Asynchronous system calls are easy using threads::async.

use threads;

my @threads;
push @threads, async{ 
   print `perl -e "
        sleep 2 * 10 - $_; 
        print qq[job $_ completes]; " ` 
} for 1 .. 10;
$_->join for @threads;
__END__
job 10 completes
job 9 completes
job 8 completes
job 7 completes
job 6 completes
job 5 completes
job 4 completes
job 3 completes
job 2 completes
job 1 completes
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