From: Daniel Merk <daniel.merk.rubytalk@...>
Date: 2008-08-20T00:22:44+09:00
Subject: Newly created thread blocks all others in Ruby 1.8.7 patchlevel 72 on Cygwin

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Hello together,

I am using the following Ruby version:

   ruby 1.8.7 (2008-08-11 patchlevel 72) [i386-cygwin]

I have problems with threads now that did not occur in Ruby 1.8.6. I execute
the following code (derived from an
example in the Ruby core documentation):


    require 'thread'

    count1 = count2 = 0
    puts "starting thread a"
    a = Thread.new do
          loop { count1 += 1 }
        end
    a.priority = -1

    puts "starting thread b"
    b = Thread.new do
          loop { count2 += 1 }
        end
    b.priority = -2
    sleep 1   #=> 1
    Thread.critical = 1

    puts "count1: #{count1}"
    puts "count2: #{count2}"


This code never starts thread b. It seems that thread a blocks all
other threads once it runs (though its priority is lowered), even the
main thread.
If I put a sleep command into the thread a loop, thread b starts, but
the problem remains, since then thread b blocks all others from
running.

The Ruby 1.8.7 release notes speak of a change in the mutex
implementation in C. Could that be a problem?

Thanks for any help
Daniel

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