[issue28422] multiprocessing Manager mutable type member access failure

[Irit Katriel]

Irit Katriel  added the comment:

Thank you.

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stage:  -> resolved
status: pending -> closed

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[issue28422] multiprocessing Manager mutable type member access failure

[Vilnis Termanis]

Vilnis Termanis  added the comment:

Apologies, my mistake - it does indeed work with 3.9 & 3.10. Feel free to close.

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resolution:  -> works for me
status: open -> pending
versions: +Python 3.8

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[issue28422] multiprocessing Manager mutable type member access failure

[Irit Katriel]

Irit Katriel  added the comment:

Version 3.8 is in security fix only mode. Is this a problem on newer versions?

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[issue28422] multiprocessing Manager mutable type member access failure

[Vilnis Termanis]

Vilnis Termanis  added the comment:

If you un-comment the print_exc() call, you'll see that it still fails - for 
queue.Queue:

Manager failure (for Queue)
Traceback (most recent call last):
  File "fish.py", line 74, in main
add_type_in_own_process(mgr, type_name)
  File "fish.py", line 61, in add_type_in_own_process
use_manager(obj, type_name, mgr=mgr)
  File "fish.py", line 35, in use_manager
obj.append(getattr(mgr, type_name)())
  File "", line 2, in append
  File "/usr/lib/python3.8/multiprocessing/managers.py", line 850, in 
_callmethod
raise convert_to_error(kind, result)
multiprocessing.managers.RemoteError: 
---
Traceback (most recent call last):
  File "/usr/lib/python3.8/multiprocessing/managers.py", line 243, in 
serve_client
request = recv()
  File "/usr/lib/python3.8/multiprocessing/connection.py", line 251, in recv
return _ForkingPickler.loads(buf.getbuffer())
  File "/usr/lib/python3.8/multiprocessing/managers.py", line 959, in 
RebuildProxy
return func(token, serializer, incref=incref, **kwds)
TypeError: AutoProxy() got an unexpected keyword argument 'manager_owned'
---

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resolution: works for me -> 
status: pending -> open

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[issue28422] multiprocessing Manager mutable type member access failure

[Irit Katriel]

Irit Katriel  added the comment:

I don't get any errors from the attached script. Is there still a problem here?

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resolution:  -> works for me
status: open -> pending

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[issue28422] multiprocessing Manager mutable type member access failure

[Ned Deily]

Changes by Ned Deily :


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nosy: +davin

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[issue28422] multiprocessing Manager mutable type member access failure

[Vilnis Termanis]

Changes by Vilnis Termanis :


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type: crash -> behavior

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[issue28422] multiprocessing Manager mutable type member access failure

[Vilnis Termanis]

Changes by Vilnis Termanis :


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type:  -> crash

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[issue28422] multiprocessing Manager mutable type member access failure

[Vilnis Termanis]

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', )

.. and in underlying manager:
_pickle.PicklingError: Can't pickle : 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

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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

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