bug#36609: 27.0.50; Possible race-condition in threading implementation

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Fri, 12 Jul 2019 12:44:35 +0000
> Cc: 36609@debbugs.gnu.org
> 
> Okay, I'm still not sure this is really the problem Andreas was
> seeing, but this code fails to work with xg_select:
> 
> (let ((thread (make-thread (lambda ()
>                  (sleep-for 3)))))
>   (thread-yield)
>   (thread-signal thread 'error nil))

What do you mean by "fails"?  What do you see when you eval this?

> Proposed patch attached.

As I said earlier, I don't think it's right to use stack unwinding at
this level.  (Did you try this in a -nw session?)

I'd appreciate a description of what you think happens here, and why.

Thanks.