Python Threads and C Semaphores

[Jeremy]

Hello,

I have a fat C++ extension to a Python 2.3.4 program. In all, I count
five threads. Of these, two are started in Python using
thread.start_new_thread(), and both of these wait on semaphores in the C++
extension using sem_wait(). There also are two other Python threads and one
thread running wholly in
the extension.

I notice that when one of the Python threads calls the extension and waits
on a semaphore, all but the C++ thread halt even when not waiting on any
semaphore. How do we get this working right?

Thank you,
Jeremy

 

[Dejan Rodiger]

Jeremy said the following on 16.1.2007 8:27:

Hello,

I have a fat C++ extension to a Python 2.3.4 program. In all, I count
five threads. Of these, two are started in Python using
thread.start_new_thread(), and both of these wait on semaphores in the C++
extension using sem_wait(). There also are two other Python threads and one
thread running wholly in
the extension.

I notice that when one of the Python threads calls the extension and waits
on a semaphore, all but the C++ thread halt even when not waiting on any
semaphore. How do we get this working right?

Check the Global Interpreter Lock

 

[Andrew MacIntyre]

Jeremy said the following on 16.1.2007 8:27:


Check the Global Interpreter Lock

More specifically, make sure that any extension code that does not
call Python API functions releases the GIL for the duration.

Look into the Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS macros and the
PyGILState*() API functions (these API functions appeared in Python 2.3).

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