Re: Opportunistic GC

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

Pip Cet <pipcet@gmail.com> writes:

> On Mon, Mar 8, 2021 at 2:01 PM Andrea Corallo <akrl@sdf.org> wrote:
>> Pip Cet <pipcet@gmail.com> writes:
>>
>> > On Mon, Mar 8, 2021 at 3:37 AM Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>> >> I've been running with the code below recently to try and see if
>> >> opportunistic GC can be worth the trouble.
>> >
>> > Just a random idea: What if we exploit the fact most people have more
>> > than one CPU core these days, garbage-collect in a separate fork()ed
>> > process, then do only the sweeping in the main process?
>>
>> It's an interesting concept, I thought about something similar in the
>> past but, I've two questions:
>>
>> Are we really sure that a non trivial process can long survive
>> or work as expected after being forked?
>
> I believe that, on all systems where bash works, we can expect fork()
> to behave.

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've read in the past this is an issue in practice in non trivial code
and that, because the typical use of fork () nowadays is just to run
afterward exec (), operating in the grey between the two was not really
a good idea.  But I don't have the reference now and if you say it works
I've no reasons not to trust you.

  Andrea