[Python-bugs-list] [ python-Bugs-489672 ] memory leak in test_sre
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Thu, 06 Dec 2001 20:13:54 -0800
Bugs item #489672, was opened at 2001-12-05 18:45
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Category: Regular Expressions
Group: Python 2.2
Status: Open
Resolution: None
Priority: 7
Submitted By: Neal Norwitz (nnorwitz)
Assigned to: Guido van Rossum (gvanrossum)
Summary: memory leak in test_sre
Initial Comment:
leak when running test_sre
see attached file for details
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>Comment By: Tim Peters (tim_one)
Date: 2001-12-06 20:13
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Heh -- I have the same fix and already have confidence. I
was just about to check it in, but will wait to make sure
you don't first.
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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-06 20:09
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I think I've found this. There's a missing Py_DECREF(filter)
in pattern_subx() in _sre.c. I'll check it in once I've got
more confidence in the fix.
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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-06 19:44
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>From email. That was it. With two backslashes it leaks like
a sieve.
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Comment By: Tim Peters (tim_one)
Date: 2001-12-06 19:04
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Guido, did you take the snippet from email or from the web
page? It doesn't "look right" in email (for a change!).
The 2nd argument to re.sub must have two backslashes; one
of them vanishes in the email version ... I'll try
attaching it as a file.
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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-06 18:56
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Hm. For me (on Linux) that snippet doesn't leak at all. Are
you sure this is it?
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Comment By: Tim Peters (tim_one)
Date: 2001-12-06 18:35
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This derived snippet leaks at a prodigious rate:
import re
while 1: re.sub('(a)', '\1', 'a')
Variations don't leak if the capturing group is removed
from the regexp, or if the replacement text doesn't
reference the group.
I'm reassigning to /F based on that evidence (it appears to
have to do with re.sub internals, not with a general Python
screwup).
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Comment By: Tim Peters (tim_one)
Date: 2001-12-06 15:18
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Hard? Unpleasant? Mine <wink>! Reassigned to me, cuz in
a moment of weakness I said I would.
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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-12-06 14:08
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It's hard to make progress on this. In a loop it doesn't
leak or leaks too slowly to be useful. The code is not in a
function so it's hard to whittle down effectively.
The first leak reported by Purify is a string literal (or
actially, 4 string literals); this isn't much of a hint
since the code is chock full of those.
The second leak reported is also a string, but one created
through concatenation. There aren't too many of those in
test_sre.py, but still, who knows which one it is...
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