Re: Round-Robin becomes unbalanced when a peer dies and comes back

Hm, that sounds right. You're basically having to recalculate/reconverge
your peer weightings, and thats the sensible way to do it.

Adrian

On Fri, Jun 06, 2008, Mark Nottingham wrote:
> Oh, I chopped off the last part; if people agree with that plan, I'll
> produce a patch.
>
>
> On 06/06/2008, at 11:46 AM, Mark Nottingham wrote:
>
> ><http://www.squid-cache.org/bugs/show_bug.cgi?id=2376>
> >
> >When a peer goes down and then comes back, its round-robin counters
> >aren't
> >reset, causing it to get a disproportionate amount of traffic until
> >it "catches
> >up" with the rest of the peers in the round-robin pool.
> >
> >If it was down for load-related issues, this has the effect of
> >making it more
> >likely that it will go down again, because it's temporarily handling
> >the load
> >of the entire pool.
> >
> >Normally, this isn't a concern, because the number of requests that
> >it can get
> >out-of-step is relatively small (bounded to how many requests it can
> >be given
> >before it is considered down -- is this 10 in all cases, or are
> >there corner
> >cases?), but in an accelerator case where the origin has a process-
> >based
> >request-handling model, or back-end processes are CPU-intensive, it
> >is.
> >
> >It looks like the way to fix this is to call peerClearRR from
> >neighborAlive in
> >neighbors.c. However, that just clears one peer - it's necessary to
> >clear *all*
> >peers simultaneously.
> >
> >Therefore, I sugest:
> >
> >1) calling peerClearRR from neighborAlive
> >
> >2) changing the semantics of peerClearRR to clear all neighbours at
> >once, and
> >change how it's called appropriately.
> >
> >
> >--
> >Mark Nottingham mnot_at_yahoo-inc.com
> >
> >
>
> --
> Mark Nottingham mnot_at_yahoo-inc.com
>

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