New submission from M. Schmitzer:
The way the fnmatch module uses its regex cache is not threadsafe. When
multiple threads use the module in parallel, a race condition between
retrieving a - presumed present - item from the cache and clearing the cache
(because the maximum size has been reached) can lead to KeyError being raised.
The attached script demonstrates the problem. Running it will (eventually)
yield errors like the following.
Exception in thread Thread-10:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "fnmatch_thread.py", line 12, in run
fnmatch.fnmatchcase(name, pat)
File "/home/marc/.venv/modern/lib/python2.7/fnmatch.py", line 79, in
fnmatchcase
return _cache[pat].match(name) is not None
KeyError: 'lYwrOCJtLU'
--
components: Library (Lib)
files: fnmatch_thread.py
messages: 233650
nosy: mschmitzer
priority: normal
severity: normal
status: open
title: fnmatch regex cache use is not threadsafe
type: crash
versions: Python 2.7
Added file: http://bugs.python.org/file37642/fnmatch_thread.py
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