From: shyouhei@...
Date: 2018-05-11T01:31:04+00:00
Subject: [ruby-core:86975] [Ruby trunk Feature#14718] Use jemalloc by	default?

Issue #14718 has been updated by shyouhei (Shyouhei Urabe).


So, I think it's clear people are interested in replacing _glibc_ malloc, not everything that exist in the whole universe.

Let's discuss how we achieve that.  There can be several ways:

- Just enable `--with-jemalloc` default on, only for Linux.
    - pro: This is the easiest to implement.
    - pro: Arguably works well. Already field proven.
    - con: Mandates runtime dependency for libjemalloc on those systems.
- Detect glibc on startup and try linking jemalloc then.
    - pro: Even works on systems without jemalloc.
    - con: Sacrifices process bootup time, which is a bad thing.
    - con: Tricky to implement, prone to bug.
- Bundle jemalloc and link it statically.
    - pro: No runtime hell.
    - con: Bloats source distribution.  Costs non-glibc users.
    - con: Also costs the core devs because they have to sync the bundled jemalloc with the upstream.

Any opinions?  Or any other ways?

----------------------------------------
Feature #14718: Use jemalloc by default?
https://bugs.ruby-lang.org/issues/14718#change-71940

* Author: mperham (Mike Perham)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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I know Sam opened #9113 4 years ago to suggest this but I'm revisiting the topic to see if there's any movement here for Ruby 2.6 or 2.7.  I supply a major piece of Ruby infrastructure (Sidekiq) and I keep hearing over and over how Ruby is terrible with memory, a huge memory hog with their Rails apps.  My users switch to jemalloc and a miracle occurs: their memory usage drops massively.  Some data points:

https://twitter.com/brandonhilkert/status/987400365627801601
https://twitter.com/d_jones/status/989866391787335680
https://github.com/mperham/sidekiq/issues/3824#issuecomment-383072469

Redis moved to jemalloc many years ago and it solved all of their memory issues too.  Their conclusion: the glibc allocator "sucks really really hard". http://oldblog.antirez.com/post/everything-about-redis-24.html

This is a real pain point for the entire Rails community and would improve Ruby's reputation immensely if we can solve this problem.



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