Threaded GUI slowing method execution?

Ole Streicher ole-usenet-spam at
Fri Oct 2 20:19:35 CEST 2009

sturlamolden <sturlamolden at> writes:
> On 2 Okt, 13:29, Dave Angel <da... at> wrote:
> If you are worried about speed, chances are you are not using Python
> anyway.

I *do* worry about speed. And I use Python. Why not? There are powerful
libraries available.

> If you still have "need for speed" on a multicore, you can use Cython
> and release the GIL when appropriate. Then launch multiple Python
> threads and be happy.

Usually this is not an option: numpy is AFAIK not available for Cython,
neither is scipy (ofcourse).

Especially for numeric calculations, speed *matters*.

> Using more than one process is always an option, i.e. os.fork if you
> have it or multiprocessing if you don't. Processes don't share GIL.

Not if the threads/processes need to share lots of data. Interprocess
communication can be very expensive -- even more if one needs to share
Python objects. Also, the support of sharing python objects between
processes seems to me not well supported at least by the standard python


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