[python-win32] Embedded Python and multithreading

[thorsten riesberg]

Hi all,

can anybody explain me why the following code is not running:


// 

#include "stdafx.h"
#include <windows.h> 
#include <strsafe.h> 
#include <stdio.h>
#include "Python.h"




DWORD WINAPI Callback1( LPVOID lpvData){


	PyObject *pName, *pModule, *pDict, *pFunc, *pValue;



	PyThreadState* tcur = PyThreadState_Get() ;

	PyThreadState_Swap(NULL);
	PyThreadState_Clear(tcur);
	PyThreadState_Delete(tcur);

	// release the GIL as PyEval_InitThreads 
	// implicitly acquires the GIL
	PyEval_ReleaseLock();

	PyGILState_STATE gstate;


	for(int i = 0; i < 20; i++){


		gstate = PyGILState_Ensure();

		pName = PyString_FromString("test1");
		pModule = PyImport_Import(pName);


		pDict = PyModule_GetDict(pModule);
		pFunc = PyDict_GetItemString(pDict, "test");

		if (PyCallable_Check(pFunc)) 
		{
			pValue = PyObject_CallObject(pFunc, NULL);
		}
		else {
			PyErr_Print();
		}

		// Clean up

		Py_DECREF(pModule);
		Py_DECREF(pName);

		PyGILState_Release(gstate);
		Sleep(1000);
	}

	return TRUE;
};

DWORD WINAPI Callback2( LPVOID lpvData){



	PyObject *pName, *pModule, *pDict, *pFunc, *pValue;



	PyThreadState* tcur = PyThreadState_Get() ;

	PyThreadState_Swap(NULL);
	PyThreadState_Clear(tcur);
	PyThreadState_Delete(tcur);

	// release the GIL as PyEval_InitThreads 
	// implicitly acquires the GIL
	PyEval_ReleaseLock();

	PyGILState_STATE gstate;


	for(int i = 0; i < 20; i++){

		gstate = PyGILState_Ensure();

		pName = PyString_FromString("test1");
		pModule = PyImport_Import(pName);

		// pDict and pFunc are borrowed references 

		pDict = PyModule_GetDict(pModule);
		pFunc = PyDict_GetItemString(pDict, "test");

		if (PyCallable_Check(pFunc)) 
		{
			pValue = PyObject_CallObject(pFunc, NULL);
		}
		else {
			PyErr_Print();
		}

		// Clean up

		Py_DECREF(pModule);
		Py_DECREF(pName);

		PyGILState_Release(gstate);
		Sleep(1000);
	}

	return TRUE;
};

int main(int argc, char *argv[])
{
	Py_Finalize();
	Py_Initialize();
	PyEval_InitThreads();

	DWORD threadID;
	CreateThread(NULL,10000 ,Callback1,(LPVOID)NULL,0,&threadID);
	CreateThread(NULL,10000 ,Callback2,(LPVOID)NULL,0,&threadID);
	getchar();
	Py_Finalize();
	return 0;
}

If I start just one Thread:

	CreateThread(NULL,10000 ,Callback1,(LPVOID)NULL,0,&threadID);
	//CreateThread(NULL,10000 ,Callback2,(LPVOID)NULL,0,&threadID);

every thing is fine.

The second thread stops with:

Fatal Python error: PyThreadState_Get: no current thread

Thanks in advance
Thorsten
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