sub kill_child
{
    print "Please wait, stopping child processes\n";
    kill USR1 => keys(%child_pids);
    sleep while (%child_pids);
}

sub reap_child
{
    while ( (my $child = waitpid(-1,&WNOHANG)) > 0 ) {
        delete $child_pids{$child};
    }
}