using python interpreters per thread in C++ program

[Mark Hammond]

On 8/09/2009 9:16 AM, Grant Edwards wrote:
> On 2009-09-07, Mark Hammond<skippy.hammond at gmail.com>  wrote:
>
>>> CPython's GIL means that multithreading on multiple
>>> processors/cores has limitations. Each interpreter has its own
>>> GIL, so processor-intensive applications work better using the
>>> multiprocessing module than with the threading module.
>>
>> I believe you will find the above is incorrect - even with
>> multiple interpreter states you still have a single GIL.
>
> Please explain how multiple processes, each with a separate
> Python interpreter, share a single GIL.


Sorry, my mistake, I misread the original - using multiple Python 
processes does indeed have a GIL per process.  I was referring to the 
'multiple interpreters in one process' feature of Python which is 
largely deprecated, but if used, all 'interpreters' share the same GIL.

To clarify: in a single process there will only ever be one GIL, but in 
multiple processes there most certainly will be multiple GILs.

Apologies for the confusion...

Cheers,

Mark