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From: Helmut Eller <eller.helmut@gmail.com>
To: "Gerd Möllmann" <gerd.moellmann@gmail.com>
Cc: Eli Zaretskii <eliz@gnu.org>,
	 pipcet@protonmail.com,  ofv@wanadoo.es, emacs-devel@gnu.org,
	 acorallo@gnu.org
Subject: Re: SIGPROF + SIGCHLD and igc
Date: Tue, 24 Dec 2024 09:23:11 +0100	[thread overview]
Message-ID: <87ldw55w28.fsf@gmail.com> (raw)
In-Reply-To: <m2o711ehx2.fsf_-_@gmail.com> ("Gerd Möllmann"'s message of "Tue, 24 Dec 2024 07:03:53 +0100")

On Tue, Dec 24 2024, Gerd Möllmann wrote:

[...]
> Anyway, what I see here: SIGCHLD doesn't do anything dangerous in the
> signal handler. Instead, the occurrence of SIGCHLD is added to a queue
> with enqueue_async_work and that's basically it.

Wrong branch!  enqueue_async_work doesn't exist in master.  ISTR that in
master it iterates through process-list.  Also, Pip said something that
the queue is not signal safe, because signals can nest or something like
that.  Also, Eli didn't like enqueue_async_work much.

> My personal summary for SIGPROF + SIGCHLD at this point:
>
> - I recommend rewriting SIGPROF handling in the way I tried to describe,
>   possibly using the existing work queue mechanism. Everything else looks
>   too complicated to me.
>   
> - Lisp allocation in signal handlers cannot exist because alloc.c is not
>   reentrant which means we would crash with the old GC. We don't need
>   anything extra for that in igc.
>
> - No longer wondering why macOS does not show any problems in that whole
>   area. The only problem is SIGPROF accessing Lisp objects, and the
>   memory barrier is not a problem on macOS because it doesn't use
>   signals.
>
> Please double-check!

I think, SIGIO might cause trouble.  But that async IO code in process.c
is sooo hard to read.  I wonder if it would be simpler with threads,
e.g. one thread per Lisp_Process.

Helmut



  reply	other threads:[~2024-12-24  8:23 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-22 15:40 Some experience with the igc branch Óscar Fuentes
2024-12-22 17:18 ` Gerd Möllmann
2024-12-22 17:29 ` Gerd Möllmann
2024-12-22 17:41 ` Pip Cet via Emacs development discussions.
2024-12-22 17:56   ` Gerd Möllmann
2024-12-22 19:11   ` Óscar Fuentes
2024-12-23  0:05     ` Pip Cet via Emacs development discussions.
2024-12-23  1:00       ` Óscar Fuentes
2024-12-23  3:42       ` Gerd Möllmann
2024-12-23  6:27     ` Jean Louis
2024-12-22 20:29   ` Helmut Eller
2024-12-22 20:50   ` Gerd Möllmann
2024-12-22 22:26     ` Pip Cet via Emacs development discussions.
2024-12-23  3:23       ` Gerd Möllmann
     [not found]         ` <m234ieddeu.fsf_-_@gmail.com>
     [not found]           ` <87ttaueqp9.fsf@protonmail.com>
     [not found]             ` <m2frme921u.fsf@gmail.com>
     [not found]               ` <87ldw6ejkv.fsf@protonmail.com>
     [not found]                 ` <m2bjx2h8dh.fsf@gmail.com>
2024-12-23 14:45                   ` Make Signal handling patch platform-dependent? Pip Cet via Emacs development discussions.
2024-12-23 14:54                     ` Gerd Möllmann
2024-12-23 15:11                       ` Eli Zaretskii
2024-12-23 13:35       ` Some experience with the igc branch Eli Zaretskii
2024-12-23 14:03         ` Discussion with MPS people Gerd Möllmann
2024-12-23 14:04           ` Gerd Möllmann
2024-12-23 15:07         ` Some experience with the igc branch Pip Cet via Emacs development discussions.
2024-12-23 15:26           ` Gerd Möllmann
2024-12-23 16:03             ` Pip Cet via Emacs development discussions.
2024-12-23 16:44               ` Eli Zaretskii
2024-12-23 17:16                 ` Pip Cet via Emacs development discussions.
2024-12-23 18:35                   ` Eli Zaretskii
2024-12-23 18:48                     ` Gerd Möllmann
2024-12-23 19:25                       ` Eli Zaretskii
2024-12-23 20:30                     ` Benjamin Riefenstahl
2024-12-23 23:39                       ` Pip Cet via Emacs development discussions.
2024-12-24 12:14                         ` Eli Zaretskii
2024-12-24 13:18                           ` Pip Cet via Emacs development discussions.
2024-12-24 13:42                           ` Benjamin Riefenstahl
2024-12-24  3:37                       ` Eli Zaretskii
2024-12-24  8:48                         ` Benjamin Riefenstahl
2024-12-24 13:52                           ` Eli Zaretskii
2024-12-24 13:54                             ` Benjamin Riefenstahl
2024-12-23 17:44               ` Gerd Möllmann
2024-12-23 19:00                 ` Eli Zaretskii
2024-12-23 19:37                   ` Eli Zaretskii
2024-12-23 20:49                   ` Gerd Möllmann
2024-12-23 21:43                     ` Helmut Eller
2024-12-23 21:49                       ` Pip Cet via Emacs development discussions.
2024-12-23 21:58                         ` Helmut Eller
2024-12-23 23:20                           ` Pip Cet via Emacs development discussions.
2024-12-24  5:38                             ` Helmut Eller
2024-12-24  6:27                               ` Gerd Möllmann
2024-12-24 10:09                               ` Pip Cet via Emacs development discussions.
2024-12-24  4:05                       ` Gerd Möllmann
2024-12-24  8:50                         ` Gerd Möllmann
2024-12-24  6:03                     ` SIGPROF + SIGCHLD and igc Gerd Möllmann
2024-12-24  8:23                       ` Helmut Eller [this message]
2024-12-24  8:39                         ` Gerd Möllmann
2024-12-24 13:05                         ` Eli Zaretskii
2024-12-24 12:54                       ` Eli Zaretskii
2024-12-24 12:59                         ` Gerd Möllmann
2024-12-23 23:37                   ` Some experience with the igc branch Pip Cet via Emacs development discussions.
2024-12-24  4:03                     ` Gerd Möllmann
2024-12-24 10:25                       ` Pip Cet via Emacs development discussions.
2024-12-24 10:50                         ` Gerd Möllmann
2024-12-24 13:15                         ` Eli Zaretskii
2024-12-24 12:26                       ` Eli Zaretskii
2024-12-24 12:56                         ` Gerd Möllmann
2024-12-24 13:19                           ` Pip Cet via Emacs development discussions.
2024-12-24 13:38                             ` Gerd Möllmann
2024-12-24 13:46                           ` Eli Zaretskii
2024-12-24 14:12                             ` Gerd Möllmann
2024-12-24 14:40                               ` Eli Zaretskii
2024-12-24 12:11                     ` Eli Zaretskii

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