[concurrency] Inside the Python GIL

John Szakmeister john at szakmeister.net
Sat Jun 13 13:30:45 CEST 2009


On Fri, Jun 12, 2009 at 1:27 PM, David Beazley<dave at dabeaz.com> wrote:
[snip]
> I agree.   I'd even so far as to say that more people should probably go
> pick up an operating systems text and look at it.  In the big picture, the
> GIL doesn't really matter if everything stays I/O bound.   It's only when
> programs start to drift away from I/O processing that things start to get
> fuzzy.   Obviously, the material I presented in the talk is at the opposite
> extreme (where there is heavy CPU processing).   The real question is what
> is happening for programs that sit somewhere in the middle of that space.
> I honestly don't know.

FWIW, I just patched my py3k branch to use native Mach semaphores
instead of the mutex/condition variable combo, and it had a fairly
substantial savings in terms of system calls.  I'll see if I can get
that into some form that's acceptable for inclusion into the core.  It
obviously doesn't fix the greater problem, but at least makes things
more well behaved on Mac.

-John


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