Henrik Nordstrom-5 wrote:
>
> tis 2009-09-29 klockan 02:41 -0700 skrev tookers:
>> Hello all,
>>
>> I'm running several Squid boxes as reverse proxies, the problem i'm
>> seeing
>> is when there are a high number of connections in the region of 80,000
>> per
>> Squid at peak I'm getting 1,000's of TCP_MISS for the same URL hitting
>> the
>> back end servers, things do eventually sort themselves out. Is there any
>> way
>> to prevent such behaviour? I assumed with 'collapsed_forwarding on' it
>> would
>> only send a single request to the backend for new content?
>
> It does, but if that response is not cachable for some reason then all
> waiting clients will storm the server all at once..
>
>
> Regards
> Henrik
>
Hi Henrik,
Thanks for your reply. I'm getting TCP_MISS/200 for these particular
requests so the file exists on the back-end, Squid seems unable to store the
object in cache (quite possible due to a lack of free fd's), or possibly due
to the high traffic volume. I've increased the number of fd's (from 100k to
150k), increased cache_mem from 512MB to 768MB and enabled cache_log to
check requests during busy peaks.
Is there any way to control the 'storm' of requests? I.e. Possibly force the
object to cache (regardless of pragma:no-cache etc) or have some sort of
timer / sleeper function to allow only a small number of requests, for a
particular request, to goto the backend?
Many thanks,
tookers
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