Here is one. Others are in the issue report on GitHub.

In Thread 5, the PyObject_SetAttr is where some attribute containing a threading.local object is set to None. This threading.local object had a reference to a sqlite connection object (in some TLS contextes). This should also be the actual crashing thread. I use faulthandler which makes it look like Thread 0 crashed in the crash reporter.

I had this crash about 5% of the time - but totally unpredictable. But it was always happening in exactly that line where the attribute was set to None.


Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib          0x00007fff8a54e0fa __psynch_cvwait + 10
1   libsystem_c.dylib               0x00007fff85daaf89 _pthread_cond_wait + 869
2   org.python.python               0x000000010006f54e PyThread_acquire_lock + 96
3   org.python.python               0x000000010001d8e3 PyEval_RestoreThread + 61
4   org.python.python               0x0000000100075bf3 0x100009000 + 445427
5   org.python.python               0x0000000100020041 PyEval_EvalFrameEx + 7548
6   org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
7   org.python.python               0x0000000100024661 0x100009000 + 112225
8   org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
9   org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
10  org.python.python               0x0000000100024661 0x100009000 + 112225
11  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
12  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
13  org.python.python               0x000000010005df78 0x100009000 + 348024
14  org.python.python               0x000000010001caba PyObject_Call + 97
15  _objc.so                        0x0000000104615898 0x104600000 + 88216
16  libffi.dylib                    0x00007fff8236e8a6 ffi_closure_unix64_inner + 508
17  libffi.dylib                    0x00007fff8236df66 ffi_closure_unix64 + 70
18  com.apple.AppKit                0x00007fff84f63f3f -[NSApplication _docController:shouldTerminate:] + 75
19  com.apple.AppKit                0x00007fff84f63e4e __91-[NSDocumentController(NSInternal) _closeAllDocumentsWithDelegate:shouldTerminateSelector:]_block_invoke_0 + 159
20  com.apple.AppKit                0x00007fff84f63cea -[NSDocumentController(NSInternal) _closeAllDocumentsWithDelegate:shouldTerminateSelector:] + 1557
21  com.apple.AppKit                0x00007fff84f636ae -[NSDocumentController(NSInternal) __closeAllDocumentsWithDelegate:shouldTerminateSelector:] + 265
22  com.apple.AppKit                0x00007fff84f6357f -[NSApplication _shouldTerminate] + 772
23  com.apple.AppKit                0x00007fff84f9134f -[NSApplication(NSAppleEventHandling) _handleAEQuit] + 403
24  com.apple.AppKit                0x00007fff84d40261 -[NSApplication(NSAppleEventHandling) _handleCoreEvent:withReplyEvent:] + 660
25  com.apple.Foundation            0x00007fff867e112b -[NSAppleEventManager dispatchRawAppleEvent:withRawReply:handlerRefCon:] + 308
26  com.apple.Foundation            0x00007fff867e0f8d _NSAppleEventManagerGenericHandler + 106
27  com.apple.AE                    0x00007fff832eeb48 aeDispatchAppleEvent(AEDesc const*, AEDesc*, unsigned int, unsigned char*) + 307
28  com.apple.AE                    0x00007fff832ee9a9 dispatchEventAndSendReply(AEDesc const*, AEDesc*) + 37
29  com.apple.AE                    0x00007fff832ee869 aeProcessAppleEvent + 318
30  com.apple.HIToolbox             0x00007fff8e19f8e9 AEProcessAppleEvent + 100
31  com.apple.AppKit                0x00007fff84d3c916 _DPSNextEvent + 1456
32  com.apple.AppKit                0x00007fff84d3bed2 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 128
33  com.apple.AppKit                0x00007fff84d33283 -[NSApplication run] + 517
34  libffi.dylib                    0x00007fff8236dde4 ffi_call_unix64 + 76
35  libffi.dylib                    0x00007fff8236e619 ffi_call + 853
36  _objc.so                        0x000000010461a663 PyObjCFFI_Caller + 1980
37  _objc.so                        0x000000010462f43e 0x104600000 + 193598
38  org.python.python               0x000000010001caba PyObject_Call + 97
39  org.python.python               0x0000000100020225 PyEval_EvalFrameEx + 8032
40  org.python.python               0x00000001000245eb 0x100009000 + 112107
41  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
42  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
43  org.python.python               0x000000010001dad7 PyEval_EvalCode + 54
44  org.python.python               0x0000000100054933 0x100009000 + 309555
45  org.python.python               0x00000001000549ff PyRun_FileExFlags + 165
46  org.python.python               0x00000001000543e9 PyRun_SimpleFileExFlags + 410
47  albertzeyer.MusicPlayer         0x0000000100001f54 main + 682 (main.m:67)
48  albertzeyer.MusicPlayer         0x0000000100001c6d _start + 203
49  albertzeyer.MusicPlayer         0x0000000100001ba1 start + 33


Thread 1:: Dispatch queue: com.apple.libdispatch-manager
0   libsystem_kernel.dylib          0x00007fff8a54ed16 kevent + 10
1   libdispatch.dylib               0x00007fff88230dea _dispatch_mgr_invoke + 883
2   libdispatch.dylib               0x00007fff882309ee _dispatch_mgr_thread + 54

Thread 2:
0   libsystem_kernel.dylib          0x00007fff8a54e0fa __psynch_cvwait + 10
1   libsystem_c.dylib               0x00007fff85daaf89 _pthread_cond_wait + 869
2   org.python.python               0x000000010006f54e PyThread_acquire_lock + 96
3   org.python.python               0x000000010001d8e3 PyEval_RestoreThread + 61
4   _sqlite3.so                     0x000000010a4041f1 pysqlite_connection_dealloc + 76
5   org.python.python               0x00000001000729f3 0x100009000 + 432627
6   org.python.python               0x00000001000729f3 0x100009000 + 432627
7   org.python.python               0x0000000100052b55 PyThreadState_Clear + 136
8   org.python.python               0x000000010007610a 0x100009000 + 446730
9   libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
10  libsystem_c.dylib               0x00007fff85d93181 thread_start + 13

Thread 3:
0   libsystem_kernel.dylib          0x00007fff8a54e0fa __psynch_cvwait + 10
1   libsystem_c.dylib               0x00007fff85daaf89 _pthread_cond_wait + 869
2   org.python.python               0x000000010006f54e PyThread_acquire_lock + 96
3   org.python.python               0x000000010001d8e3 PyEval_RestoreThread + 61
4   _objc.so                        0x00000001046234a3 0x104600000 + 144547
5   org.python.python               0x00000001000a4194 0x100009000 + 635284
6   org.python.python               0x0000000100021a49 PyEval_EvalFrameEx + 14212
7   org.python.python               0x00000001000245eb 0x100009000 + 112107
8   org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
9   org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
10  org.python.python               0x000000010005df78 0x100009000 + 348024
11  org.python.python               0x000000010001caba PyObject_Call + 97
12  org.python.python               0x000000010001ec59 PyEval_EvalFrameEx + 2452
13  org.python.python               0x00000001000245eb 0x100009000 + 112107
14  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
15  org.python.python               0x00000001000245eb 0x100009000 + 112107
16  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
17  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
18  org.python.python               0x000000010005df78 0x100009000 + 348024
19  org.python.python               0x000000010001caba PyObject_Call + 97
20  org.python.python               0x000000010003719a 0x100009000 + 188826
21  org.python.python               0x000000010001caba PyObject_Call + 97
22  org.python.python               0x0000000100023dfc PyEval_CallObjectWithKeywords + 177
23  org.python.python               0x0000000100076010 0x100009000 + 446480
24  libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
25  libsystem_c.dylib               0x00007fff85d93181 thread_start + 13

Thread 4:
0   libsystem_kernel.dylib          0x00007fff8a54e0fa __psynch_cvwait + 10
1   libsystem_c.dylib               0x00007fff85daaf89 _pthread_cond_wait + 869
2   org.python.python               0x000000010006f54e PyThread_acquire_lock + 96
3   org.python.python               0x000000010001d8e3 PyEval_RestoreThread + 61
4   org.python.python               0x0000000100053351 PyGILState_Ensure + 93
5   _objc.so                        0x0000000104609b6e 0x104600000 + 39790
6   libobjc.A.dylib                 0x00007fff880c6230 (anonymous namespace)::AutoreleasePoolPage::pop(void*) + 464
7   com.apple.CoreFoundation        0x00007fff8ec15342 _CFAutoreleasePoolPop + 34
8   com.apple.Foundation            0x00007fff867e003d -[NSAutoreleasePool release] + 154
9   com.apple.CoreFoundation        0x00007fff8ebed85a CFRelease + 170
10  _objc.so                        0x000000010462349b 0x104600000 + 144539
11  org.python.python               0x00000001000a4194 0x100009000 + 635284
12  org.python.python               0x0000000100021a49 PyEval_EvalFrameEx + 14212
13  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
14  org.python.python               0x0000000100024661 0x100009000 + 112225
15  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
16  org.python.python               0x00000001000245eb 0x100009000 + 112107
17  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
18  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
19  org.python.python               0x000000010005df78 0x100009000 + 348024
20  org.python.python               0x000000010001caba PyObject_Call + 97
21  org.python.python               0x000000010001ec59 PyEval_EvalFrameEx + 2452
22  org.python.python               0x00000001000245eb 0x100009000 + 112107
23  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
24  org.python.python               0x00000001000245eb 0x100009000 + 112107
25  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
26  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
27  org.python.python               0x000000010005df78 0x100009000 + 348024
28  org.python.python               0x000000010001caba PyObject_Call + 97
29  org.python.python               0x000000010003719a 0x100009000 + 188826
30  org.python.python               0x000000010001caba PyObject_Call + 97
31  org.python.python               0x0000000100023dfc PyEval_CallObjectWithKeywords + 177
32  org.python.python               0x0000000100076010 0x100009000 + 446480
33  libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
34  libsystem_c.dylib               0x00007fff85d93181 thread_start + 13

Thread 5:
0   org.python.python               0x000000010007575e 0x100009000 + 444254
1   org.python.python               0x0000000100071cbe 0x100009000 + 429246
2   org.python.python               0x0000000100071bcd PyDict_SetItem + 145
3   org.python.python               0x0000000100079a55 PyObject_GenericSetAttr + 327
4   org.python.python               0x0000000100079538 PyObject_SetAttr + 157
5   org.python.python               0x000000010001f303 PyEval_EvalFrameEx + 4158
6   org.python.python               0x00000001000245eb 0x100009000 + 112107
7   org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
8   org.python.python               0x00000001000245eb 0x100009000 + 112107
9   org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
10  org.python.python               0x00000001000245eb 0x100009000 + 112107
11  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
12  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
13  org.python.python               0x000000010005df78 0x100009000 + 348024
14  org.python.python               0x000000010001caba PyObject_Call + 97
15  org.python.python               0x000000010001ec59 PyEval_EvalFrameEx + 2452
16  org.python.python               0x00000001000245eb 0x100009000 + 112107
17  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
18  org.python.python               0x00000001000245eb 0x100009000 + 112107
19  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
20  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
21  org.python.python               0x000000010005df78 0x100009000 + 348024
22  org.python.python               0x000000010001caba PyObject_Call + 97
23  org.python.python               0x000000010003719a 0x100009000 + 188826
24  org.python.python               0x000000010001caba PyObject_Call + 97
25  org.python.python               0x0000000100023dfc PyEval_CallObjectWithKeywords + 177
26  org.python.python               0x0000000100076010 0x100009000 + 446480
27  libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
28  libsystem_c.dylib               0x00007fff85d93181 thread_start + 13

Thread 6:
0   libsystem_kernel.dylib          0x00007fff8a54e386 __semwait_signal + 10
1   libsystem_c.dylib               0x00007fff85e30800 nanosleep + 163
2   libsystem_c.dylib               0x00007fff85e30717 usleep + 54
3   ffmpeg.so                       0x000000010bd7609d PlayerObject::workerProc(PyMutex&, bool&) + 509 (ffmpeg_player_decoding.cpp:1087)
4   ffmpeg.so                       0x000000010bd78ac2 boost::function2<void, PyMutex&, bool&>::operator()(PyMutex&, bool&) const + 28 (function_template.hpp:759)
5   ffmpeg.so                       0x000000010bd78736 PyThread_thread(void*) + 25 (ffmpeg_utils.cpp:98)
6   libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
7   libsystem_c.dylib               0x00007fff85d93181 thread_start + 13

Thread 7:
0   libsystem_kernel.dylib          0x00007fff8a54e322 __select + 10
1   time.so                         0x00000001007f9d83 0x1007f9000 + 3459
2   org.python.python               0x0000000100020041 PyEval_EvalFrameEx + 7548
3   org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
4   org.python.python               0x000000010005df78 0x100009000 + 348024
5   org.python.python               0x000000010001caba PyObject_Call + 97
6   org.python.python               0x000000010001ec59 PyEval_EvalFrameEx + 2452
7   org.python.python               0x00000001000245eb 0x100009000 + 112107
8   org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
9   org.python.python               0x00000001000245eb 0x100009000 + 112107
10  org.python.python               0x00000001000200d2 PyEval_EvalFrameEx + 7693
11  org.python.python               0x000000010001e281 PyEval_EvalCodeEx + 1956
12  org.python.python               0x000000010005df78 0x100009000 + 348024
13  org.python.python               0x000000010001caba PyObject_Call + 97
14  org.python.python               0x000000010003719a 0x100009000 + 188826
15  org.python.python               0x000000010001caba PyObject_Call + 97
16  org.python.python               0x0000000100023dfc PyEval_CallObjectWithKeywords + 177
17  org.python.python               0x0000000100076010 0x100009000 + 446480
18  libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
19  libsystem_c.dylib               0x00007fff85d93181 thread_start + 13

Thread 8:: com.apple.audio.IOThread.client
0   libsystem_kernel.dylib          0x00007fff8a54c686 mach_msg_trap + 10
1   libsystem_kernel.dylib          0x00007fff8a54bc42 mach_msg + 70
2   com.apple.audio.CoreAudio       0x00007fff825a117a HALB_MachPort::SendMessageWithReply(unsigned int, unsigned int, unsigned int, unsigned int, mach_msg_header_t*, bool, unsigned int) + 98
3   com.apple.audio.CoreAudio       0x00007fff825a1108 HALB_MachPort::SendSimpleMessageWithSimpleReply(unsigned int, unsigned int, int, int&, bool, unsigned int) + 42
4   com.apple.audio.CoreAudio       0x00007fff8259f8db HALC_ProxyIOContext::IOWorkLoop() + 1209
5   com.apple.audio.CoreAudio       0x00007fff8259f391 HALC_ProxyIOContext::IOThreadEntry(void*) + 83
6   com.apple.audio.CoreAudio       0x00007fff8259f24b HALB_IOThread::Entry(void*) + 75
7   libsystem_c.dylib               0x00007fff85da6742 _pthread_start + 327
8   libsystem_c.dylib               0x00007fff85d93181 thread_start + 13