Issue #14759 has been updated by bluz71 (Dennis B).


Hongli Lai's [What causes Ruby memory bloat?](https://www.joyfulbikeshedding.com/blog/2019-03-14-what-causes-ruby-memory-bloat.html) post is most-interesting indeed.

That article has given rise to a new issue, opened by Sam Saffron, [Introduce malloc_trim(0) in full gc cycles #15667](https://bugs.ruby-lang.org/issues/15667).

If `malloc_trim` does not have any deleterious performance demons (to-be-determined) then there would be a very strong case to add a call to it in the the Ruby GC hence rendering this issue completely moot.

We await real-world results of [#15667](https://bugs.ruby-lang.org/issues/15667)

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Feature #14759: [PATCH] set M_ARENA_MAX for glibc malloc
https://bugs.ruby-lang.org/issues/14759#change-77112

* Author: normalperson (Eric Wong)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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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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