sub mping {
	my $mypid = $$;
	print "debug mping\nmy pid is $mypid\n";
	{my @ls = `ls -1 /proc/$mypid/fd`; chomp @ls;
	printf "%s file descriptors:\n", scalar @ls;
	print join " ", sort {$a <=> $b} @ls; print "\n\n"; }
	my @hosts = @{$_[0]};
	@hosts or die "no hosts to mping";
	my ($pingcmd, $pingsize, $pingnumber, $pingtimeout) = @_[1,2,3,4];
	croak "invalid mping arguments" unless $pingcmd and $pingnumber and $pingsize;
	my @pings;	my %results;

	for ($i=0;$i<=$#hosts;$i++) {
		$pings[$i][0] = $hosts[$i];
		my $pid;
		$pid = open $pings[$i][1], "-|", "$pingcmd $hosts[$i] $pingsize $pingnumber" or 
			die "Error executing $pingcmd: $!\n";;
		my $old_flags = fcntl($pings[$i][1], F_GETFL, 0) 
			or die "can't get flags: $!";
		fcntl($pings[$i][1], F_SETFL, $old_flags | O_NONBLOCK) 
			or die "can't set non blocking: $!";
		$pings[$i][2] = $pid;
		printf "spawned ping, pid $pings[$i][2], fileno %s\n", fileno $pings[$i][1];
		print "$pingcmd, $hosts[$i], $pingsize, $pingnumber failure\n" unless $pid;
	}
	printf "spawned %s ping commands\n", scalar @pings;
	my $start = time; my $j = 1;

	READ: while (@pings) {
		print "starting read loop $j\n";
		printf "there are %s pings active\n", scalar @pings;
		print "fd status from /proc/$mypid/fd:\n";
		{my @ls = `ls -1 /proc/$mypid/fd`; chomp @ls;
		print join " ", sort {$a <=> $b} @ls; print "\n"; }
		for ($i=$#pings;$i>=0;$i--) {
			my $buf;
			my $len = sysread $pings[$i][1], $buf, 580;
			if (not defined $len) { # loop
			}
			elsif ($len > 0) { # read, loop
			}
			elsif ($len == 0) {
				printf "done reading from pid $pings[$i][2] fd `%s`, closing\n", fileno $pings[$i][1];
				my $rv;
				$rv = close $pings[$i][1];
				printf "close $pings[$i][2] status: fd: `%s`; rv: `$rv`; \$!: `$!`; \$?: $?\n", 
					fileno $pings[$i][2];
				$results{$pings[$i][0]}{status} = $? >> 8;
				splice @pings, $i, 1;
			}
			else { die; }
		}
		sleep 2;
		print "end read loop $j\n";
		printf "there are %s pings active\n", scalar @pings;
		print "fd status from /proc/$mypid/fd:\n";
		{my @ls = `ls -1 /proc/$mypid/fd`; chomp @ls;
		print join " ", sort {$a <=> $b} @ls; print "\n"; }
		$j++;
	}
	return \%results;
}