Adrien Bruneton <adrien.brune...@cea.fr> writes:
> I am having a hard time understanding what is the proper use of
> PyGILState_Ensure/Release.
> My understanding is that one should always be matched with the other,
> and that this high level API auto-magically deals with the ThreadState
> creation.
>
> However the following piece of code (executed with a simple "print
> 'hello world' " script as argv) triggers the message:
>
> Fatal Python error: auto-releasing thread-state, but no
> thread-state for this thread
Each function at the Python C interface has (with high probability)
a notion whether it is called from Python (GIL acquired) or from pure C code
(GIL not acquired). When you call the function yourself, you must match
this expectation. "Py_Main" likely expects to be called without
acquired GIL. Thus, likely, you should not call "PyGILState_Ensure"
before "Py_Main".
> Minimal code:
>
> void initPython(int initsigs)
> {
> if (Py_IsInitialized() == 0)
> {
> Py_InitializeEx(initsigs);
> // Put default SIGINT handler back after
> Py_Initialize/Py_InitializeEx.
> signal(SIGINT, SIG_DFL);
> }
>
> int threadInit = PyEval_ThreadsInitialized();
> PyEval_InitThreads(); // safe to call this multiple time
>
> if(!threadInit)
> PyEval_SaveThread(); // release GIL
> }
>
> int main(int argc, char ** argv)
> {
> initPython(1);
> PyGILState_STATE _gstate_avoid_clash = PyGILState_Ensure();
> int ret = Py_Main(argc, argv);
> PyGILState_Release(_gstate_avoid_clash); // this one triggers the
> Fatal error
> Py_Finalize();
> return ret;
> }
>
>
> Removing the last PyGILState_Release works, but I have a bad feeling
> about it :-)
> Any help would be welcome! Thanks in advance.
Likely, "Py_Main" has already released the GIL and cleaned up
the thread state.
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