[issue35866] concurrent.futures deadlock
cagney
report at bugs.python.org
Wed Apr 17 22:34:06 EDT 2019
cagney <andrew.cagney at gmail.com> added the comment:
So:
#1 we've a bug: the single-threaded ProcessPoolExecutor test program should work 100% reliably - it does not
#2 we've a cause: ProcessPoolExecutor is implemented internally using an unfortunate combination of fork and threads, this is causing the deadlock
#3 we've got a workaround - something like:
ProcessPoolExecutor(multiprocessing.get_context('spawn'))
but I'm guessing, the documentation is scant.
As for a fix, maybe:
- have ProcessPoolExecutor use 'spawn' by default; this way things always work
- have ProcessPoolExecutor properly synchronized its threads before "spawning"/"forking"/... so that "single-threaded" code works
- document that combining ProcessPoolExecutor's "fork" option and user threads isn't a good idea
----------
_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue35866>
_______________________________________
More information about the Python-bugs-list
mailing list