# Interesting stuff has happened to load the job queue and par
# the command line, and whatever else you want to happen.  
sub SPAWN {
    $counter++;
    if ( $cpid = fork ) {
        $tracker{$cpid} = $ref->[1];
    }
    else {
	# This can be a call like this, or
	my_sub( @_ );
	exit;
	# You can exec some external proc like
	# exec "/bin/ls -FC /var";
    }
}

my $dpid = 0;

while( @job_q ) {
    my $ref = shift @job_q;
    #--
    # Initial loop to spawn children
    #--
    if ( $counter < $num_children ) {
        &SPAWN( $ref );
    }
    else {
        do {
            sleep 5;
            $dpid = waitpid( -1, 1 );
        } until $dpid;
        last if ( $dpid == -1 );  # No children left
        printf "%s has finished, spawning next child (%d left)\n", $tracker{$dpi
d}, scalar @job_q;
        &SPAWN( $ref );
    }
}

do {    
    sleep 5;
    $dpid = waitpid( -1, 1 );
    printf("%s has finished\n", $tracker{$dpid}) if(defined( $tracker{$dpid} )
    );
} until $dpid == -1;