[issue39847] EnterNonRecursiveMutex on win32 can hang for 49.7 days

[And Clover]

New submission from And Clover <and at doxdesk.com>:

Since bpo-15038, waiting to acquire locks/events/etc from _thread/threading on Windows can fail to return long past the requested timeout. Cause:

https://github.com/python/cpython/blob/3.8/Python/thread_nt.h#L85

using 32-bit GetTickCount/DWORD, which will overflow at around 49.7 days of uptime.

If the WaitForSingleObjectEx call in PyCOND_TIMEDWAIT returns later than the 'target' time, and the tick count overflows in that gap, 'milliseconds' will become very large (up to another 49.7 days) and the next PyCOND_TIMEDWAIT will be stuck for a long time.

Where we've seen it is where it's most likely to happen: when the machine is hibernated during the WaitForSingleObjectEx call. I believe the TickCount continues to increase during hibernation so there is a much bigger gap between 'target' and 'now' for the overflow to happen in.

Simplest fix is probably to switch to GetTickCount64/ULONGLONG. We should be able to get away with using this now we no longer support WinXP.

----------
components: Library (Lib), Windows
messages: 363346
nosy: aclover, paul.moore, steve.dower, tim.golden, zach.ware
priority: normal
severity: normal
status: open
title: EnterNonRecursiveMutex on win32 can hang for 49.7 days
type: behavior
versions: Python 3.5, Python 3.6, Python 3.7, Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue39847>
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