bug#25875: 26.0.50; Hang logging out of MS-Windows

[Richard Copley]

On 28 February 2017 at 03:30, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Richard Copley <rcopley@gmail.com>
>> Date: Mon, 27 Feb 2017 21:09:52 +0000
>> Cc: Ken Brown <kbrown@cornell.edu>, 25875@debbugs.gnu.org
>>
>> >> Posting a message and then sleeping while it's processed is odd,
>> >> isn't it? If the input thread /sent/ its message to the main thread,
>> >> then while waiting for SendMessage to return, the input thread would
>> >> automatically continue to process sent messages
>> >
>> > No, it's the main thread that calls SendMessage, to tell the input
>> > thread to draw something.  And since the input thread is inside
>> > 'sleep', the SendMessage call never returns, and the main thread never
>> > gets around to checking its input queue, where there's an event bound
>> > to kill-emacs, waiting to be processed.
>>
>> Please Eli, read what I said again. It might not be right, but you
>> misunderstood it.
>> I know the input thread isn't calling SendMessage. It's callling PostMessage 
>> and
>> then sleep. I'm suggesting that the input thread should call SendMessage.
>
> The input thread doesn't call PostMessage.  It calls post_message,
> which is a private messaging mechanism between the input thread and
> the main thread, implemented in w32xfns.c and based on a critical
> section.  IOW, we don't use the Windows messaging in that case.  So I
> don't see how calling SendMessage will help in this situation.  Am I
> missing something?

I see, thanks.