Re: igc, macOS avoiding signals

[Helmut Eller]

On Thu, Jan 02 2025, Eli Zaretskii wrote:

> The problem is that evidently (at least on Posix platforms), if a
> program that uses MPS runs application code from a SIGPROF or a
> SIGALRM or a SIGCHLD signal handler can trigger a recursive access to
> the MPS arena, which causes a fatal signal if that happens while MPS
> holds the arena lock.  So we want to ask for a callback when MPS is
> about to lock the arena, and another callback immediately after it
> releases the lock.  With that, we could defer the application code of
> these signal handlers until after the arena is free to be accessed
> again.

The functions to change would most likely be AreaEnter and ArenaLeave.
As alternative to callbacks, we could give the Arena a signal mask.

Arenas can be created with the function mps_arena_create_k.  This
accepts keyword arguments.  So the callbacks or signal mask could be
given with a new keyword argument.

Helmut