Scaling Ruby with JRuby
summary
JRuby 9.4 runs Ruby 3.1 on the JVM (Java 17) and gives real native parallel threads so a single JRuby process uses many cores with Puma and MySQL rather than dozens of CRuby workers. Benchmarks show JRuby reaching peak after ~6 iterations of 2000 requests, delivering roughly 2x throughput over CRuby on a full Rails stack, with memory tuned to ~900MB–1GB versus CRuby’s ~1.5GB with 16 workers. One migration cuts 40 extra‑large instances to 10, a 75% cost reduction. JRuby 9.4 Java 17
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chapters (11)
- 0:00Introduction
- 2:06What is JRuby
- 3:52Ruby 9.4 compatibility
- 4:56Run Ruby on JVM
- 8:50JRuby and Rails scaling
- 12:25Performance and benchmarking
- 17:00Memory and warm-up
- 21:12Rails scaling benchmarks
- 25:10Cost savings with JRuby
- 26:33JRuby future features
- 28:02Q&A
