Callback from c thread with ctypes

Victor Lin Bornstub at
Sun Mar 8 14:28:23 CET 2009


I am going to develop a c library binding with ctypes. That c library
will call callback from worker threads it created. Here comes the
problem : Will the GIL be acquired before it goes into Python

I got a little try..

DSPPROC = WINFUNCTYPE(None, DWORD, DWORD, c_void_p, DWORD, c_void_p)

def test(handle, channel, buffer, length, user):
    print handle, channel, buffer, length, user

dsp = BASS_ChannelSetDSP(stream, DSPPROC(test), None, 123)

I got "access violation" when I run it... It seems that the ctypes
did't acquire GIL before it call the python callback. As the document

WINFUNCTYPE will release GIL during the call

But it does not mention callback about Python function? How about a
call from another thread? Could somebody help me?

Victor Lin.

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