Re: Some experience with the igc branch

[Eli Zaretskii <eliz@gnu.org>]

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>,  pipcet@protonmail.com,  ofv@wanadoo.es,
>  emacs-devel@gnu.org,  acorallo@gnu.org
> Date: Wed, 25 Dec 2024 15:43:21 +0100
> 
> On Wed, Dec 25 2024, Gerd Möllmann wrote:
> 
> > A problem occurs only, apparently (I've not read the MPS code), when the
> > barrier handling code in MPS is called while being in another signal
> > handler like Emacs' SIGPROF handler.
> >
> >
> > I don't know what exactly the problem is in the end, in MPS. That would
> > be a good question for Richard Brooksby, I think.
> 
> The problem is probably simply that MPS uses a non-recursive lock.  The
> SIGSEGV signal handler can't claim the lock when it's already claimed.
> 
> See:
> https://memory-pool-system.readthedocs.io/en/latest/design/arena.html#locks

Which means we should try talking to the MPS folks so that they
provide us with the means of blocking some signals while the lock is
held.  Like some callback MPS would call when it takes the lock and
another one when it releases the lock.  I cannot imagine that Emacs is
the first program that uses signals which hits this issue.  E.g., can
MPS-based programs be built with -pg and then profiled?