[Numpy-discussion] Handling interrupts in NumPy extensions

[Travis Oliphant]

David Cournapeau wrote:
>>>     
>>>       
>> If nothing is known about memory allocation of the external library, 
>> then I don't see how it can be safely interrupted using any mechanism.
>>   
>>     
> If the library does nothing w.r.t signals, then you just have to clean 
> all the things related to the library once
> you caught a signal. This is no different than cleaning your own code. 
>   

Right, as long as you know what to do you are O.K.  I was just thinking 
about a hypothetical situation where the library allocated some 
temporary memory that it was going to free at the end of the subroutine 
but then an interrupt jumped out back to your code before it could 
finish.   In a case like this, you would have to use the "check if 
interrupt has occurred" approach before and after the library call. 

But, then that library call is not interruptable.  I could also see 
wanting to be able to interrupt a library calculation when you know it 
isn't allocating memory.   So, I like having both possibilities available.

So far we haven't actually put anything in the numpy code itself.   I'm 
leaning to putting PyOS_InterruptOccurred-style checks in a few places 
at some point down the road.

-Travis