[Python-Dev] Interrupt thread.join() with Ctrl-C (original) (raw)

[Python-Dev] Interrupt thread.join() with Ctrl-C / KeyboardInterrupt on Windows

Antoine Pitrou solipsis at pitrou.net
Wed Aug 9 03:58:30 EDT 2017

On Tue, 8 Aug 2017 14:29:41 -0700 Steve Dower <steve.dower at python.org> wrote:

On 08Aug2017 1151, Nathaniel Smith wrote: > It looks like Thread.join ultimately ends up blocking in > Python/threadnt.h:EnterNonRecursiveMutex, which has a maze of #ifdefs > behind it -- I think there are 3 different implementation you might > end up with, depending on how CPython was built? Two of them seem to > ultimately block in WaitForSingleObject, which would be easy to adapt > to handle control-C. Unfortunately I think the implementation that > actually gets used on modern systems is the one that blocks in > SleepConditionVariableSRW, and I don't see any easy way for a > control-C to interrupt that. But maybe I'm missing something -- I'm > not a Windows expert.

I'd have to dig back through the recent attempts at changing this, but I believe the SleepConditionVariableSRW path is unused for all versions of Windows. A couple of people (including myself) attempted to enable that code path, but it has some subtle issues that were causing test failures, so we abandoned all the attempts. Though ISTR that someone put in more effort than most of us, but I don't think we've merged it (and if we have, it'd only be in 3.7 at this stage).

For the record, there are issues open for this:

Having Lock.acquire() be interruptible would be really nice as it's the basis for so many of our synchronization primitives (including Thread.join(), I believe).

Regards

Antoine.

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