Re: crashes loading saved file
Re: crashes loading saved file
- Subject: Re: crashes loading saved file
- From: Nick Zitzmann <email@hidden>
- Date: Wed, 09 May 2012 13:59:13 -0600
On May 9, 2012, at 12:58 PM, James Maxwell wrote:
> I've been having problems with my app crashing with an EXC_BAD_ACCESS while unarchiving a saved data file. The file is a graph representation of musical structure, created by a machine learning algorithm. When the file/graph is small there are no problems, but as I add more training material, and the file increases in size, at a certain point it starts crashing during unarchiving.
Are you building for OS X or iOS? If the former, then are you building for X86 or X86-64? If the former, then have you considered transitioning? :)
> This morning, I tried enabling Guard Malloc (on its own, without zombies), and was surprised to see the app crash during training, with the following error:
>
> GuardMalloc[ManuScore-2438]: Failed to VM allocate 1864016 bytes
> GuardMalloc[ManuScore-2438]: Explicitly trapping into debugger!!!
>
>
> Is it simply running out of VM while trying to build the graph?
Yes.
> If so, why doesn't this happen with Guard Malloc off?
Turning Guard Malloc on greatly increases the overall memory usage of the process.
> Also, with zombies and guard malloc off, why is it only when reading the file that the app crashes, not during training (i.e., while the graph is being built)?
You can see for yourself by running your app in Instruments using the object allocations instrument. This is just a guess, but what might be happening is the reading process is directly or indirectly generating many temporary objects that are being pushed into the autorelease/collection pool, which is bulging after a while. If you're using RR or ARC memory management, then you can fix this by grouping code that generates temporary objects into @autoreleasepool blocks. If you're using GC memory management, then you might need to manually run the collector more often.
Nick Zitzmann
<http://www.chronosnet.com/>
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