my %kids;
sub REAP {
    while((my $deceased = waitpid(-1, WNOHANG)) != -1) {
         delete $kids{$deceased};
    }       
    $SIG{CHLD} = \&REAP;
}
$SIG{CHLD} = \&REAP;

while ($new_sock = $sock->accept()) {

    if(my $kid = fork) {
        $kids{$kid} = 1; 
        # parent closes the client since
        # it is not needed
        close $new_sock;
    } else {
        die unless defined $kid;  # if fork failed
        # the kid's work
        # ...
        exit;
    }
}