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Fork with spawn

Posted by Sandro Paganotti in Ruby on Rails - comments are closed

During the development of our current project we needed to handle a very long task (4 minutes). After a bit of googling i found spawn by Tom Anderson. Here’s how it works:

Spawn let you fork (or thread) a block of code by simply pass it as a parameter to a ‘spawn’ function:

  spawn do
   # very long long task
  end

what spawn do (when used with ‘fork’) is recreate an ActiveRecord Connection inside a fork method and then execute your block of code. You can also set the priority of the process being create with the option ‘nice’:

  spawn(:nice => 7) do
    # do something
  end

Finally you can wait the end or your child processes with the method Spawn::wait() (I took this example from the official readme):

  N.times do |i|
    # spawn N blocks of code
    spawn_ids[i] = spawn do
      something(i)
    end
  end
  # wait for all N blocks of code to finish running
  wait(spawn_ids)

I haven’t tried to use spawn with threads but as far as I’ve tested it with fork, it works perfectly.

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