[Cython] [cython-users] What's up with PyEval_InitThreads() in python 2.7?

Stefan Behnel stefan_ml at behnel.de
Tue Feb 28 11:53:19 CET 2012

mark florisson, 28.02.2012 11:28:
> On 28 February 2012 10:25, Stefan Behnel wrote:
>> mark florisson, 28.02.2012 11:16:
>>> On 28 February 2012 09:54, Stefan Behnel wrote:
>>>> I'm going to reimplement this, but not for 0.16 anymore, I'd say.
>>> That's ok, I fixed it to not acquire the GIL seeing that control flow
>>> obsoletes None initialization. So you might as well move it into the
>>> setup function if you care, the thing is that that would needlessly
>>> acquire the GIL for the common case (when you have the GIL) in the
>>> tests, so it might slow them down. It would be better to create a
>>> __Pyx_RefNannySetupContextNogil() function wrapper. If you're not
>>> running the code as a test the preprocessor would filter out this
>>> bloat though, so it's really not a very big deal anyway.
>> I was going to pass a constant flag into the macro that would let the C
>> compiler do the right thing:
>> """
>> #ifdef WITH_THREAD
>>  #define __Pyx_RefNannySetupContext(name, acquire_gil) \
>>          if (acquire_gil) { \
>>              PyGILState_STATE __pyx_gilstate_save = PyGILState_Ensure(); \
>>              __pyx_refnanny = __Pyx_RefNanny->SetupContext((name), ...) \
>>              PyGILState_Release(__pyx_gilstate_save); \
>>          } else { \
>>              __pyx_refnanny = __Pyx_RefNanny->SetupContext((name), ...) \
>>          }
>> #else
>>  #define __Pyx_RefNannySetupContext(name, acquire_gil) \
>>          __pyx_refnanny = __Pyx_RefNanny->SetupContext((name), ...)
>> #endif
>> """
>> That also gets rid of the need to declare the "save" variable independently.
> I don't think that will work, I think the teardown re-uses the save variable.

Well, it doesn't *have* to be the same variable, though.

Speaking of that, BTW, there are a couple of places in the code (Nodes.py,
from line 1500 on) that release the GIL, and some of them, specifically
some error cases, look like they are using the wrong conditions to decide
what they need to do in order to achieve that. I think this is most easily
fixed by using the above kind of macro also for the refnanny cleanup call.


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