From: Michael Malone <michael.malone@...>
Date: 2009-03-09T09:25:06+09:00
Subject: 1.9.x Thread problem

Hi All,

Here's a tricky one for you:

require 'thread'

THREADS = 10
WASTE = 10000

pid = fork() do
   queue = Queue.new
   THREADS.times do |i|
      queue << Thread.new do
         # wasting actual cpu time, rather than sleeping
         Thread.current[:index] = i
         n = rand(WASTE)
         Thread.current[:n] = n
         d = 1.0 + 1/n.to_f
         e = 1.0
         n.times { e = e * d }
      end
   end

   THREADS.times do
      th = queue.pop
      puts "Joining thread #{th[:index]}, n=#{th[:n]}"
      th.join()
   end

end

Process.wait(pid)

If I run this using ruby 1.8.7 (2008-08-11 patchlevel 72) [i486-linux] I 
get the output I would expect:
Joining thread 0, n=8767
Joining thread 1, n=2401
Joining thread 2, n=514
Joining thread 3, n=5227
Joining thread 4, n=658
Joining thread 5, n=8618
Joining thread 6, n=2356
Joining thread 7, n=7431
Joining thread 8, n=8426
Joining thread 9, n=588

If I run this using either ruby 1.9.1p0 (2009-01-30 revision 21907) 
[i686-linux] or ruby 1.9.2dev (2009-03-05 trunk 22769) [i686-linux] I 
get results I would not expect:
Joining thread , n=
Joining thread 1, n=1131
Joining thread 2, n=8233
Joining thread 3, n=8696
Joining thread 4, n=7684
Joining thread 5, n=286
Joining thread 6, n=6618
Joining thread 7, n=2814
Joining thread 8, n=5862
Joining thread 9, n=6307

My best guess is that something similar to the fix for this bug 
http://redmine.ruby-lang.org/issues/show/657 is happening, but elsewhere 
in the code.  Does anyone have any ideas?

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