Re: 1.9.x Thread problem


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=


It hasn't been defined which thread, the created child thread
or the creating parent thread, runs first at thread creation.
In 1.8, the child runs first by chance.



I have read and re-read this about 10 times now and this comment makes
it appear that the contract for Thread.new {block}, where the block is
run exclusively in the newly created thread, is violated.
Can you then explain why it runs consistently like this or a way in
which I can guarantee I am running in the first created child thread?
I would have expected to be inside of the child thread because the
code setting up the :index is inside the block passed to
Thread.new(). And I only put the created child Thread instances in
the Queue, so I should _only_ get child Thread instances when I call
Queue#pop.
require 'thread'
THREADS = 10

parent_id = Thread.current.object_id

queue = Queue.new
THREADS.times do |i|
queue << Thread.new do
th = Thread.current
th[:index] = i
raise "Running inside parent" if th.object_id == parent_id
sleep(2)
end
end

THREADS.times do
th = queue.pop
raise "Running inside parent" if th.object_id == parent_id
puts "Joining thread #{th[:index]}"
th.join()
end

I have simplified and changed things. I am quite certain that the
parent thread is not being joined or indeed added to the queue as no
exceptions are raised (unless this is a bad test) and I still get the
same (strange) output. Any other ideas?


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