[New-bugs-announce] [issue21817] `concurrent.futures.ProcessPoolExecutor` swallows tracebacks
Ram Rachum
report at bugs.python.org
Sat Jun 21 00:13:22 CEST 2014
New submission from Ram Rachum:
When you use `concurrent.futures.ProcessPoolExecutor` and an exception is raised in the created process, it doesn't show you the traceback. This makes debugging very annoying.
Example file:
#!python
import sys
import concurrent.futures
def f():
# Successful assert:
assert True
return g()
def g():
# Hard-to-find failing assert:
assert False
if __name__ == '__main__':
with concurrent.futures.ProcessPoolExecutor(max_workers=1) as executor:
assert isinstance(executor, concurrent.futures.Executor)
future = executor.submit(f)
future.result()
print('Main process finished')
If you run this under Windows, you get this:
Traceback (most recent call last):
File "./bug.py", line 20, in <module>
future.result()
File "c:\python34\lib\concurrent\futures\_base.py", line 402, in result
return self.__get_result()
File "c:\python34\lib\concurrent\futures\_base.py", line 354, in __get_result
raise self._exception
AssertionError
This is the traceback of the main process, while we want the traceback of the process that failed.
----------
components: Library (Lib)
messages: 221128
nosy: cool-RR
priority: normal
severity: normal
status: open
title: `concurrent.futures.ProcessPoolExecutor` swallows tracebacks
type: behavior
versions: Python 3.4
_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21817>
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