bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Thu, 12 Mar 2020 20:00:13 +0000
> Cc: 39962@debbugs.gnu.org, Paul Eggert <eggert@cs.ucla.edu>
> 
> The first attachment to this message is an Elisp file which does the
> same thing, by creating thousands of symbols. On GNU/Linux, with
> fairly default standard stack size settings, I get a segfault after
> some 85,000 symbols have been created.

The default stack size on GNU/Linux is 2MB, right?  Maybe it's high
time we raised that, what with the memory size today's machines
routinely have at their disposal.  FWIW, the MS-Windows build have
been using a 8MB run-time stack for a very long time.

Of course, given enough recursive data structures we can always crash
the current GC the way it is implemented.  But the question is how
many such recursive symbols are there in Pieter's sessions? are they
anywhere near the 1000000000 mark you used in your test program?  IOW,
I think we need to know how close we are in real-life sessions to the
dangerous mark.

Maybe this is also worth reporting to VM developers.  They might
consider changing their implementation to avoid these problems.

Thanks.