FreeRADIUS can't make progress under certain load

[rihad]

On 09/10/2011 11:23 PM, Arran Cudbard-Bell wrote:
>> I'm not blaming anyone. Thanks for the great software and for sharing it with us. The great thing about open source is that I can tweak it to my needs. I'm not saying this is the best way to get rid of the problem. But it may be the easiest and the quickest.
>> -
> It's a really bad way to fix the problem. You're just masking the underlying issue doing this.
>
> You need to figure out why your backend authentication system is taking more than 5 seconds to complete a request. Its that simple.
>
> I'm suggesting lowering the max thread count to reduce the number of requests running in parallel to take load of your backend system, so it starts responding before the NAS retransmits the packet.
>
> Likely there's much more that could be done to deal with high volumes of requests, but we would need to know what modules you're using with the server, and so far you've ignored all requests for this information.
We're using preprocess, rlm_perl (for AAA), acct_unique, detail, 
attr_filter.accounting_response.
> If you just want to throw new requests away once the number queued gets stupidly large, use the undocumented parameter 'max_queue_size' in the threadpool stanza.
>
> One the server has X number of pending requests, it'll start throwing new ones away, relying on the NAS' retransmit behaviour to eventually get the request processed.
Great. First I thought of tweaking max_clients to the point where it 
never triggerred under "normal" load, but started dropping new request 
(and logging the fact) whenever the box couldn't cope with the current 
load. max_queue_size may turn out to be just as useful.