it matches with mine. No, I don't care to find a Windows box
    to reproduce it on. (checks headers) Ahhhh, an advocacy group post.
    That explains much. Must fix that.





    Dave Guest

  16. #16

    Default Re: Running several programs at once

    In article <google.com>, Jason
    Carucci <com> wrote:
     

    A properly written program will block when it's not doing anything, and
    thus, consume no cycles.
     

    It will still consume memory, but that memory will be swapped to disk
    after it has been inactive.

    Wade
    Wade Guest

  17. #17

    Default Re: Running several programs at once

    In article <nA3lb.4563$news.pas.earthlink.net>,
    Bill Gutz <com> wrote: 
    > >
    > >
    > > Others have covered the rest of your post, so I'll just hone in on
    > > what's left. I'm guessing that your development experience was not on
    > > preemptively multitasking operating systems like Unix. Most Unix
    > > processes do not, in fact, take any CPU time at all when in the
    > > background.[/ref]
    >
    > Ditto with Windows, especially true for Windows NT, Windows 2000 and
    > Windows XP.[/ref]

    OK, whatever, I wouldn't know.
     
    >
    > Is this on Mac or Windows? Please state the OS version you were using.
    >
    > What version of Word?
    >
    > When did you observe this? Please state the month and year.[/ref]

    This was on Mac OS X version 10.2.6, running Word X. I observed this
    yesterday, not long before I posted my previous message. I might not
    have noticed it except that Word kept my PowerBook busy enough that it
    had to run its fan, which it normally doesn't do when idle.
     

    I determined 50% of CPU using "top" at the Mac OS X command line. Since
    you're using Windows you might not be familiar with it, but it's a
    standard Unix tool. In order to minimize the interference of "top" with
    its own results, and in order to sort by CPU usage, I invoked it as:

    top -u -s 5

    I have not observed this behavior with any applications other than MS
    Word. Since my laptop's fan acts as a sort of alarm, something that
    makes me wonder what's going on when it runs unexpectedly, I feel
    confident that I have not missed any examples.
     

    Any time I want to.
     

    What do I care what Windoze XP does? These are Mac newsgroups.

    --
    Tom "Tom" Harrington
    Macaroni, Automated System Maintenance for Mac OS X.
    Version 1.4: Best cleanup yet, gets files other tools miss.
    See http://www.atomicbird.com/
    Tom Guest

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