my @files = @ARGV;
my $NUM_CPUS = 4; # or whatever
my $jobs = Thread::Queue->new(@files);

# We use undef as "end of jobs" marker
$jobs->enqueue( undef ) for $NUM_CPUS;

my @threads = map {
    threads->create(\&process);
} 1..$NUM_CPUS;

sub process {
    while( my $file = $jobs->dequeue ) {
        validate_the_file($file,$readOnlySchema);
    };
};

$_->join for @threads;