From: "Morris, Chris" <chris.morris@...>
Date: 2002-05-31T22:01:31+09:00
Subject: Threading question

Question about Ruby threading. I wrote the following routine trying to 
create a conflict between one thread deleting an element from the array
while another thread is sorting the same array (so that I could properly
test my ThreadSafeArray I just posted in another msg...) 

But it seems that Ruby allows the @a.sort! call to go uninterrupted by
other threads. My assumption then is that the granularity never gets
smaller than a single line of script. Even though a lot of C code is 
surely occurring here underneath the sort! call, Ruby allows all of that
to occur, holding up the other threads until its done. Is this a correct
assumption?

  def test_ts_array
    @a = [] 
    (1..1000000).each do @a << rand(100000) end
    threads = []
    (1..3).each do |num|
      threads << Thread.new(num) { |num|
        Thread.current["id"] = num
        (1..10).each do |i|
          if rand(2) == 1
            puts 'delete ' + num.to_s
            @a.delete_at(@a.length / 2)
          else
            puts 'begin sort ' + num.to_s
            @a.sort!         
            puts 'end sort ' + num.to_s
          end  
        end 
      }
    end
    threads.each { |t| t.join; puts t["id"]}
  end

Chris Morris
chris.morris@snelling.com