However I am still seeing a LONG period of hanging for some hosts that is happening AFTER the timeout is reached, and when the subroutine is trying to CLOSE the pipe.

Why is this? By code is below

The piped open to a command returns that's processes PID.

You could use that to be unpolite and then close the pipe:

    if( my $pid = open my $pipe, "traceroute -I -n $hostname |" ) {
        while(1) {
            last if ...
        }
        kill 2, $pid;
        close $pipe;
    }
[download]

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}