I've moved this back from the deeply-nested sub-thread and quote your /msgs below for clarity.

The API response determines if the MAC is a "known" MAC. We then allow it to RADUIS auth. After RADIUS auth, the MAC is allowed into a network .

Another http service reports idle MACs based on n/w packets. I delete them from %clients forcing them to do API / RAdius Auth again.

Basically we continously allow MACs to come into the n/w , auth them in hte background and drop when no activity is seen

If I read that correctly, you retain the %client hash of MACs so that you can avoid re-authing them if they are already authed.

And you need to query another server that tracks MAC activity by inspecting packets.

And when that other server replies:"this MAC has been inactive for a while"

You delete that MAC from the %clients hash so the next time it turns up in the logs, it has to re-authorise.

If the above is a true reflection of the process, then I would suggest the following modification to the process to avoid having to constantly poll the Auth server with every known MAC.

The file reading loop remains the same:

while( <LOG> ) {
   next unless m[ACK (...)]i;
   async( \&checkMAC, $1 )->detach;
}
[download]

But the logic in checkMAC() gets modified:

sub checkMAC{
    my $mac = shift;
    
    ## If this is a known MAC & it has previously authorised successfu
+lly
    if( exists $clients{ $mac } and $clients{ $mac } ) {
        
        ## Check with the activity monitor to see if it has fallen ina
+ctive 
        my $active = get "http://activityServer/check.pl?mac=$mac";
        
        ## If is has never fallen inactive, it is known, authorised, a
+nd active
        ## and there is nothing to do
        return if $active;
        
        ## Not sure that this is really necessary, 
        ## but it might save a little resource.
        lock %clients;
        delete $clients{ $mac };
    }
    
    ## Otherwise, check http & Auth and modify status (or add) in %cli
+ents
    my $httpRes = get ...;
    my $authRes = get ...;

    lock %clients;
    $clients{ $mac } = $httpRes && $authRes ? 1 : 0;

    return.
}
[download]

This way, you'd only contact the activity server each time a MAC appears in the log, rather than constant having to poll it for every known MAC.