sub check_for_completed_processes
{
   my @completed;
   my @temp;
 #  print "Checking for completed procs...\n";
   while(my $running = pop @running)
   {
      if(waitpid($running -> {process_id} ,&WNOHANG))
      {
         $running -> {end_time} = timestamp();
       #  print "Finished. \n";
         push @completed, $running;
         print "Process completed: " . $running -> {process} . "\n";
         print "Started at: " . $running -> {start_time} . "\n";
         print "End time: " . $running -> {end_time} . "\n";
      }
      else
      {
         push @temp, $running;
      }
   }
   @running = @temp;
   return @completed;                                                                               
}