I dont want to have a thread per device constantly running, especially if all its doing is sleeping.

Why not?

This would be how I would do it. Note, I've no way to test the SNMP stuff, so I've just cleaned up the code you posted elsewhere.

#! perl
use strict;
use threads;
use threads::shared;
use Net::SNMP;

sub polldevice {
    my( $running, $stop, $host, $community, $delay ) = @_;
    ++$running;

    my( $session, $error ) = Net::SNMP->session(
        Hostname => $host, Community => $community
    ) or die "session error:" . $session->error;
    do {
        my $result = $session->get_request(
            "1.3.6.1.2.1.1.2.0", "1.3.6.1.2.1.2.1.0", "1.3.6.1.2.1.1.3
+.0"
        ) or die "request error: " . $session->error;

        print "Testing ".$host."\n";
        print "Number of interfaces: ".$result->{"1.3.6.1.2.1.2.1.0"}.
+"\n";
        print "uptime: " . $result->{"1.3.6.1.2.1.1.3.0"}."\n";
        print "sysOID: " . $result->{"1.3.6.1.2.1.1.2.0"}."\n";
    } while not $stop and sleep $delay;

    $session->close;
    --$running;
}

my $stop    :shared = 0;
my $running :shared = 0;
while( <DATA> ) {
    async{ \&polldevice, $stop, split ' ' }->detach;
}

$SIG{INT} = sub{ $stop = 1 };
sleep 1 until $stop;
sleep 1 while $running;

__DATA__
192.168.1.50 public 10
192.168.1.1  public 25
192.168.1.2  public 60
192.168.1.3  public 45
192.168.1.4  public 12
192.168.1.5  public 59
192.168.1.6  public 01
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