[Python-ideas] solving multi-core Python
ericsnowcurrently at gmail.com
Thu Jun 25 00:19:27 CEST 2015
On Wed, Jun 24, 2015 at 9:26 AM, Sturla Molden <sturla.molden at gmail.com> wrote:
> On 24/06/15 07:01, Eric Snow wrote:
> There are two major competing standards for parallel computing in science
> and engineering: OpenMP and MPI. OpenMP is based on a shared memory model.
> MPI is based on a distributed memory model and use message passing (hence
> its name).
Thanks for the great explanation!
>> Solving reference counts in this situation is a separate issue that
>> will likely need to be resolved, regardless of which machinery we use
>> to isolate task execution.
> As long as we have a GIL, and we need the GIL to update a reference count,
> it does not hurt so much as it otherwise would. The GIL hides most of the
> scalability impact by serializing flow of execution.
It does hurt in COW situations, e.g. forking. My expectation is that
we'll at least need to take a serious look into the matter in the
short term (i.e. Python 3.6).
>> IPC sounds great, but how well does it interact with Python's memory
>> management/allocator? I haven't looked closely but I expect that
>> multiprocessing does not use IPC anywhere.
> multiprocessing does use IPC. Otherwise the processes could not communicate.
> One example is multiprocessing.Queue, which uses a pipe and a semaphore.
Right. I don't know quite what I was thinking. :)
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