Re: Opportunistic GC

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Pip Cet <pipcet@gmail.com>,  eliz@gnu.org,  emacs-devel@gnu.org
> Date: Mon, 08 Mar 2021 11:44:05 -0500
> 
> > I also expect fork will work, I'm more wondering about interaction with
> > sockets file descriptors or anything else in our codebase and/or in
> > libraries we have loaded.
> 
> I suspect we wouldn't want to use `fork` literally, but rather something
> like Linux's `clone` so as to have more control about what is
> really shared.  Basically, we just want to spawn a thread, except it runs
> in a snapshot of the heap.

There are other potential complications with this, related to
threads.  Posix says 'fork' only copies a single thread, the one that
called it, but what if that single thread is not the main thread?  In
Emacs nowadays a non-main Lisp thread can trigger GC.  What happens to
the mutexes we use in the threads machinery when we fork like that?