A talk on JRuby and how to scale Ruby and Rails applications using it. Delivered at RubyConf Thailand in Bangkok, December 9 2022.
Scaling Ruby with JRubyCharles Oliver Nutter@headius(@mastodon.social)
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Me• Programming my whole life• Professionally since 1996• JRuby since 2006• [email protected]• @headius(@mastodon.social)
RubyConf Thailand 2019
Drag Race Thailand!
Thank You Yarden!• I got to speak at RubyConf!• Tomorrow's JRuby keynote• "Ruby & JVM: A Love Story"• Really cool talk about herexperiences using and buildingapps with JRuby!• @YardenLaif
What is JRuby?• An implementation of Ruby atop the Java Virtual Machine• Ruby implementationfirst, JVM language second• Many benefits from JVM ecosystem• Ruby code should "just work"• Different extension API, no forking, parallel threads• https://www.jruby.org/
Ruby Compatibility• JRuby 9.4 is out now!• Ruby 3.1 compatible, 98% of language specs passing• Nearly complete core + stdlib features from 2.7, 3.0 and 3.1• JRuby 9.3 (Ruby 2.6 compat)• Maintenance through 2023 as needed• Compatibility before performance!• Now we can refocus on optimization again
Ruby 3.2 Coming Soon!• We will set up another checklist issue• You can help us add missing features!• Hopefully release 3.2 compatibility in the next 6 months
Why Ruby on JVM?• Widely deployed and widely supported runtime• Excellent JIT, GC, concurrency, and platform support• Tens of thousands of libraries• Rich tools for monitoring, profiling, debugging• "Write once, run anywhere": JRuby works on many platforms
JVM Tools and GC
Fun Stuff• Glimmer GUI DSL• Multiple backends (SWT, GTK, ...)• JRuby + SWT is the most mature• JRuby makes cross-platform GUImuch easier!• Works same everywhere• GUI libraries shipped with gem
Getting Started
JRuby Install• Install a JDK• Java 11+ recommended, there's many distributions out there• Java 8 supported for 9.4 and lower• Install JRuby• Recommended: system package, Ruby installer, Docker image• Download tarball/zip or Windows installer
Try it out![] ~ $ rvm use jrubyUsing /Users/headius/.rvm/gems/jruby-9.4.0.0[] ~ $ irb:001 > runtime = java.lang.Runtime.runtime=> #:002 > runtime.available_processors=> 8:003 > runtime.free_memory=> 91420584:004 >
JRuby on Rails
JRuby Runs Rails!• Since 2007!• "Are there JRuby users running Rails applications?"• Oh yes! And at large scale!• Benefit from the JVM, libraries, languages• Great way to scale large Rails apps today!
Getting Started• Generate a new app, Rails will use JRuby defaults• Couple gotchas with Rails 7, we can help• Use threads in Puma instead of workers• 2n+1 is a good rule of thumb• Make sure to increase DB connections as well• Existing app: try bundling, replace unsupported libs
Rails 7• Rails 7 works on JRuby 9.4!• ActiveRecord for JRuby needs some updates• Mostly small changes to our ActiveRecord JDBC adapter• Performance and compatibility looking good!• Couple gotchas right now but we're working through them
Rails 7actioncable: 203 runs, 921 assertions, 0 failures, 10 errorsactionmailbox: 92 runs, 238 assertions, 0 failures, 0 errorsactionmailer: 230 runs, 516 assertions, 0 failures, 1 errorsactionpack: 3550 runs, 16802 assertions, 1 failures, 1 errorsactiontext: 80 runs, 145 assertions, 7 failures, 2 errorsactionview: 2424 runs, 5395 assertions, 2 failures, 4 errorsactivejob: 368 runs, 837 assertions, 0 failures, 0 errorsactivemodel: 966 runs, 2853 assertions, 5 failures, 0 errorsactivestorage: 392 runs, 1121 assertions, 0 failures, 0 errorsactivesupport: 5188 runs, 12926 assertions, 43 failures, 28 errors99% passing!
activerecord-jdbc-adapter• Version-matched to Rails• 60.0 for Rails 6.x, 70.0 for Rails 7.x, etc• 70.0 in progress• sqlite, mysql working pretty well, gems are out there• sqlite: 7745 runs, 25040 assertions, 32 failures, 14 errors• postgresql needs more updates, coming soon
Performance and Scaling
What Matters to You?• Straight-line performance?• High concurrency?• Startup time?• Warmup time?• Memory size?• Optimizing for only one of these can penalize the others
Benchmarks• Benchmarks are very situational• What looks good in a microbench may not translate to production• Two example benchmarks• railsbench, small Rails blog on SQLite, no web server, tight loop• Rails blog on MySQL, end to end through Puma
railsbench• Based on simple scaffolded blog app• SQLite database, single thread, all in one process• No web server, no connections, just loop on requests• Good for analyzing Rails core framework performance• Not great for real-world end-to-end measurement
The Players• Ruby 3.1.2 with and without --yjit• TruffleRuby 22.2 JVM CE• Newer versions may be better• JRuby 9.4 on Java 17
time to run 2000 requests (lower is better)0550110016502200Time1,460ms1,550ms1,704ms2,152msCRuby 3.1 CRuby 3.1 yjit TruffleRuby JRuby
What You're Missing• Straight-line performance?• High concurrency?• Startup time?• Warmup time?• Memory size?
Memory Footprint• More complex runtimes take more memory• Different GC strategies take more memory• CRuby has been optimized for startup time and memory use• Super valuable but may not help server apps
Memory Footprint0750150022503000Memory900MB2,400MB80MBCRuby 3.1 TruffleRuby JRuby
Warmup Time• Optimizing runtimes just take longer to warm up• Code needs to be profiled, analyzed, compiled• GC needs tofind sweet spot for heap size, generations• Known issue, but we and JVM folks always try to improve• Pre-warm new deploys (or just accept it will start off slower)• JVM tooling to bootstrap into a warm VM
Warmup Over Time0ms450ms900ms1350ms1800msIteration (2000 requests each)1 2 3 4 5 6 7 8 9 10CRuby 3.1 yjit
Warmup Over Time0ms5000ms10000ms15000ms20000msIteration (2000 requests each)1 2 3 4 5 6 7 8 9 10JRuby
JRuby ArchitectureRuby (.rb)JITJava Instructions(java bytecode)Ruby Instructions(IR)parseinterpretinterpreterinterpretC1 compilenative codebetternative codejavabytecodeinterpreterexecuteC2 compileJava Virtual MachineJRuby InternalsdeoptimizePerformance improves the longer your app runs
Warmup Over Time0ms5000ms10000ms15000ms20000msIteration (2000 requests each)1 2 3 4 5 6 7 8 9 10CRuby 3.1 yjit JRuby
Warmup Over Time0ms6000ms12000ms18000ms24000msIteration (2000 requests each)1 2 3 4 5 6 7 8 9 10TruffleRuby
Warmup Over Time0ms7500ms15000ms22500ms30000msIteration (2000 requests each)1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69CRuby 3.1 yjit TruffleRuby JRuby
Benchmarks Lie• The only benchmark that matters is your code• Your code is probably not requesting the same posts in a loop• We can make this a bit more real• Full end-to-end: Puma web server, MySQL backend• External request driver (siege)• Max out CPU (high concurrency)
Scaling Rails• Classic problem on MRI• No concurrent threads, so we need processes• Processes duplicate runtime state and waste resources• JRuby is the answer!• Multi-threaded single process runs your entire site• Single process with solid GC uses resources better
End-to-end Rails Blog• Scaffolded "blog" application on MySQL• Local i7 laptop• CRuby 3.1: 16 workers, 2 threads each• JRuby 9.4: 32 threads• TruffleRuby: 32 threads but had issues
Setup• Local everything including benchmark driver• MySQL in a Docker container• Scaffolded app is super minimal• Using siege: 16 concurrent, 10s intervals, benchmark mode• Warmup time is a thing...
requests per second (higher is better)0rps1500rps3000rps4500rps6000rps3m5,160rps668rps2,361rps2,070rpsCRuby 3.1 CRuby 3.1 yjit TruffleRuby JVM CE JRuby
1300MB1375MB1450MB1525MB1600MB1,400MB1,520MBRuby 3.1 JRuby
0MB400MB800MB1200MB1600MB950MB1,400MB1,520MBRuby 3.1 JRuby JRuby with max heap
Requests per second, 10s siege runs (higher is better)015003000450060001 2 3 4 5 6 7 8 9 10CRuby 3.1 CRuby 3.1 yjit JRuby
Wrapping Up
True Story• Large Rails application using 40 xlarge on EC2• 40 worker processes per server• 100k-150k req/min, 50-75ms response times• Migrated app to JRuby, made more use of threading• Down to 10 xlarge, 75% cost reduction• Consistently over 150k req/min, 30ms response times
JRuby Future• JRuby 9.4 is out!• Try it out, report issues, submit a PR!• Ongoing Rails 7 updates• Big optimization work coming in the next year• New JVM features• Nativefibers! Built-in FFI!
Thank You!• Charles Oliver Nutter• [email protected]• @headius(@mastodon.social)• https://github.com/jruby/jruby• https://www.jruby.org
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