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From: Pip Cet <pipcet@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 36609@debbugs.gnu.org, politza@hochschule-trier.de
Subject: bug#36609: 27.0.50; Possible race-condition in threading implementation
Date: Fri, 12 Jul 2019 13:51:48 +0000	[thread overview]
Message-ID: <CAOqdjBe1sVkKMGH4irscrB7orOqUt+80s5HZrB-8orXYUCDAsA@mail.gmail.com> (raw)
In-Reply-To: <83ims72xcj.fsf@gnu.org>

On Fri, Jul 12, 2019 at 1:31 PM Eli Zaretskii <eliz@gnu.org> wrote:>
> > From: Pip Cet <pipcet@gmail.com>
> > Date: Fri, 12 Jul 2019 12:57:51 +0000
> > Cc: politza@hochschule-trier.de, 36609@debbugs.gnu.org
> >
> > Lisp Backtrace:
> > "sleep-for" (0xedf7a530)
> > 0xf6da40 Lisp type 3
> >
> > post_acquire_global_lock () can return abnormally (I didn't know
> > that), so really_call_select() can, too, so thread_select() can, too.
>
> Do you know which code sets current_thread->error_symbol, and what is
> that error symbol?

thread-signal, which my example code calls directly. I passed 'error,
and that's what error_symbol is set to.

last_thread_error is (error) when the Emacs session freezes.

> > > > +  ptrdiff_t count = SPECPDL_INDEX ();
> > >
> > > I don't think we should do that at this low level.
> >
> > You're right, it does stick out. I think we're safe because we're
> > calling Fsignal with the global lock held, but it's not a pretty or
> > well-documented situation.
>
> Is this the main thread which does that?  if so, there should be no
> problem with holding the global lock in this case, is there?
>
> If this is not the main thread, then the error handlers should be set
> so as to log the error in last_thread_error, and then terminate the
> thread (via exiting the thread function, AFAIR).

Indeed, that's what happens; but the thread now fails to release the
GLib lock it had previously acquired, so other threads cannot acquire
it again, ever.

> If this is not what happens, I'd like to know what does happen here,
> and why.

Sure, we should understand what's going on here; even if the fix turns
out to be simple.





  reply	other threads:[~2019-07-12 13:51 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 20:51 bug#36609: 27.0.50; Possible race-condition in threading implementation Andreas Politz
2019-07-12  7:47 ` Eli Zaretskii
2019-07-12  8:05   ` Eli Zaretskii
2019-07-12  9:02 ` Pip Cet
2019-07-12 12:42   ` Eli Zaretskii
2019-07-12 12:57     ` Pip Cet
2019-07-12 13:31       ` Eli Zaretskii
2019-07-12 13:51         ` Pip Cet [this message]
2019-07-12 15:05           ` Eli Zaretskii
2019-07-12 18:06             ` Pip Cet
2019-07-12 18:27               ` Eli Zaretskii
2019-07-12 18:34                 ` Eli Zaretskii
2019-07-12 19:24                   ` Pip Cet
2019-07-12 19:57                     ` Eli Zaretskii
2019-07-13 14:37                       ` Pip Cet
2019-07-13 15:03                         ` Eli Zaretskii
2019-07-13 15:13                           ` Eli Zaretskii
2019-07-13 15:54                           ` Eli Zaretskii
2019-07-13 15:57                             ` Pip Cet
2019-07-13 16:02                               ` Eli Zaretskii
2019-07-13 18:17                                 ` Pip Cet
2020-08-21 12:57                                   ` Lars Ingebrigtsen
2019-07-13 15:04                         ` Andreas Politz
2019-07-12 12:44   ` Pip Cet
2019-07-12 12:55     ` Eli Zaretskii
2019-07-12 13:40       ` Pip Cet
2019-07-12 13:51         ` Eli Zaretskii
2019-07-12 14:34           ` Pip Cet
2019-07-12 15:02             ` Eli Zaretskii
2019-07-12 19:30               ` Pip Cet
2019-07-13  6:50                 ` Eli Zaretskii
2021-06-06 15:50 ` dick.r.chiang
     [not found] ` <87fsxv8182.fsf@dick>
2021-06-06 16:35   ` Eli Zaretskii
2021-06-06 19:10     ` dick.r.chiang
2021-06-06 19:27       ` Eli Zaretskii
2021-06-09 21:40         ` dick.r.chiang
2021-06-10  6:46           ` Eli Zaretskii
2021-06-10 11:52             ` dick.r.chiang
2021-06-10 14:18               ` Eli Zaretskii
2021-06-10 14:55                 ` dick.r.chiang
2021-06-10 15:04                   ` Eli Zaretskii
2021-06-10 21:36                     ` dick.r.chiang
2021-06-11  6:00                       ` Eli Zaretskii
2021-06-19 17:53                         ` Eli Zaretskii
2021-06-19 19:14                           ` dick.r.chiang
2021-06-19 19:18                             ` Eli Zaretskii
2021-06-19 21:12                               ` dick.r.chiang
2021-06-20 11:39                                 ` Eli Zaretskii
2021-06-20 14:01                                   ` dick.r.chiang
2021-06-20 15:53                                     ` Eli Zaretskii
2021-06-25 13:54                                       ` Eli Zaretskii
2021-06-10 15:35                 ` Andreas Schwab
2021-06-10 15:39                   ` Eli Zaretskii

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