[New-bugs-announce] [issue28422] multiprocessing Manager mutable type member access failure
Vilnis Termanis
report at bugs.python.org
Wed Oct 12 09:03:47 EDT 2016
New submission from Vilnis Termanis:
Accessing some Manager types (e.g. Lock) through a list, dict or Namespace proxy is not possible if both the mutable container (e.g. list) and contained type instance (e.g. Lock) have been created in the same process.
Symptoms:
In accessing process:
multiprocessing.managers.RemoteError on access, e.g.:
Unserializable message: ('#RETURN', <thread.lock object at 0x7fcf40d31370>)
.. and in underlying manager:
_pickle.PicklingError: Can't pickle <class '_thread.lock'>: attribute lookup lock on _thread failed
The provided test script performs:
0) Initialise SyncManager (via multiprocessing.Manager())
1) Create list proxy through manager
2) Insert another proxied type into the list (e.g. Lock)
3) Try to access type instance from (2) via container created in (1)
Note: When step (2) is run in a child process, everything work as expected. When all steps execute in the same process, one gets the aforementioned exception.
See also:
https://mail.python.org/pipermail/python-list/2009-September/552988.html
----------
components: Library (Lib)
files: manager_pickling.py
messages: 278529
nosy: vilnis.termanis
priority: normal
severity: normal
status: open
title: multiprocessing Manager mutable type member access failure
versions: Python 2.7, Python 3.5
Added file: http://bugs.python.org/file45066/manager_pickling.py
_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue28422>
_______________________________________
More information about the New-bugs-announce
mailing list