[squid-users] Originserver load balancing and health checks in Squid reverse proxy mode

[Amos Jeffries]

On 10/02/21 9:59 am, Alex Rousskov wrote:
> On 2/9/21 11:35 AM, Chris wrote:
>> This is what I'm seeing in peer_select in cache_log with 44,3 debug
>> options:
> 
> Add (at least) "15,3" to your debug_options and then look for
> getWeightedRoundRobinParent lines. Looking at mgr:server_list Cache
> Manager page may also be useful.
> 
> 
>> Does the weighted-round-robin need some time to use those rtt values?
> 
> I am not 100% sure, but I think the answer to that question is "no".
> 

Well, only the time it takes to find out what the RTT actually is. As 
soon as RTT is known it is used.

This algorithm works like round-robin in that each selection cycle the 
peer with fewest "uses" gets selected. However, where normal round-robin 
adds "(1 * weight) uses" to a peer each time it gets selected, this 
algorithm adds "(RTT * weight) uses".

The debug lines Alex mentioned will tell you what weighted_rtt your 
proxy is using as its RTT count per use. If that shows "1", then the RTT 
is too small to calculate speed difference (math code improvements 
needed to cope with modern fast networks).

Amos