Issue #14718 has been updated by bluz71 (Dennis B).


sam.saffron (Sam Saffron) wrote:
> After spending a bit too much time thinking about this, I would like to recommend **against** any jemalloc related changes and instead to double down on Eric's https://bugs.ruby-lang.org/issues/14759 for the next release of Ruby (which I think should be backported to 2.5/2.4) 

I was as big a supporter of changing to jemalloc as anyone (and I still use it in production myself); but a little while ago I came to the same conclusion. Ruby should not default to using jemalloc.

Implementing [#14759](https://bugs.ruby-lang.org/issues/14759) is the appropriate, and safe, medium-term solution **until** Guilds land. In the meantime hopefully the glibc folks can do their analysis and improve RSS behaviour especially with the Ruby-based [Fluentd](https://www.fluentd.org/) application causing grief to the Red Hat folks (an excellent pain point motivator to fix glibc). If glibc were fixed then `M_ARENA_MAX=2` should only be applied to older glibc versions effected, via a runtime check?

I think most of the core promoters of this issue: Mike Perham, Sam, Eric and myself would prefer that 14759 be done instead, and possibly close this one?

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Feature #14718: Use jemalloc by default?
https://bugs.ruby-lang.org/issues/14718#change-73270

* 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.

---Files--------------------------------
glibc_arena_2.png (7.23 KB)
jemalloc.png (21.1 KB)
glibc-arena-2.log (60.3 KB)
glibc.log (62.3 KB)
jemalloc-3-5.log (58.5 KB)
glibc.png (9.03 KB)


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