NAME

  forkoff

SYNOPSIS

  brain-dead simple parallel processing for ruby

URI

  http://rubyforge.org/projects/codeforpeople

INSTALL

  gem install forkoff

DESCRIPTION

  forkoff works for any enumerable object, iterating a code block to run in a
  child process and collecting the results.  forkoff can limit the number of
  child processes which is, by default, 8.

SAMPLES

  <========< samples/a.rb >========>

  ~ > cat samples/a.rb

    #
    # forkoff makes it trivial to do parallel processing with ruby, the following
    # prints out each word in a separate process
    #
    
      require 'forkoff'
    
      %w( hey you ).forkoff!{|word| puts "#{ word } from #{ Process.pid }"}

  ~ > ruby samples/a.rb

    hey from 3239
    you from 3240


  <========< samples/b.rb >========>

  ~ > cat samples/b.rb

    #
    # for example, this takes only 1 second or so to complete
    #
    
      require 'forkoff'
    
      a = Time.now.to_f
    
      results =
        (0..7).forkoff do |i|
    
          sleep 1
    
          i ** 2
    
        end
    
      b = Time.now.to_f
    
      elapsed = b - a
    
      puts "elapsed: #{ elapsed }"
      puts "results: #{ results.inspect }"

  ~ > ruby samples/b.rb

    elapsed: 1.07044386863708
    results: [0, 1, 4, 9, 16, 25, 36, 49]


  <========< samples/c.rb >========>

  ~ > cat samples/c.rb

    #
    # forkoff does *NOT* spawn processes in batches, waiting for each batch to
    # complete.  rather, it keeps a certain number of processes busy until all
    # results have been gathered.  in otherwords the following will ensure that 2
    # processes are running at all times, until the list is complete. note that
    # the following will take about 2 seconds to run (2 sets of 2 @ 1 second).
    #
    
    require 'forkoff'
    
    pid = Process.pid
    
    a = Time.now.to_f
    
    pstrees =
      %w( a b c d ).forkoff! :processes => 2 do |letter|
        sleep 1
        { letter => ` pstree -l 2 #{ pid } ` }
      end
    
    
    b = Time.now.to_f
    
    puts
    puts "pid: #{ pid }"
    puts "elapsed: #{ b - a }"
    puts
    
    require 'yaml'
    
    pstrees.each do |pstree|
      y pstree
    end

  ~ > ruby samples/c.rb

    
    pid: 3254
    elapsed: 2.12998485565186
    
    --- 
    a: |
      -+- 03254 ahoward ruby -Ilib samples/c.rb
       |-+- 03255 ahoward ruby -Ilib samples/c.rb
       \-+- 03256 ahoward ruby -Ilib samples/c.rb
    
    --- 
    b: |
      -+- 03254 ahoward ruby -Ilib samples/c.rb
       |-+- 03255 ahoward ruby -Ilib samples/c.rb
       \-+- 03256 ahoward ruby -Ilib samples/c.rb
    
    --- 
    c: |
      -+- 03254 ahoward ruby -Ilib samples/c.rb
       |-+- 03261 ahoward (ruby)
       \-+- 03262 ahoward ruby -Ilib samples/c.rb
    
    --- 
    d: |
      -+- 03254 ahoward ruby -Ilib samples/c.rb
       |-+- 03261 ahoward ruby -Ilib samples/c.rb
       \-+- 03262 ahoward ruby -Ilib samples/c.rb