Hacker News Reader

Full thread

jhoechtl

Boy I lost track of all the Ruby Jit attempts.

According to the computer language shootout all micro-optimizations

View on HN

YJIT sped up my Rails app by about 30%. It has a memory overhead, but it's worth it.

That is huge, did it also reduce(~~bring in~~) tail latency?

*edit, fix confusing vernacular

Nope -- P99 also decreased. I've heard similar things for other Rails apps as well.

Sorry, in my usage "bring in" means move tail latency P99/P100 more to the left not as introduce, I'll be more clear next time.

So yes! That is great news.

For anyone curious, we've been working to reduce the memory overhead and have added some stats to keep track of memory usage over time. On this graph, you can see a comparison with the CRuby interpreter:

https://speed.yjit.org/memory_timeline#railsbench

What happened on jun 14? (the dramatic drop in memory usage)

Edit: I guess this (https://github.com/ruby/ruby/pull/5944) PR was merged.

Yes. Prior to that point we used to allocate a large chunk of executable memory upfront. We switched to mapping that memory on demand, and that alone was a huge improvement.

https://ruby-compilers.com/ is a comprehensive list of the various Ruby compilers. There's a table summarizing them along with detailed descriptions for some.

Reply on news.ycombinator.com