First of all, I apologise if this is not the right topic for this list. Some beta testers of an application I'm working on experience rather strange and sudden crashes, very often when the application is doing nothing, just sitting idle in the background. The crash happens in a thread named "com.apple.root.default-priority" and it's not even controlled by the application. As far as I figure it out, it is triggered by the system to release some memory from caches the application uses. This is the part of the crash report related to that particular thread:
Thread 8 Crashed:: Dispatch queue: com.apple.root.default-priority 0 libsystem_kernel.dylib 0x00007fff8d847ce2 __pthread_kill + 10 1 libsystem_c.dylib 0x00007fff9009e7d2 pthread_kill + 95 2 libsystem_c.dylib 0x00007fff9008fa7a abort + 143 3 libc++abi.dylib 0x00007fff8a1e77bc abort_message + 214 4 libc++abi.dylib 0x00007fff8a1e4fcf default_terminate() + 28 5 libobjc.A.dylib 0x00007fff8a69a1b9 _objc_terminate + 94 6 libc++abi.dylib 0x00007fff8a1e5001 safe_handler_caller(void (*)()) + 11 7 libc++abi.dylib 0x00007fff8a1e505c std::terminate() + 16 8 libc++abi.dylib 0x00007fff8a1e6152 __cxa_throw + 114 9 libobjc.A.dylib 0x00007fff8a699e7a objc_exception_throw + 327 10 com.apple.CoreFoundation 0x00007fff8c8b92a9 -[NSException raise] + 9 11 com.apple.ExceptionHandling 0x0000000100332e0a NSExceptionHandlerUncaughtSignalHandler + 37 12 libsystem_c.dylib 0x00007fff900f0cfa _sigtramp + 26 13 com.apple.CoreFoundation 0x00007fff8c793c0b CFRelease + 27 14 libcache.dylib 0x00007fff8fb4d8e4 _value_entry_remove + 142 15 libcache.dylib 0x00007fff8fb4d9cd _entry_unmap + 81 16 libcache.dylib 0x00007fff8fb4da71 _entry_evict + 153 17 libcache.dylib 0x00007fff8fb4db04 _evict_last + 106 18 libcache.dylib 0x00007fff8fb4dcf2 _cache_enforce_limits + 34 19 libcache.dylib 0x00007fff8fb4dea5 cache_handle_memory_pressure + 125 20 libdispatch.dylib 0x00007fff888bf2b6 _dispatch_source_invoke + 635 21 libdispatch.dylib 0x00007fff888bbf77 _dispatch_queue_invoke + 71 22 libdispatch.dylib 0x00007fff888bb760 _dispatch_worker_thread2 + 198 23 libsystem_c.dylib 0x00007fff9009e3da _pthread_wqthread + 316 24 libsystem_c.dylib 0x00007fff9009fb85 start_wqthread + 13 All those crash reports for the crashing thread look the same. Only a few people experience them, but regularly. For others, it practically impossible to reproduce. I'm using higher level Cocoa NSCache API to cache objects. Cached objects are various image representations and much rarely attributed strings and NSNumber instances. I see the crash happens after CFRelease() call, but I can't figure out why. If I try to do CFRelease(NULL), I get almost the same sequence, similar to: 3 libc++abi.dylib 0x00007fff8a1e77bc abort_message + 214 4 libc++abi.dylib 0x00007fff8a1e4fcf default_terminate() + 28 5 libobjc.A.dylib 0x00007fff8a69a1b9 _objc_terminate + 94 6 libc++abi.dylib 0x00007fff8a1e5001 safe_handler_caller(void (*)()) + 11 7 libc++abi.dylib 0x00007fff8a1e505c std::terminate() + 16 8 libc++abi.dylib 0x00007fff8a1e6152 __cxa_throw + 114 9 libobjc.A.dylib 0x00007fff8a699e7a objc_exception_throw + 327 10 com.apple.CoreFoundation 0x00007fff8c8b92a9 -[NSException raise] + 9 11 com.apple.ExceptionHandling 0x0000000100332e0a NSExceptionHandlerUncaughtSignalHandler + 37 12 libsystem_c.dylib 0x00007fff900f0cfa _sigtramp + 26 But I don't know who and why does (if at all) that NULL pointer release. The documentation for libcache says "Calling cache functions from cache callbacks should be avoided to prevent deadlock." I thought maybe when releasing cached objects libcache calls callback methods to release memory and then image representations are doing some caching on their own, which would effectively be calling cache functions from cache callbacks. But this is just a wild guess, I've no idea what is really going on. So, I'd really appreciate if anyone can help me with this. I've got no idea whether it's a but in the application, or the OS. If necessary, I can send the full crash report and also explain what object are being cached using NSCache. -- Dragan _______________________________________________ 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: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
