Re: igc, macOS avoiding signals

[Eli Zaretskii]

> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: Gerd Möllmann <gerd.moellmann@gmail.com>,  Eli
>  Zaretskii <eliz@gnu.org>,
>   spd@toadstyle.org,  emacs-devel@gnu.org
> Date: Mon, 30 Dec 2024 15:59:08 +0100
> 
>   if (mps_arena_busy (<arena>))
>     plog->gc_count = saturated_add (plog->gc_count, count);
>   else
>     record_backtrace (plog, count);
> 
> is safe.  If we don't hold the lock, then mps_arena_busy returns false
> and we can access memory.  We are safe even if another thread has
> claimed the lock by the time that we reach record_backtrace: the SIGPROF
> handler will just block until the lock is released.

Which other thread could have claimed the lock?