From: Francis Cianfrocca <garbagecat10@...>
Date: 2007-02-23T01:23:16+09:00
Subject: Re: threads within a thread

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On 2/22/07, Robert Klemme <shortcutter@googlemail.com> wrote:
>
>  I would rather use EventMachine (as mentioned, would be a great
> opportunity to learn it) or a fixed number of threads like in a typical
> farmer worker scenario.  Basically you create N threads and feed them
> tasks via a queue.  A task would be to check one port on one host.  The
> advantage is that you can control concurrency and find out the optimal
> level.  Another advantage is that you save the overhead of multiple
> thread creations and destructions.



A quick, naive EM implementation of a part of this problem would be
something like the following. (NB, there are no threads being spun anywhere
here).

#-----------------------------------------------------
require 'rubygems'
require 'eventmachine'

ip_stem = "1.2.3."

start = Time.now

EventMachine.run {
        total = 0
        256.times {|n|
                [80,443,22].each {|port|
                        ip = "#{ip_stem}#{n}"
                        a = EventMachine::Protocols::TcpConnectTester.test(
ip, port )
                        count = proc {
                                total += 1
                                EventMachine.stop if total == 256 * 3
                        }
                        a.callback {
                                $>.puts "Connected #{ip}, port #{port}"
                                count.call
                        }
                        a.errback {
                                count.call
                        }
                }
        }
}

$>.puts "Time elapsed: #{Time.now - start}"
#-----------------------------------------------------

Tunings and extras not included, YMMV.

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