[ruby-core:86736] [Ruby trunk Feature#14718] Use jemalloc by default?

[rr.rosas@gmail.com]

Issue #14718 has been updated by rosenfeld (Rodrigo Rosenfeld Rosas).


Regarding performance, it's always subjective as always. What are your server's specifications? Usually RAM is not cheap, which means people don't usually have plenty of RAM in their servers, which means that lots of RAM usage could mean that applications are swapping a lot which means they get really slow. You see, there's always trade-offs regarding CPU cycles versus RAM when we talk about performance, because the surrounding environment matters a lot, so I find it really weird to set a goal for a generic programming language to become 3x faster as it doesn't mean anything to me... A benchmark could finish 3 times faster but that doesn't mean some application could become 3 times faster after switching to Ruby 3, for example. It could make no difference at all. However, if jemalloc allows RAM usage to be greatly reduced, then it makes all difference alone.

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Feature #14718: Use jemalloc by default?
https://bugs.ruby-lang.org/issues/14718#change-71691

* 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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