On 16 August 2011 12:49, mark florisson <markflorisso...@gmail.com> wrote: > On 16 August 2011 11:39, mark florisson <markflorisso...@gmail.com> wrote: >> On 15 August 2011 23:33, Dag Sverre Seljebotn >> <d.s.seljeb...@astro.uio.no> wrote: >>> Would it be horribly expensive to generate a better runtime error, or even >>> initialize the gil on demand? If the gil is not initialized, get the thread >>> ID of the thread calling the callback and check against the thread entering >>> at module initialization time...I don't know whether pythread.h has a cheap >>> way of achieving this. >> >> I'm not sure how expensive PyThread_get_thread_ident(), for pthreads >> it calls pthread_self() is. So it's either such a call for every with >> gil, or initializing the GIL... I'll try to do some tests later today >> and report back. >> >>> -- >>> Sent from my Android phone with K-9 Mail. Please excuse my brevity. >>> >>> Stefan Behnel <stefan...@behnel.de> wrote: >>>> >>>> Dag Sverre Seljebotn, 15.08.2011 11:54: > On 08/15/2011 11:42 AM, mark >>>> florisson wrote: >> @Cython-dev: Do we merely want to update the docs, or >>>> do >>>> we want to >> initialize the GIL for either case, or only for the with gil >>>> >> functions? I'm not entirely sure what the overhead is for >> >>>> single-threaded code, but I'd say we need to initialize it for both >> >>>> cases. > > I'm not sure if I like magic related to having used "with gil" >>>> on >>>> a > function signature -- it's a bit too magic and obscure. I don't really >>>> like this either. The reason why the GIL is not being initialised by >>>> default >>>> is that it has a runtime impact. Just because code is aware of threading >>>> does not mean it is going to be used with threads. Especially library code >>>> (which is a common place for using Cython) shouldn't impose such an impact >>>> on the rest of the runtime. Stefan >>>> ________________________________ >>>> cython-devel mailing list cython-devel@python.org >>>> http://mail.python.org/mailman/listinfo/cython-devel >>> >>> _______________________________________________ >>> cython-devel mailing list >>> cython-devel@python.org >>> http://mail.python.org/mailman/listinfo/cython-devel >>> >>> >> > > Ok, I attached a little script that does some computation > (naive_convolve from the docs). This is the result: > > ➤ python convolve.py > 5.61997413635 > ➤ python convolve.py --with-gil > 5.96432781219 > > So that mean you get approximately a 6% slowdown with the GIL > initialized. The alternative is that we do a check for every with gil > in Cython code for the thread ident + PyEval_ThreadsInitialized() > (haven't tested how much that will slow down with gil blocks, but I > assume the difference would be nearly negligible). > > So I suppose that check + abort would be the way to go? >
Oops, forgot the script.
convolve.py
Description: Binary data
_______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
