JRuby

The code that fails relies on thread#alive?

Have you done anything to this since 1.2.0?

Found an error:

uninitialized class variable @@running in #<Class:01x1978611>

The variable is initialized. Here is the code:

http://gist.github.com/119648

The error occurs in line 32.

Here is a minimal example that fails:

module ActiveMessaging
  class Gateway
    @@running = true
    class <<self
      def start
        Thread.start do
          begin
            puts @@running
          rescue Object
            puts $!.message
            puts $!.backtrace.join("\n")
          end
        end
      end
    end
  end
end

ActiveMessaging::Gateway.start
sleep 2

Hmm, ok...this is another problem with class variables. I hate class variables.

I think we need to fix this before 1.3 final.

I've got a test case that illustrates this pretty succinctly:

require 'test/unit'

class TestClassVars < Test::Unit::TestCase
  def test_thread_in_eigenclass
    result = Class.new do
      @@running = true
      class << self
        Thread.new do
          @@running
        end.join
      end
    end

    assert_equal true, result
  end

  def test_thread_in_method_in_eigenclass
    result = Class.new do
      @@running = true
      class << self
        def go
          Thread.new do
            p @@running
          end.join
        end
      end
    end.go

    assert_equal true, result
  end
end

It seems like it's something to do with the thread; any other block in there works fine. Perhaps the thread's block is getting mutilated in some way that damages cvar lookup?

Fixed! The problem was that when we duplicated the scope for a thread (to fix backref/lastline scoping) we did not also copy the previousCRefScope, which meant that class vars were not being looked up correctly at the top level of a Thread's block. I also added tests for it in test_cvar_in_weird_scopes.

Thanks!