[pmontra]

What I read is that it's faster for long running applications (example: web apps) because the JIT can optimize the code. It should be slower for anything else, example: tests (very unfortunately).

I don't know what the edit-reload-check workflow could be with JRuby and how well it can integrate with editors (few Rubyist use IDEs, http://www.sitepoint.com/ides-rubyists-use/).

Anyway, I'm doing a bundle install with jruby on a Rails project right now. Let's see if it completes and passes the tests.

[pmontra]

I've been doing some progresses but there are a few (almost) show stoppers.

One is that startup is really slow.

rails c takes 25 second to give a prompt vs 10 on with Ruby 2.2.2 and almost 0 after spring has started. It's not something that a developer likes to work with.

Second one: still immature. The PostgreSQL adapter warns

NOTE: ActiveRecord 4.2 is not (yet) fully supported by AR-JDBC, please help us finish 4.2 support - check http://bit.ly/jruby-42 for starters

Not something I want in production.

Third one, now I'm stuck with the JDBC adapter not connecting to my developement PostgreSQL over a unix domain socket. Maybe it can't (perhaps JDBC does only TCP/IP) and I have to reconfigure PostgreSQL to accept connection to 127.0.0.1:5432. That means any other application I'm working with won't work anymore and I should reconfigure them.

Summing up all together I'm not particularly eager to keep testing JRuby. Maybe somebody will solve those problems. I'll give another try to it next July.

[cheald]

It sounds like most of your issues are with JDBC/AR-JDBC rather than JRuby itself though, no?

The startup time is annoying, though, especially in the context of TDD. I do know it's an area of active research, though. You should try launching with JRUBY_OPTS="--dev" and see if that helps, though.

[pmontra]

JRUBY_OPTS="--dev" lowered the startup time to 12 second, basically on par with MRI. Thanks! I googled you suggestion and I found https://github.com/jruby/jruby/wiki/Improving-startup-time I'll try a few suggestions that look like doing with spring does (Theine and Drip).

My other problems are with JDBC but if database drivers don't support Ruby's largest use case (Rails with ActiveRecord) probably JRuby will be negatively impacted. This is about the "ActiveRecord 4.2 is not (yet) fully supported by AR-JDBC". The other one (unix domain socket) is a minor issue but any small nuisance loses developers along the way.

[cheald]

FWIW, I've never had any luck with Theine or Drip. But --dev is good stuff - it basically turns off the JIT and invokedynamic, which are great for long-running processes but not that useful for shorter script runs or consoles. JRuby defaults to "good for long-running processes" mode, which is great for production but less useful when running short-lived tasks.

Yeah, certainly understood WRT JDBC. But, as nirvdrum pointed out elsewhere in the thread, you might look at Sequel rather than AR if you do want to do JRuby stuff and AR-JDBC is holding you back - it's well-supported and I know lots of folks use it well.

The domain sockets thing is unfortunate, but AFAIK, they just aren't supported by JDBC.

[pmontra]

I realized that PostgreSQL can listen to both the Unix domain socket and a TCP address so I've been able to run the tests. I'm stuck now with the integration tests failing because they can't run the Selenium Chrome webdriver. I opened an issue. I also have some failed tests on a model, still didn't looked at them.

I won't convert this app to Sequel only to check that it works with JRuby. Neither I'll write the next one with Sequel. If JRuby doesn't handle AR it's over for me. It's JRuby that must be compatible with MRI (the reference implementation of the language), not the other way around. That until the majority of rubyists use JRuby as default. It's too risky.