I haven't played with non-blocking socket connects much, so I took this problem as a trial run. Note that Net::Ping in tcp mode just does a connect, nothing special, so I thought I'd try a simple non-blocking IO::Socket::INET and use IO::Select to keep track of outstanding connect attempts. Linux will show completion of a non-blocking connect by indicating "write ready" in select (see man 2 connect).

I don't have a decent enough setup for testing this since I don't have 1000 machines, but it does run on what I can fake up on my two ArchLinux machine configuration.

Plug in your own ips. Double check the number of open files allowed on your system (ulimit -a) and make $max somewhat smaller than that. It's 1024 by default on my system but it is changable.

All the connects are done in parallel, and I can get it to run in under 4 seconds on my (very) kludged up test system, I'm hoping I can get results from "themonk" and any other interested monks.

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1135109

use IO::Socket;
use IO::Select;
use strict;
use warnings;

my @ips = map "192.168.0.$_", 1..11; # your IPs here
my $port = 80; # your port here
my $max = 1000; # somewhat smaller than max "open files"

my %handles;
my $n = 0;
my $sel = IO::Select->new;

while( @ips or $sel->count )
  {
  if( @ips and $sel->count < $max )
    {   
    my $ip = shift @ips;
    my $fh = IO::Socket::INET->new(PeerAddr => "$ip:$port",
      Proto => 'tcp', Blocking => 0,);
    $handles{$fh} = "$ip\t\t" . ++$n; 
    $sel->add($fh);
    }   
  elsif( @ips ? $sel->count >= $max : $sel->count )
    {   
    for my $fh ( $sel->can_write )
      {   
      print $fh->connected ? '   ' : 'not', " alive  $handles{$fh}\n";
      $sel->remove($fh);
      delete $handles{$fh};
      }   
    }   
  }
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