Re: Some experience with the igc branch

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>,  ofv@wanadoo.es,  emacs-devel@gnu.org,
>   eller.helmut@gmail.com,  acorallo@gnu.org
> Date: Mon, 23 Dec 2024 18:44:42 +0100
> 
> BTW, do you know which signal handlers use Lisp, i.e. allocate Lisp
> objects or access some? All? Or, would it be realistic to rewrite signal
> handlers to not do that?

SIGPROF does (it's the basis for our Lisp profiler).

SIGCHLD doesn't run Lisp (I think), but it examines objects and data
structures of the Lisp machine (those related to child processes).

> One thing I've seen done elsewhere is to publish a message to a message
> board so that it can be handled outside of the signal handler. Something
> like that, you know what I mean.

This is tricky for the profiler, because you want to sample the
function in which you are right there and then, not some time later.

For SIGCHLD this could work, but it might make Emacs slower in
handling subprocesses (there are some Lisp packages that fire
subprocesses at very high rate).