New submission from Michael Allen:
Modifying a file while getting a stacktrace across multiple threads causes
linecache's cache to bust and del to be called on the global cache variable.
This is not thread safe and raises a KeyError.
Reproducible with,
import threading
import traceback
def main():
with open(__file__, 'a') as fp:
fp.write(' ')
traceback.format_stack()
threads = [
threading.Thread(target=main)
for i in range(100)
]
map(lambda t: t.start(), threads)
map(lambda t: t.join(), threads)
I see the following error,
Exception in thread Thread-56:
Traceback (most recent call last):
File "/Users/me/.pyenv/versions/2.7.10/lib/python2.7/threading.py", line 810,
in __bootstrap_inner
self.run()
File "/Users/me/.pyenv/versions/2.7.10/lib/python2.7/threading.py", line 763,
in run
self.__target(*self.__args, **self.__kwargs)
File "test.py", line 7, in main
traceback.format_stack()
File "/Users/me/.pyenv/versions/2.7.10/lib/python2.7/traceback.py", line 279,
in format_stack
return format_list(extract_stack(f, limit))
File "/Users/me/.pyenv/versions/2.7.10/lib/python2.7/traceback.py", line 305,
in extract_stack
linecache.checkcache(filename)
File "/Users/me/.pyenv/versions/2.7.10/lib/python2.7/linecache.py", line 69,
in checkcache
del cache[filename]
KeyError: 'test.py'
Possible solution is to ignore KeyError on del cache[filename].
----------
components: Library (Lib)
messages: 256469
nosy: Michael Allen
priority: normal
severity: normal
status: open
title: multithreading traceback KeyError when modifying file
type: crash
versions: Python 2.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue25872>
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