From: Norman Makoto Su <normsu@...>
Date: 2002-03-29T17:04:31+09:00
Subject: Mutex problems

OK, I know recently I've been posting too many messages to this mailing list, so
please bear with a ruby newbie (whoa, it rhymes) =)

I just tried the pickaxe book's mutex example (slightly modified):

require 'thread'
mutex = Mutex.new
Thread.abort_on_exception = true
count1 = count2 = 0
difference = 0
counter = Thread.new do
  loop do
    mutex.synchronize do
      count1 += 1
      count2 += 2
    end
  end
end

spy = Thread.new do
  loop do
    mutex.synchronize do
      difference += (count1 - count2).abs
    end
  end
end

sleep 1
mutex.lock
puts count1
puts count2
puts difference

And, I get the following result:

10014
20028
67795929

Now, given my small understanding of how mutex's are supposed to work...
difference should be 0 and the count vars should be equal, right?  Typing
ruby --version on my linux 2.0.34 system gives me:

ruby 1.6.7 (2002-03-01) [i686-linux-libc1]

Any help would be greatly appreciated!  I have looked at old mailing lists and
have noticed there are some problems with threads in window versions, but since
this is in unix, I thought it should work fine.  Thanks,

--
Norman Makoto Su