Re: Some experience with the igc branch

[Pip Cet via "Emacs development discussions." <emacs-devel@gnu.org>]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>
>> I've reached the point where I don't know what else to explain. Could
>> always be improved, of course, and so on. Please find attached, with
>> request for feedback.
>
> Ahem, just remembered that I had already an admin/igc.org in the branch,
> so I've now replaced that with what I've written.

Thank you very much!

> - Concurrent.  The GC runs in its own thread.  There are no explicit
>  calls to start GC, and Emacs doesn't have to wait for the GC to
>  complete.

I don't think that's true right now (it is what I want for Christmas,
though).  On GNU/Linux, the GC usually runs on the main thread.  On
macOS, the GC can run on the main thread (allocation) or on the SIGSEGV
handler thread (memory barriers); in both cases, the main thread has to
wait for it to complete.

I'm not sure it's ever useful to make the assumption that GC isn't
concurrent:  it is very hard to do so, but it is possible.

Maybe Eli knows more; I posted a patch to force concurrent GC for
debugging a while ago, and Eli told me not to because it would produce
false positives.  I'm not so sure about the "false" part now.

Pip