[Python-Dev] PyThreadState_GET() returns NULL from within PyImport_GetModuleDict() (original) (raw)

Patrick Rutkowski patrick.rutkowski at gmail.com
Mon Aug 7 20:11:13 EDT 2017

I'm working on Windows. I have the following dead simple embedding code that I'm using to test out the python interpreter:

============================================================

Py_SetProgramName(L"MyApp");

Py_SetPath( L"C:\Users\rutski\Documents\python\PCBuild\amd64\python36.zip;" L"C:\Users\rutski\Documents\python\DLLs;" L"C:\Users\rutski\Documents\python\lib;" L"C:\Users\rutski\Documents\python\PCBuild\amd64;" L"C:\Users\rutski\Documents\python;" L"C:\Users\rutski\Documents\python\lib\site-packages");

Py_Initialize();

PyRun_SimpleString( "from time import time,ctime\n" "print('Today is', ctime(time()))\n");

============================================================

This code crashes trying to access address 0x00000010 from within PyRun_SimpleString(). The sequence of event's is this:

  1. PyRun_SimpleString() tries to do AddModule("main")
  2. AddModule tries to do PyImport_GetModuleDict()
  3. PyImport_GetModuleDict() tries to doPyThreadState_GET()->interp
  4. PyThreadState_GET() returns NULL, so the ->interp part crashes.

The weird thing is that calling PyImport_GetModuleDict() from within my application directly works just fine. Weirder still is that the whole thing actually executes fine if I build a windows command line application with the embed code in main(), and execute it from a terminal. The crash only happens when building a Windows GUI application and calling the embed code in WinMain().

This is a python interpreter that I built from source on windows using PCbuild\build.bat, so that I could track the crash. However, the exact same crash was happening with the stock interpreter provided by the python windows installer.

Does anyone have any ideas here? -Patrick

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