> > > On Thu, Jan 15, 2009 at 1:59 AM, Bill Bumgarner <b...@mac.com> wrote: > >> > >> For example, an application's VSIZE might be growing over time > >> because it is > >> mmap()'ing a bunch of files (or a few small files). If the app > >> fails to > >> unmap, the VSIZE will grow and the app may likely exhaust its > >> address space > >> without any paging activity. > >> > >> Example: for applications that are processing large files -- ID3 > >> tag editors > >> come to mind -- watching the VSIZE can be a useful way of > >> determining if > >> your code is properly managing the mapping of said files. > > > > All good points. However what I meant by "system resources" was that > > VSIZE, while it may indicate misbehavior in your process, never > > indicates misbehavior that could affect the system as a whole. An app > > with a runaway RSIZE can quickly run you into swap hell. An app with > > runaway CPU usage can make everything else slow. But VSIZE is at most > > an internal problem. That's all I meant to indicate. > > The kernel still needs to keep track of those VSIZE allocations. > Perhaps in 64-bit if you mmap() a small file a few billion times then > the kernel will exhaust some resource or clobber some algorithm's > performance. (Also I bet `top` will be really slow.) > > But yes, in general VSIZE either is not a problem or is only a local > problem. >
I am grateful to everyone who has responded, and, as I expected, many concur that VSIZE is a (largely) meaningless statistic. However, I am still not entirely satisfied with the answer to my first question, which is: How does the OS determine what to allocate for the VSIZE. One answer suggested that 64-bit apps will receive 8GB, but I note that the Apache daemon (httpd) runs in 64-bit mode and is allocated on a few tens-of-megabytes (around 25MB per instance on my machine). Is that because it does not have a GUI and is not written in Obj-C? If the outsized VSIZE does indicate "misbehavior in [my] process", what are the types of things I should look for? I don't have any memory leaks (that I can see -- the app runs for hours without increasing its memory consumption, and nothing obvious appears in instruments). I am not creating hundreds of objects, and I have a limited number of classes in my app. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
