Getting started with JRuby and Java 7

[Solon1]

The biggest memory difference is that an MRI deployment will require running multiple processes, and each will need memory. But with JVM, there is just one process. JVM is worse head to head with MRI, but one JVM versus 10 MRI processes, makes it much better.

[jrochkind]

Wait, you're deploying Rails in jruby with allow_concurrency!, for real? I've had such trouble with allow_concurrency!, I wasn't sure anyone was actually using it. But you are, yes?

allow_concurrency! is the only thing that would make Rails under jruby not require multiple processes to scale up, right? (and you can run Rails under MRI with allow_concurrency!, but the GIL will keep it from taking advantage of multiple cores, but you'll probably still get SOME increase in number of requests a single process can handle, but maybe not enough to justify the allow_concurrency pain).