Re: Memory usage
Re: Memory usage
- Subject: Re: Memory usage
- From: Gregory John Casamento <email@hidden>
- Date: Thu, 24 Mar 2005 18:32:50 -0800 (PST)
- Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys
--- Matt Neuburg <email@hidden> wrote:
> On Fri, 25 Mar 2005 00:39:37 +0100, Michael Becker <email@hidden>
> said:
> >Hi!
> >
> >I am not sure if this is the appropriate list to post this, but I am
> >sure people here can answer my question. I have an application that
> >reads out and displays the iPhoto library. After selecting one of the
> >albums, the images of this album are read from disk and displayed. So
> >far, everything works fine, but I just checked my memory usage with the
> >command-line tool "top".
> >
> >I must admit that I am in no ways a memory expert, so there may be
> >wrong assumptions here. What worries me the most is, that unlike
> >iPhoto, my app's stats grow worse over time. That means, if I change
> >between the albums, each of the numbers in top grows. Although I am
> >properly releasing my objects, it seems as memory usage increases.
> >
> >In my list, every running app uses at most about 400 REGS (memory
> >regions). But my app (after some album switching) easily reaches more
> >than 1500 of those.
> >
> >Now here is the question: Why does my app increase in memory usage even
> >though I properly facilitate Cocoa's memory management? Say, I have 100
> >images in the current album view. When I switch the album, those 100
> >images are released, then the new album's images are read from disk. If
> >the new album only has 10 images, shouldn't that drop my mem-usage?
> >
> >I'm sorry if I am asking stupid questions, but as I mentioned before, I
> >am new to this stuff and a little scared of the moment when a user uses
> >my app for more than 30 minutes :-)
>
> First of all, don't do memory management with any other tool than e.g.
> ObjectAlloc. Mac OS X virtual memory will mislead you, because it retains
> memory you are not actually using, so think only in terms of actual objects
> / leaks. That said, virtual memory itself can take a little management. The
> problem might be that virtual memory doesn't let go of disk areas that you
> read. This is very noticeable with big disk areas (i.e. images). I had this
> problem with an image-processing app until Michael Rothwell put me onto
> fcntl and F_NOCACHE. This solved things instantly. Check the archives. m.
>
> PS Also memory management with images is tricky in general because of
> caching. I do a lot of recaching (perhaps unnecessarily).
>
> --
> matt neuburg, phd = email@hidden, <http://www.tidbits.com/matt/>
> A fool + a tool + an autorelease pool = cool!
> AppleScript: the Definitive Guide
> <http://www.amazon.com/exec/obidos/ASIN/0596005571/somethingsbymatt>
>
>
>
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Gregory John Casamento
-- CEO/President Open Logic Corp. (A MD Corp.)
## Maintainer of Gorm (IB Equiv.) for GNUstep.
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