Same as a regular task, but the immediate prerequisites are done in parallel using Ruby threads.

Methods
Public Instance methods
invoke_prerequisites()
     # File lib/rake.rb, line 556
556:     def invoke_prerequisites
557:       threads = @prerequisites.collect { |p|
558:         Thread.new(p) { |r| Task[r].invoke }
559:       }
560:       threads.each { |t| t.join }
561:     end