[Python-Dev] New regex module for 3.2?

[Georg Brandl]

Am 22.07.2010 14:12, schrieb Nick Coghlan:
> On Thu, Jul 22, 2010 at 9:34 PM, Georg Brandl <g.brandl at gmx.net> wrote:
>> So, I thought there wasn't a difference in performance for this use case
>> (which is compiling a lot of regexes and matching most of them only a
>> few times in comparison).  However, I found that looking at the regex
>> caching is very important in this case: re._MAXCACHE is by default set to
>> 100, and regex._MAXCACHE to 1024.  When I set re._MAXCACHE to 1024 before
>> running the test suite, I get times around 18 (!) seconds for re.
> 
> That still fits with the compile/match performance trade-off changes
> between re and regex though. It does make it clear this isn't going to
> be a win across the board though - things like test suites are going
> to have more one-off regex operations than a long-running web server
> or a filesystem or database scanning operation.

Sure -- I don't think this is a showstopper for regex.  However if we don't
include regex in a future version, we might think about increasing MAXCACHE
a bit, and maybe not clear the cache when it reaches its max length, but
rather remove another element.

Georg

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