JRuby 9000 released

When I last experimented with creating a standard Rails 4.2 app with the AR JDBC adapter and a database model a few weeks ago, it still didn't work. I haven't looked at things since then.

The workaround some people will suggest is "replace ActiveRecord with Sequel" but for existing projects a migration to a less standard Rails stack may not be viable.

I agree the JRuby team is doing a great job - however Rails is a big use case for any Ruby implementation, so my comment was not intended as a criticism, more in the line of a bug report and something it would be nice to have working now the new JRuby release is out the door.

Considering threading is the main selling point, one of the commonest patterns of regexp use being completely and dangerously broken with them would have seemed like something of a showstopper.

  def f
    p $~ # => nil
    "123" =~ /\w+/
    p $~ # => #<MatchData "123">
  end

  p $~ # => nil
  "abc" =~ /\w+/
  p $~ # => #<MatchData "abc">

  f

  p $~ # => #<MatchData "abc">

I'll admit to encountering weird "er, why is that randomly nil" errors quite regularly with JRuby when load testing webservers, which, er, I've never reported. It's never been obvious where the fault was, really. And it always seemed unlikely to be your fault, tsk ;)

> It's better to avoid using closure state if you know it's going to be called across threads

Yeah. In this case it was a hash of name -> lambda pairs which boiled down to variations on:

    ->(obj) do
      case obj.bla
        when /foo(.*)/ then "FOO_#{$1.upcase}"
        when /bla(.*)/ then $1
      end
    end

Do I understand things right, or am I wrong here?

I guess the question is where the regexp special vars are scoped to though, I see how that's not entirely clear.

https://vimeo.com/114187541

Edit: The JNR stuff is covered around 42 minutes in.

It'll prevent running it on the current Google App Engine Java Runtime.

It won't, AFAICT, prevent running it in a Google App Engine Managed VM, which is an option on today's Google App Engine.

Any particular reason why? (I'm just curious, I do absolutely nothing with ruby)

I know this is small consolation, but everything in the JRuby ecosystem is continuing to improve every day. When there's specific reproducible cases where we're slower, we take them very seriously.

We continue to try to improve startup performance, and hopefully over the next year we can close the gap a bit more.

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.