You don't need any modules.

#! perl -slw
use strict;

## Count the lines in all the .pl file in the CWD
my $count = 0;
for my $file ( glob '*.pl' ) {

    ## The 1, causes the command to be run in the background
    system 1, "wc -l $file"; 
    $count++;
}

print "$count processes started";
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Of course, you may want to control the number of concurrent processes, in which case P::FM or one of the others is probably a good idea.