I don't like JVM: I hate the mandatory 2-second startup time and "warming up" time. And the standard set of libraries doesn't look particularly well engineered to me (comparing Java SE to .NET or Python's libs). Also, despite being enterprise-tested and good at memory management with it's "best in class" generational GC, Java programs continue to be memory hogs, based on personal experience.
But you can't beat a nice piece of software (JRuby) and the huge ecosystem of high quality Java libraries. Moreover, JRuby guys are awesome at listening and talking to their community. You can go and ask any question about JRuby internals on #jruby - someone will always be there.
I am definitely considering switching my projects to JRuby, just need to find time.
I hate the mandatory 2-second startup time and "warming up" time.
I got about 0.45s for a basic Java app on first start, then 0.2s subsequently. For a JRuby one-liner, I get 0.618s consistently (no first start to count). So while JRuby appears to add about 0.4s to startup, it's no 2 seconds.
But you can't beat a nice piece of software (JRuby) and the huge ecosystem of high quality Java libraries. Moreover, JRuby guys are awesome at listening and talking to their community. You can go and ask any question about JRuby internals on #jruby - someone will always be there.
I am definitely considering switching my projects to JRuby, just need to find time.