This is an example of something that should work but seems to crash python on Mac OS X.

The file multiwx.py contains a simple function that starts a multiprocessing.Process and establishes a multiprocessing.Queue to talk to it. The process then creates a simple wxPython app consisting of a frame with a button. The button puts items onto the Queue. The main process consumes the items until it sees the item None, at which it joins the child process and exits. The item None is sent by the wxPython application when the frame is closed.

The expected behavior is that every button presses causes 'Button!' to be printed by the main process and the frame close event causes 'closing!' and 'done!' to be printed and the program to exit.

On Ubuntu Linux 10.4 Lucid Lynx (x86_64) with Python 2.6.5 and wx.version 2.8.10.1, script behaves as expected.

On Windows 7 with Python 2.7.2 and wxPython 2.8.12.1, script behaves as expected.

On Mac OS X 10.6.8 (x86 Intel), the following crash is produced:

Process: Python [408] Path: /System/Library/Frameworks/Python.framework/Versions/2.6/Resources/Python.app/Contents/MacOS/Python Identifier: Python Version: ??? (???) Code Type: X86 (Native) Parent Process: Python [405]

Date/Time: 2011-09-22 15:15:10.459 -0500 OS Version: Mac OS X 10.6.8 (10K549) Report Version: 6

Interval Since Last Report: 200152 sec Crashes Since Last Report: 11 Per-App Crashes Since Last Report: 5 Anonymous UUID: EE52D522-D315-4B44-90E2-6E4E431A94DD

Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x00000000b011aff0 Crashed Thread: 0 Dispatch queue: com.apple.main-thread

Application Specific Information: multi-threaded process forked

Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.apple.CoreGraphics 0x958671b5 _CG_spin_lock_try + 9 1 com.apple.CoreGraphics 0x95866fd9 CGSShmemRWLockLockForReading + 79 2 com.apple.CoreGraphics 0x95866f81 lockDisplay + 45 3 com.apple.CoreGraphics 0x958786e9 CGSMainDisplayID + 122 4 core.so 0x005a20ec wxPyTestDisplayAvailable() + 12 5 core.so 0x005ac3d1 wxFindWindowByLabel(wxString const&, wxWindow const*) + 1061 6 org.python.python 0x0000c6e0 PyObject_Call + 101 7 org.python.python 0x0008c843 PyEval_EvalFrameEx + 21688 8 org.python.python 0x0008cf74 PyEval_EvalCodeEx + 1720 9 org.python.python 0x0008b5a1 PyEval_EvalFrameEx + 16918 10 org.python.python 0x0008cf74 PyEval_EvalCodeEx + 1720 11 org.python.python 0x0002ee0c PyClassMethod_New + 1823 12 org.python.python 0x0000c6e0 PyObject_Call + 101 13 org.python.python 0x0001c10d PyClass_New + 1603 14 org.python.python 0x0000c6e0 PyObject_Call + 101 15 org.python.python 0x00053d8a _PyType_Lookup + 5617 16 org.python.python 0x00055bc1 PyType_GenericAlloc + 3133 17 org.python.python 0x0000c6e0 PyObject_Call + 101 18 org.python.python 0x0008c812 PyEval_EvalFrameEx + 21639 19 org.python.python 0x0008cf74 PyEval_EvalCodeEx + 1720 20 org.python.python 0x0002ed9f PyClassMethod_New + 1714 21 org.python.python 0x0000c6e0 PyObject_Call + 101 22 org.python.python 0x0008c843 PyEval_EvalFrameEx + 21688 23 org.python.python 0x0008b4e5 PyEval_EvalFrameEx + 16730 24 org.python.python 0x0008b4e5 PyEval_EvalFrameEx + 16730 25 org.python.python 0x0008cf74 PyEval_EvalCodeEx + 1720 26 org.python.python 0x0002ee0c PyClassMethod_New + 1823 27 org.python.python 0x0000c6e0 PyObject_Call + 101 28 org.python.python 0x0001c10d PyClass_New + 1603 29 org.python.python 0x0000c6e0 PyObject_Call + 101 30 org.python.python 0x00053d8a _PyType_Lookup + 5617 31 org.python.python 0x00055bc1 PyType_GenericAlloc + 3133 32 org.python.python 0x0000c6e0 PyObject_Call + 101 33 org.python.python 0x0008c812 PyEval_EvalFrameEx + 21639 34 org.python.python 0x0008b4e5 PyEval_EvalFrameEx + 16730 35 org.python.python 0x0008b4e5 PyEval_EvalFrameEx + 16730 36 org.python.python 0x0008cf74 PyEval_EvalCodeEx + 1720 37 org.python.python 0x0008d019 PyEval_EvalCode + 87 38 org.python.python 0x000a40af Py_CompileString + 111 39 org.python.python 0x000a415b PyRun_FileExFlags + 139 40 org.python.python 0x000a5e7e PyRun_SimpleFileExFlags + 814 41 org.python.python 0x000b315c Py_Main + 3074 42 org.python.python.app 0x00001eb5 start + 53