I don't have a strong use-case for JRuby in this particular case, so I'll just continue to use YARV. There are some Java libraries I've been tempted to use, but it's not crucial at this point.
It's not implementing message passing that's the problem, it's the shared state, multi-threaded model in general. It's too easy to trip up, so I prefer fork() and message-passing. I am less worried about my own code, but what future maintainers who have less experience in concurrent programming will have to deal with.
It's just a framework for a pool of workers that hang off an MQ, so fork() also provides some extra resiliency in the event that something bad happens.
There's nothing stopping you from running multiple JRuby instances, just as you would with any other interpreter, it's just you can't use fork() to create them. Use an external script/daemon to start up multiple processes.
It's not as memory efficient as MRI, but isn't _too_ bad unless you're on a cheapo memory constrained VPS.
It's not implementing message passing that's the problem, it's the shared state, multi-threaded model in general. It's too easy to trip up, so I prefer fork() and message-passing. I am less worried about my own code, but what future maintainers who have less experience in concurrent programming will have to deal with.
It's just a framework for a pool of workers that hang off an MQ, so fork() also provides some extra resiliency in the event that something bad happens.