Depending on how you are deploying the ruby app.

As far as I know, Passenger Enterprise and Puma are the only multi-platform ruby rack app servers that support multi-threaded concurrent request dispatch. There may be other jruby/java-only deployment scenarios that support concurrent request dispatch.

Without concurrent request dispatch, jruby's hypothetical greater thread parallelism is unlikely to effect requests-per-second benchmarks. Also, the benchmarking test would have to be willing to issue requests concurrently!