My current project is JRuby on Rails, so I wanted to inject my few cents, and also to ask what your long-term experiences with the platform were. Rake tasks ar

My current project is JRuby on Rails, so I wanted to inject my few cents, and also to ask what your long-term experiences with the platform were. Rake tasks are definitely slow; you have to wait a few seconds for them to complete, which overall sucks. A lot. If anything, this is the one thing that has pushed me to thinking about using MRI again. Nailgun is supposed to help a lot here, and since JRuby 1.4.0 was recently released, I'll be giving NG a go and seeing what the improvement is for common rake tasks. RAM hasn't been a big problem for me. The JVM does use more RAM than MRI, but it also seems to do a better job of managing it. I've never had an out-of-memory error, and the nastiest benchmarks I could throw against my code (a few hours' worth of solid requests) don't jack the JVM above around 200M of RAM, and that's with an embedded Solr server for indexing/searching. BUT... we haven't done a fully public beta yet, just the 'friends and family' version. So I could be talking out of the wrong orifice here. You get real threading, which makes setting up a job scheduler a lot easier, and lets you run a multithreaded Rails server. The performance is quite good when compared to the 1.8.7 MRI. Accessing Java classes isn't as nice as Closure/Groovy, but that's to be expected. Closure and Groovy were designed from the ground up to use Java classes as their foundation, and Ruby... wasn't. Even so, JRuby does a decent job of autoboxing most of the time with strings and arrays, and I've had only a few speedbumps when using Java classes in JRuby. Loading JARs seems to work fine with 'require' for me; what problems have you run into? What is the long-term memory use for your application like; e.g., does it grow hugely over time, or remain relatively stable after the JVM warmup? What JVM/JRuby are you using? Other than startup slowness, what other issues have been problems for you?