From: msiegel@...
Date: 2019-03-14T16:52:06+00:00
Subject: [ruby-core:91832] [Ruby trunk Feature#14718] Use jemalloc by	default?

Issue #14718 has been updated by RubyBugs (A Nonymous).


Does Hongli Lai's article _What causes Ruby memory bloat?_ shed any potential light here?
https://www.joyfulbikeshedding.com/blog/2019-03-14-what-causes-ruby-memory-bloat.html#a-magic-trick-trimming

After investigation, he discovered that patching Ruby to add into `gc_prof_timer_start` a call to  `malloc_trim(0);` demonstrated significant impact, on the same order as using jemalloc in his test application.



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Feature #14718: Use jemalloc by default?
https://bugs.ruby-lang.org/issues/14718#change-77102

* 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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