Subject: bug#28630: 27.0.50; C-g while a non-main thread is sitting crashes Emacs

From: Philipp Stephani <[email-masked]>
Date: Sat, 07 Oct 2017 13:53:43 +0000

Eli Zaretskii <[email-masked]> schrieb am Do., 5. Okt. 2017 um 09:25 Uhr:

> > Date: Thu, 05 Oct 2017 12:27:28 +0900
> > From: YAMAMOTO Mitsuharu <[email-masked]>
> > Cc: [email-masked],
> >       [email-masked],
> >       [email-masked]
> >
> > >>>>> On Wed, 04 Oct 2017 12:23:19 +0300, Eli Zaretskii <[email-masked]>
> said:
> >
> > >> > OOC, could you please see whether on X the sit-for call is
> > >> > interrupted or not?  That is, do you see the "there" message
> > >> > after typing C-g?
> > Same for NS.  Interestingly, some variants of the original recipe
> > behave differently with respect to C-g depending on the toolkit.
> >
> > Example 1:
> >
> > (thread-join
> >  (make-thread
> >   (lambda ()
> >     (message "hello")
> >     (sit-for 2)
> >     (message "there"))))
> >
> > Interrupted: GTK+, Athena, no toolkit, Mac
> > Not interrupted: NS
> >
> >
> > Example 2:
> >
> > (thread-join
> >  (make-thread
> >   (lambda ()
> >     (message "hello")
> >     (sleep-for 2)
> >     (message "there"))))
> >
> > Interrupted: GTK+
> > Not interrupted: Athena, no toolkit, Mac, NS
>
> For the record, on MS-Windows, both are interrupted.
>
> > Probably it has something to do with xg_select.
>
> Could be.
>
> The upshot of this is that doing keyboard I/O in non-main threads is
> inherently unportable.  Should we mention this in the manual?
>
>
>
>

I'd rather see this as a bug and document it in etc/PROBLEMS.
Also, if the behavior between main and non-main threads differ, there
should probably a `in-main-thread-p' function.