Interesting. I cannot replicate this on my system.

I added code for handling the case when the IO::Socket fails, it will now give a message. I don't see (yet) any way now to not get output for each server:port.

#!/usr/bin/perl

# http://perlmonks.org/?node_id=1135109
# http://perlmonks.org/?node_id=11103970

use strict;
use warnings;
use IO::Socket;
use IO::Select;
use Time::HiRes qw( time );

my @ips = map "192.168.1.$_", 1..20; # your IPs here
push @ips, 'doesnotexist.com', 'doesnotexist'; # test for non existent
my $port = 22; # your port here
my $max = 1000; # somewhat smaller than max "open files"
my $timeout = 1;

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

while( @ips or $sel->count )
  {
  if( @ips and $sel->count < $max )
    {
    my $ip = shift @ips;
    if( my $fh = IO::Socket::INET->new(PeerHost => $ip, PeerPort => $p
+ort,
      Proto => 'tcp', Blocking => 0))
      {
      $handles{$fh} = ["$ip:$port", $fh, time]; 
      $sel->add($fh);
      }
    else
      {
      print "not exist  $ip:$port\n";
      }
    }
  elsif( @ips ? $sel->count >= $max : $sel->count )
    {
    my @connects;
    for my $fh ( @connects = $sel->can_write($timeout) )
      {
      print $fh->connected ? '   ' : 'not', " alive  $handles{$fh}[0]\
+n";
      $sel->remove($fh);
      delete $handles{$fh};
      }
    if( not @connects )
      {
      my $time = time - $timeout;
      for my $key ( keys %handles )
        {
        if( $handles{$key}[2] < $time )
          {
          print "not alive  $handles{$key}[0]\n";
          $sel->remove( $handles{$key}[1] );
          delete $handles{$key};
          }
        }
      }
    }
  }
[download]

One issue I'm seeing is that any server that gets to this point of the code:

if( not @connects )
[download]

Causes a 1 to 2 second delay. Looks like these are servers in DNS but not pingable.

That's the basic 'timeout' point, It should only get there if all active attempted connections have timed out (not completed a connection in the $timeout interval).

This should work the way I want. I'll rewrite it a bit to replicate how the current function works. Thanks for your help :)