Issue #9113 has been updated by kosaki (Motohiro KOSAKI).


@duerst It is not correct. I and glibc folks are working on several improvement about malloc. Moreover, each allocator has different pros/cons. jemalloc can retrieve some workload better and glibc allocator can retrieve some other workload. There is no single perfect allocator. That's our difficulty. 

@sam.saffron The Facebook's page you pointed out is out of date. It compare glibc 2.5 vs jemalloc 2.1.0. But latest are glibc 2.18 and jemalloc 3.4.1. And, glibc malloc and jemalloc shares a lot of basic design. So, this documentation is completely useless. If
you have several workload which glibc doesn't work well, please make and share benchmark instead of rumor. Then, we can improve several bottlenecks.
----------------------------------------
Feature #9113: Ship Ruby for Linux with jemalloc out-of-the-box
https://bugs.ruby-lang.org/issues/9113#change-43069

Author: sam.saffron (Sam Saffron)
Status: Rejected
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. 


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