[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[sbt]

sbt  added the comment:

> I think a generic solution must be found for multiprocessing, so I'll 
> create a separate issue.

I have submitted a patch for Issue 4892 which makes connection and socket 
objects picklable.  It uses socket.share() and socket.fromshare() on Windows.

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Kristján Valur Jónsson]

Kristján Valur Jónsson  added the comment:

possibly, multiprocessing.Connection uses handles, which can be socket handles 
on windows, and that code also uses DuplicateHandle.  I think a generic 
solution must be found for multiprocessing, so I'll create a separate issue.

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Antoine Pitrou]

Antoine Pitrou  added the comment:

> multiprocessing.reduction still appears to use DuplicateHandle to copy 
> sockets.

It's probably a separate issue, then. This one is about 
multiprocessing.connection :)

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Kristján Valur Jónsson]

Kristján Valur Jónsson  added the comment:

multiprocessing.reduction still appears to use DuplicateHandle to copy sockets.
I propose adding a pair of custom functions to _multiprocessing, that "pickles" 
and "unpickles" handles.  It can detect socket handles as being different from 
e.g. pipe handles by using WSADuplicateSocket and return a bytes object, 
similar to what is already done in socketmodule (see issue 14310)
On non-windows, this would be a no-op.
_multiprocessing already linkes with winsock, whereas the subprocess is part of 
python core which doesn't.

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status: closed -> open

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Antoine Pitrou]

Antoine Pitrou  added the comment:

Patch committed, thank you!

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resolution:  -> fixed
stage: patch review -> committed/rejected
status: open -> closed
versions:  -Python 3.2

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Roundup Robot]

Roundup Robot  added the comment:

New changeset f8a92fd084c2 by Antoine Pitrou in branch 'default':
Issue #14522: Avoid duplicating socket handles in multiprocessing.connection.
http://hg.python.org/cpython/rev/f8a92fd084c2

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[sbt]

sbt  added the comment:

> Is there a reason the patch changes close() to win32.CloseHandle()?

This is a Windows only code path so close() is just an alias for 
win32.CloseHandle().  It allow removal of the lines 

# Late import because of circular import
from multiprocessing.forking import duplicate, close

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Antoine Pitrou]

Antoine Pitrou  added the comment:

Is there a reason the patch changes close() to win32.CloseHandle()?

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components: +Library (Lib)
nosy: +pitrou
stage:  -> patch review
type:  -> behavior
versions: +Python 3.2, Python 3.3

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[sbt]

sbt  added the comment:

Actually Issue 9753 was causing failures in test_socket.BasicTCPTest and 
test_socket.BasicTCPTest2 on at least one Windows XP machine.

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[sbt]

sbt  added the comment:

> What is the bug that this fixes? Can you provide a test case?

The bug is using an API in a way that the documentation says is 
wrong/unreliable.  There does not seem to be a classification for that.

I have never seen a problem caused by using DuplicateHandle() so I cannot 
provide a test case.  Note that socket.dup() used to be implemented using 
DuplicateHandle(), but that was changed to WSADuplicateSocket().  See Issue 
9753.

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Added file: http://bugs.python.org/file25154/mp_socket_dup.patch

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[sbt]

Changes by sbt :


Removed file: http://bugs.python.org/file25153/mp_socket_dup.patch

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[Martin v . Löwis]

Martin v. Löwis  added the comment:

What is the bug that this fixes? Can you provide a test case?

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[issue14522] Avoid using DuplicateHandle() on sockets in multiprocessing.connection

[sbt]

New submission from sbt :

In multiprocessing.connection on Windows, socket handles are indirectly 
duplicated using DuplicateHandle() instead the WSADuplicateSocket().  According 
to Microsoft's documentation this is not supported.

This is easily avoided by using socket.detach() instead of duplicating the 
handle.

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files: mp_socket_dup.patch
keywords: patch
messages: 157747
nosy: sbt
priority: normal
severity: normal
status: open
title: Avoid using DuplicateHandle() on sockets in multiprocessing.connection
Added file: http://bugs.python.org/file25153/mp_socket_dup.patch

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