John Machin wrote:

Hi Matthew,

Your post in c.l.py about your re rewrite didn't mention where to report bugs etc so I dug this address out of Google Groups ...

Environment: Python 2.6.2, Windows XP SP3, your latest (29 July) regex from the Python bugtracker.

Problem is repeated calls of e.g. compiled_pattern.search(some_text) -- Task Manager performance panel shows increasing memory usage with regex but not with re. It appears to be cumulative i.e. changing to another pattern or text doesn't release memory.

Example:

8<-- regex_timer.py import sys import time if sys.platform == 'win32': timer = time.clock else: timer = time.time module = __import__(sys.argv[1]) count = int(sys.argv[2]) pattern = sys.argv[3] expected = sys.argv[4] text = 80 * '~' + 'qwerty' rx = module.compile(pattern) t0 = timer() for i in xrange(count): assert rx.search(text).group(0) == expected t1 = timer() print "%d iterations in %.6f seconds" % (count, t1 - t0) 8<---

Here are the results of running this (plus observed difference between peak memory usage and base memory usage):

dos-prompt>\python26\python regex_timer.py regex 1000000 "~" "~" 1000000 iterations in 3.811500 seconds [60 Mb]

dos-prompt>\python26\python regex_timer.py regex 2000000 "~" "~" 2000000 iterations in 7.581335 seconds [128 Mb]

dos-prompt>\python26\python regex_timer.py re 2000000 "~" "~" 2000000 iterations in 2.549738 seconds [3 Mb]

This happens on a variety of patterns: "w", "wert", "[a-z]+", "[a-z]+t", ...

Thanks for that, John. I've should've kept an eye on the Task Manager! :-) Now fixed. It's surprising how much time and effort is needed just to manage the memory!