Re: Concurrency via isolated process/thread

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
> Date: Wed, 05 Jul 2023 13:26:54 +0000
> 
> > If Emacs is to take any more advantage of SMP systems, it
> > must be properly interlocked, with multiple processors sharing the same
> > memory.  This lesson was learned decades ago with another program:
> > vmunix.
> 
> AFAIU, one of the big blockers of this is single-threaded GC. Emacs
> cannot free/allocate memory asynchronously. Or do I miss something?

Why is that a "big blocker"?  GC runs "whenever it is convenient"
anyway, so it can be delayed until that time, and run from the main
thread, perhaps sacrificing the memory footprint a bit.

The real "big blocker" is that a typical Emacs session has a huge
global state, which cannot be safely modified by more than a single
thread at a time, and even if one thread writes while the other reads
is in many cases problematic.