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bpo-26153: crasher for warnings + del + interpreter shutdown #6518

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Merged
Yhg1s merged 2 commits into from
May 31, 2018
Merged

bpo-26153: crasher for warnings + del + interpreter shutdown #6518

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1af5175
Add a crasher to Lib/test for issue #26153. This crasher doesn't crash
Yhg1s Apr 18, 2018
4b836c6
Merge branch '2.7' into 2.7-warnings-del-crasher
Yhg1s Apr 25, 2018
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29 changes: 29 additions & 0 deletions Lib/test/crashers/warnings_del_crasher.py
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"""
Expose a race in the _warnings module, which is the C backend for the
warnings module. The "_warnings" module tries to access attributes of the
"warnings" module (because of the API it has to support), but doing so
during interpreter shutdown is problematic. Specifically, the call to
PyImport_GetModuleDict() in Python/_warnings.c:get_warnings_attr will
abort() if the modules dict has already been cleaned up.

This crasher is timing-dependent, and more threads (NUM_THREADS) may be
necessary to expose it reliably on different systems.
"""

import threading
import warnings

NUM_THREADS = 10

class WarnOnDel(object):
def __del__(self):
warnings.warn("oh no something went wrong", UserWarning)

def do_work():
while True:
w = WarnOnDel()

for i in range(NUM_THREADS):
t = threading.Thread(target=do_work)
t.setDaemon(1)
t.start()