From: thefed <fedzor@...>
Date: 2008-01-01T02:56:39+09:00
Subject: Re: Why not call Thread.join?


On Dec 31, 2007, at 11:15 AM, Robert Klemme wrote:

> On 31.12.2007 17:02, thefed wrote:

>> OK, I understand it better. But why does each {|t| t.join} join  
>> them  all at the same time (ish), and not wait for the first one  
>> to finish  executing before joining the others?
>
> They are not joined at the same time but one after the other.

But then why doesn't this take 15 seconds? t.join is called in the  
main thread, so shouldn't the next Thread#join not get called until  
the first one finishes?

	module Enumerable
	  def each_simultaneously
	    threads = []
	    each { |e| threads >> Thread.new { yield e } }
	    return threads
	  end
	end

start_time = Time.now
[7,8,9].each_simultaneously do |e|
    sleep(5) # Simulate a long, high-latency operation
    print "Completed operation for #{e}!\n"
end
# Completed operation for 8!
# Completed operation for 7!
# Completed operation for 9!
Time.now - start_time                 # => 5.009334