Issue #14759 has been updated by ko1 (Koichi Sasada).


sam.saffron (Sam Saffron) wrote:
> Koichi / Nobu
>  
> Is there any chance we can merge this in and even backport to 2.4/2.5. 
> 
> It is a very safe change for now and users can override the behavior if they need to using ENV (rare cases where you say host a ton of V8 runtimes) 
> 
> It will give Ruby a much better reputation to have this out there and guilds are a few releases out.

We are not maintainers for both versions, but I think we shouldn't backport it because we can change this parameter by an environment variable.


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Feature #14759: [PATCH] set M_ARENA_MAX for glibc malloc
https://bugs.ruby-lang.org/issues/14759#change-73371

* Author: normalperson (Eric Wong)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Not everybody benefits from jemalloc and the extra download+install
time is not always worth it.  Lets make the user experience for
glibc malloc users better, too.

Personally, I prefer using M_ARENA_MAX=1 (via MALLOC_ARENA_MAX
env) myself, but there is currently a performance penalty for
that.


gc.c (Init_GC): set M_ARENA_MAX=2 for glibc malloc

glibc malloc creates too many arenas and leads to fragmentation.
Given the existence of the GVL, clamping to two arenas seems
to be a reasonable trade-off for performance and memory usage.

Some users (including myself for several years, now) prefer only
one arena, now, so continue to respect users' wishes when
MALLOC_ARENA_MAX is set.

Thanks to Mike Perham for the reminder [ruby-core:86843]


This doesn't seem to conflict with jemalloc, so it should be safe
for all glibc-using systems.


---Files--------------------------------
0001-gc.c-Init_GC-set-M_ARENA_MAX-2-for-glibc-malloc.patch (1.46 KB)


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