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;
}

##</code><code>##

pinging 6 IPs...
debug mping
my pid is 13884
7 file descriptors:
0 1 2 3 4 5 6

spawned ping, pid 13901, fileno 6
spawned ping, pid 13902, fileno 9
spawned ping, pid 13903, fileno 12
spawned ping, pid 13904, fileno 15
spawned ping, pid 13905, fileno 18
spawned ping, pid 13906, fileno 21
spawned 6 ping commands
starting read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
end read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
starting read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
end read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
starting read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
end read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
starting read loop 4
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
done reading from pid 13906 fd `21`, closing
close 13906 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13905 fd `18`, closing
close 13905 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13904 fd `15`, closing
close 13904 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13903 fd `12`, closing
close 13903 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13902 fd `9`, closing
close 13902 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13901 fd `6`, closing
close 13901 status: fd: ``; rv: `1`; $!: ``; $?: 0
end read loop 4
there are 0 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 10 11 13 14 16 17 19 20 22 23

pinging 6 IPs...
debug mping
my pid is 13884
19 file descriptors:
0 1 2 3 4 5 6 7 8 10 11 13 14 16 17 19 20 22 23

spawned ping, pid 13920, fileno 6
spawned ping, pid 13921, fileno 15
spawned ping, pid 13922, fileno 24
spawned ping, pid 13923, fileno 27
spawned ping, pid 13924, fileno 30
spawned ping, pid 13925, fileno 33
spawned 6 ping commands
starting read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
end read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
starting read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
end read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
starting read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
end read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
starting read loop 4
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36
done reading from pid 13925 fd `33`, closing
close 13925 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13924 fd `30`, closing
close 13924 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13923 fd `27`, closing
close 13923 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13922 fd `24`, closing
close 13922 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13921 fd `15`, closing
close 13921 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13920 fd `6`, closing
close 13920 status: fd: ``; rv: `1`; $!: ``; $?: 0
end read loop 4
there are 0 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 25 26 28 29 31 32 34
35

pinging 6 IPs...
debug mping
my pid is 13884
31 file descriptors:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 25 26 28 29 31 32 34
35

spawned ping, pid 13936, fileno 6
spawned ping, pid 13937, fileno 27
spawned ping, pid 13938, fileno 36
spawned ping, pid 13939, fileno 39
spawned ping, pid 13940, fileno 42
spawned ping, pid 13941, fileno 45
spawned 6 ping commands
starting read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
end read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
starting read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
end read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
starting read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
end read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
starting read loop 4
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
done reading from pid 13941 fd `45`, closing
close 13941 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13940 fd `42`, closing
close 13940 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13939 fd `39`, closing
close 13939 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13938 fd `36`, closing
close 13938 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13937 fd `27`, closing
close 13937 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13936 fd `6`, closing
close 13936 status: fd: ``; rv: `1`; $!: ``; $?: 0
end read loop 4
there are 0 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 28 29 30
31 32 33 34 35 37 38 40 41 43 44 46 47

pinging 6 IPs...
debug mping
my pid is 13884
43 file descriptors:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 28 29 30
31 32 33 34 35 37 38 40 41 43 44 46 47

spawned ping, pid 13952, fileno 6
spawned ping, pid 13953, fileno 39
spawned ping, pid 13954, fileno 48
spawned ping, pid 13955, fileno 51
spawned ping, pid 13956, fileno 54
spawned ping, pid 13957, fileno 57
spawned 6 ping commands
starting read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
end read loop 1
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
starting read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
end read loop 2
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
starting read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
end read loop 3
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
starting read loop 4
there are 6 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
 57 58 59 60
done reading from pid 13957 fd `57`, closing
close 13957 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13956 fd `54`, closing
close 13956 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13955 fd `51`, closing
close 13955 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13954 fd `48`, closing
close 13954 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13953 fd `39`, closing
close 13953 status: fd: ``; rv: `1`; $!: ``; $?: 0
done reading from pid 13952 fd `6`, closing
close 13952 status: fd: ``; rv: `1`; $!: ``; $?: 0
end read loop 4
there are 0 pings active
fd status from /proc/13884/fd:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 40 41 42 43 44 45 46 47 49 50 52 53 55 56 58 59

pinging 6 IPs...
debug mping
my pid is 13884
55 file descriptors:
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 40 41 42 43 44 45 46 47 49 50 52 53 55 56 58 59

.....etc.....