From: hans@...
Date: 2014-06-01T19:27:02+00:00
Subject: [ruby-core:62881] [ruby-trunk - Feature #9113] Ship Ruby for Linux with jemalloc out-of-the-box

Issue #9113 has been updated by Hans de Graaff.


Eric Wong wrote:
> ko1@atdot.net wrote:
>  > I want to suggest only add "--enable-jemalloc" (not default).
>  
>  I am considering it, but I am not sure non-default is worth it over
>  nobu's original suggestion of using "./configure LIBS=-ljemalloc"

Speaking from the Gentoo perspective: with "--enable-jemalloc" I could give my Gentoo users a choice of enabling jemalloc via our "USE flag" mechanism. I'd rather not do that with the LIBS mechanism since then I cannot be sure that this is a maintained and supported configuration.

>  Fwiw, I am mildly against bundling jemalloc in the tarball.  It is
>  more to maintain and keep up-to-date.  Varnish no longer bundles
>  jemalloc for this reason, either.

In Gentoo we would always remove or ignore the bundled version and build against our system version.

----------------------------------------
Feature #9113: Ship Ruby for Linux with jemalloc out-of-the-box
https://bugs.ruby-lang.org/issues/9113#change-47000

* Author: Sam Saffron
* Status: Feedback
* Priority: Normal
* Assignee: 
* Category: build
* Target version: 
----------------------------------------
libc's malloc is a problem, it fragments badly meaning forks share less memory and is slow compared to tcmalloc or jemalloc. 

both jemalloc and tcmalloc are heavily battle tested and stable. 

2 years ago redis picked up the jemalloc dependency see: http://oldblog.antirez.com/post/everything-about-redis-24.html 

To quote antirez:
``
But an allocator is a serious thing. Since we introduced the specially encoded data types Redis started suffering from fragmentation. We tried different things to fix the problem, but basically the Linux default allocator in glibc sucks really, really hard. 
``

--- 

I recently benched Discourse with tcmalloc / jemalloc and default and noticed 2 very important thing: 

median request time reduce by up to 10% (under both)
PSS (proportional share size) is reduced by 10% under jemalloc and 8% under tcmalloc.

We can always use LD_PRELOAD to yank these in, but my concern is that standard distributions are using a far from optimal memory allocator. It would be awesome if the build, out-of-the-box, just checked if it was on Linux  (eg: https://github.com/antirez/redis/blob/unstable/src/Makefile#L30-L34 ) and then used jemalloc instead. 

---Files--------------------------------
0001-configure.in-add-with-jemalloc-option.patch (1.29 KB)


-- 
https://bugs.ruby-lang.org/