We ported our Rails application to JRuby in order to do some GC comparisons yesterday. Not a ton of changes required. Mostly replacing gems with native dependencies. YAML is a bit more strict than its MRI counterpart…. but all told, thats pretty amazing! Nice job JRuby crew!
That said…. one interesting, entirely un-scientific, test case. After requesting the same URL 6 times, the VM got a lot better. 3.4s to 480ms
Completed in 3380ms (View: 2739, DB: 65) | 200 OK [http://someurl.com/people/3]
Completed in 1299ms (View: 1211, DB: 18) | 200 OK [http://someurl.com/people/3]
Completed in 1020ms (View: 949, DB: 20) | 200 OK [http://someurl.com/people/3]
Completed in 852ms (View: 732, DB: 18) | 200 OK [http://someurl.com/people/3]
Completed in 743ms (View: 628, DB: 31) | 200 OK [http://someurl.com/people/3]
Completed in 485ms (View: 374, DB: 14) | 200 OK [http://someurl.com/people/3]
It doesnt appear to be the DB caching the data. That time stayed consistent.
I didnt use any crazy runtime flags.. Just jetty, a war file, and -server….
If it was something we were memcaching, then after the 2nd request, it would have been consistent.
The amount of time spent in the view improved dramatically.
I didnt think JRuby leveraged JIT’ing yet. Anyone care to guess/explain why it was significantly better per request?
Note: It did trail off in the 300ms range with further testing...