Re: Opportunistic GC

[Pip Cet]

On Mon, Mar 8, 2021 at 8:26 AM martin rudalics <rudalics@gmx.at> wrote:
>  > For me, it was a bit difficult to see that this would indeed be safe,
>  > but I'm now pretty convinced it would be: objects that are unreachable
>  > in the child Emacs cannot become reachable in the parent Emacs (they
>  > might show up on the stack, but that's a false positive).
>
> How would this handle the standard problem of the Lisp thread storing a
> pointer to an unmarked object A in an already marked object B and
> releasing all other pointers to A?

We fork(), we don't clone(). If A exists at the time of fork() but
isn't reachable through the thread's stack, that's a bug anyway; if it
doesn't exist yet at the time of fork(), it's not collected in this
cycle.

Did I miss something?

(Other than weak hash tables, of course, which may resurrect
unreachable objects, but I intend to handle those...)

Pip