[Python-Dev] Re: Regular expressions

Duncan Grisby duncan-pythondev at grisby.org
Thu Nov 24 16:00:57 CET 2005

On Thursday 24 November, Donovan Baarda wrote:

> I don't know if this will help, but in my experience compiling re's
> often takes longer than matching them... are you sure that it's the
> match and not a compile that is taking a long time? Are you using
> pre-compiled re's or are you dynamically generating strings and using
> them?

It's definitely matching time. The res are all pre-compiled.

> > A quick look at the code in _sre.c suggests that for most of the time,
> > no Python objects are being manipulated, so the interpreter lock could
> > be released. Has anyone tried to do that?
> probably not... not many people would have several-minutes-to-match
> re's.
> I suspect it would be do-able... I suggest you put together a patch and
> submit it on SF...

The thing that scares me about doing that is that there might be
single-threadedness assumptions in the code that I don't spot. It's the
kind of thing where a patch could appear to work fine, but them
mysteriously fail due to some occasional race condition. Does anyone
know if there is there any global state in _sre that would prevent it
being re-entered, or know for certain that there isn't?



 -- Duncan Grisby         --
  -- duncan at grisby.org     --
   -- http://www.grisby.org --

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