bug#45200: [PATCH] Force Glibc to free the memory freed

[Eli Zaretskii]

> From: DJ Delorie <dj@redhat.com>
> Cc: Hi-Angel@yandex.ru, 45200@debbugs.gnu.org, monnier@iro.umontreal.ca,
>         carlos@redhat.com, fweimer@redhat.com
> Date: Mon, 25 Jan 2021 17:17:27 -0500
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> > Thanks, but is it really a good idea to call malloc_trim each time we
> > free some chunk of memory?
> 
> malloc_trim() is very expensive relative to free(), partly because of
> what it needs to do, and partly because it flushes the fastbins cache.

How expensive?  Can you give some quantitative measure?

> If you call it every, say, 1000 iterations of free, that might suffice.
> Or perhaps after each GC run.

There's no guarantee that a full GC will call 'free', even though
that's quite likely.