From: Wilson Bilkovich <wilsonb@...>
Date: 2005-11-09T03:52:55+09:00
Subject: Checking for race conditions with Ruby threads

I've got an untrustworthy legacy app that seems to have a nasty race
condition when a certain number of users click on a link at just the
right time.
I'm trying to write a Ruby unit test to trigger this, but I'm a bit stumped.

Here's my code:
require 'test/unit'
require 'open-uri'
class TestStream < Test::Unit::TestCase
  def test_work_unit_uniqueness
    ids = []
    threads = []
    100.times do |i|
      threads[i] = Thread.new do
        Thread.current[:appid] = URI("http://the_test_url/something").read
      end
    end
    ids = threads.collect {|t| t.join ; t[:appid]}
    assert_equal(ids, ids.uniq)
  end
end

The test URL spits back a single number, in plain text.  The idea is
to hit it 100 times, and make sure that each 'worker' thread got a
unique number.  However, it seems to me that with green threads, the
OS running on the Ruby machine will actually serialize these requests.
Do I need to switch to Linux and use 'fork', or is there another way
to handle this?

Thanks,
--Wilson.