Here's a minimal example using piped open (instead of manually creating the pipes), and IO::Select as a more convenient wrapper around the select builtin:

use IO::Select;

sub spawn_ping {
    my $addr = shift;
    open my $fh, "-|", "ping $addr -w 2 -q | sed -n '\$p'" or die $!;
    return $fh;
}

my $sel = new IO::Select();
for (1..10) {
    my $addr = 'localhost'; # or whatever
    $sel->add( spawn_ping($addr) );
}

while ( my @ready = $sel->can_read ) {
    for my $fh (@ready) {
        my $resp = <$fh>;
        if (defined $resp) {
            print STDERR $resp;  # or do with it whatever you like
        } else {
            $sel->remove($fh);
            close $fh;
        } 
    }
}
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Note that the <$fh> would (temporarily) block until a whole line is available on the respective pipe. This shouldn't be a problem in this particular case, though, as you're outputting entire lines.