In jRuby threads are native, so there should be a huge performance boost, has anybody tried it yet?
And a huge memory saving !
Notice that the project is to make it thread safe, not to make it multithreaded.
Rails thread unsafety (active record specifically) was the last block on making multi-threaded apps. JRuby, Mongrel, were multithreaded before that. Mongrel has semaphore around main rails call. I assume once you remove it with Rails 2.2 and jRuby it should be multi-threaded. What am I missing?
the only thing google turned up is AC's allow_concurrency switch has been removed (in June)