Re: igc, macOS avoiding signals

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: eller.helmut@gmail.com,  pipcet@protonmail.com,  spd@toadstyle.org,
>   emacs-devel@gnu.org
> Date: Tue, 31 Dec 2024 15:15:04 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > If the problem is other signals in [t1, t2], we could install the
> > signal handler in a way that masks all other signals while the handler
> > runs.
> 
> That would be necessary, but there's another thing Helmut pointed out.
> At t0, when we enter the SIGPROF handler, we may have interrupted
> pthread code in the Emacs thread, so pthread may currently be in an
> inconsistent state.

If that really can happen, then pthreads is more fragile than I hoped.
I hoped they don't let signals interrupt them when they are in
critical sections like that.  Are we sure this danger is real?

> I'd like to instead revive the idea of getting the backtrace in the
> signal handler and doing anything else elsewhere.

If it works, sure.  But I thought copying the data had the same
problems as accessing it from the handler?

> Maybe, after reading igc.org, that is acceptable maintenance-wise?

Can you show a patch?