NSAutoReleasePool appears not be working

I am writing an iPhone app that starts taking up memory as soon as it starts and just keeps taking up more memory. The reason appears to be that I've included a tight inner loop in that I'd lik开发者_开发百科e to run for a long while. Dont' worry, it's not supposed to be part of the user interactive app, it's just for testing the internal code.

In any case, by searching stackoverflow I found out that I should use my own NSAutoReleasePool because the main one is not getting reached. Also, I found that I should eschew use of autorelease. I've done both of these things, although I haven't been able to get rid of all autorelease calls. These do not fix the problem, however. Now my number of allocations (as per the instruments Allocations tool) travels in a triangle wave pattern, presumably because of the pool draining, but the number of allocations and the overall bytes creeps ever upwards. This increase in memory usage is also reflected in activity monitor. The objects that are getting allocated fall under all sorts of types including Malloc, CFString, NSConcreteMutableData; basically many core library classes and many of my code's objects.

This is basically what I'm doing:

for (int i=0; i<1000; i++) {
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    ... do lots of stuff

    [pool drain];
}

Any ideas why this is happening? I don't have any memory leaks according to the Leaks instrument and I don't have NSZombieEnabled set or any other arguments for that matter.

Thanks

UPDATE: I just noticed some memory leaks are getting found when I use the auto release pool that aren't there when I'm not use the pool. Strange... Maybe that helps point towards the problem. I'm trying to track those leaks down now but so far they don't look like leaks in my code, but they make sense if the pool isn't actually releasing them.

UPDATE: Ok, figured it out and it was caused by a few things. First, I was not properly releasing objects that contained references to each other so these never ended up getting released. Second, there are still memory leaks but these are in the foundation classes. I found an answer somewhere suggesting that this was not surprising, especially when running in the Simulator so I'm not going to worry about it too much. Hopefully this is useful to someone.

This can be caused by certain system caching, i.e. ImageNamed and certain URL calls will actually be cached by the system and are therefore not leaks but also nothing that you can release manually. There are normally better ways to handle such things for example creating your own image caching which you can clear...