is it possible to take the advantage of the cython nogil keyword? #128

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1. mrjbq7 commented on Nov 30, 2016

   

   mrjbq7

   on Nov 30, 2016

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   I'm not sure if the underlying TA-Lib C library is fully reentrant, but it seems like it could work.

   Is this a performance issue you're running into?
2. goldenbull commented on Dec 1, 2016

   

   goldenbull

   on Dec 1, 2016

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   I have a python http server hosting an indicator calculating service, which is using ta-lib. Now many clients are using this service simultaneously. The http service is multi-threaded, so the GIL is the bottleneck.
3. mrjbq7 commented on Dec 23, 2016

   

   mrjbq7

   on Dec 23, 2016

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   So we call the ta-lib C functions with a pointer to memory backing a numpy array. What I'm not sure about, is can that pointer change on you if python runs a GC and you aren't holding the GIL, could your pointer be stale?
4. goldenbull commented on Dec 23, 2016

   

   goldenbull

   on Dec 23, 2016

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   to my limited knowledge from cython doc, it seems to be safe if no python object is referenced during the operation.
5. mrjbq7 commented on Dec 23, 2016

   

   mrjbq7

   on Dec 23, 2016

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   The memory is owned by a python object, does that count? It's not obvious to me what happens with a GC triggered while we have a call into ta-lib with nogil.
6. goldenbull commented on Dec 23, 2016

   

   goldenbull

   on Dec 23, 2016

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   GC may move the python object, but will not move the pointer value in the object.
   Here is an example about nogil and numpy in cython
7. goldenbull

   closed this as completedon Feb 2, 2020