use MCE::Flow max_workers => 8;

   my $file1 = "/path/to/file1.txt";
   my $file2 = "/path/to/file2.txt";

   unlink $file1 if -e $file1;
   unlink $file2 if -e $file2;

   mce_flow sub {
      my $wid = MCE->wid;

      if (MCE->wid % 2 == 0) {
         MCE->sendto("file:$file1", "sunny day from $wid\n");
      } else {
         MCE->sendto("file:$file2", "raining day from $wid\n");
      }
   };