Re: [squid-users] Number of helpers

On 18/10/11 05:33, Emmanuel Lacour wrote:
>
> Dear squid users,
>
> - how do you know how many authentications helpers you need (I suppose
> that I need less than the maximum number of simultaneous proxy
> connexions)?

Experimentation if you don't already have Squid running. Or the info and
authenticator management reports if you do. It is related to the rate of
requests per second. Complicated by a lot of things that make it a bit
unpredictable.

If you already have Squid running without auth look at requests per
minute on the "info" manager report. Then take a guess based on that.
  squidclient mgr:info

Once you have auth running find the appropriate authenticators manager
report and look at the usage on each helper. The first one should be
kept 'hot' with most requests trailing down to ideally a few spare ones
at the end with 0 requests handled even during peak load. If your last
ones show many requests you need to increase the helper count. If most
show no requests handled at all, you can probably reduce.
  squidclient mgr:menu

> - what happens if there is not enough (authentication failed, slowness,
> ...)?

Slowdown on peak or bursts of traffic. And if the queued lookups hits
twice as may queued requests as helpers available to service them Squid
restarts. Resetting all connections.

Also, if you have too many helpers and large memory usage a reconfigure
can crash Squid with OOM errors.

So ... high, but not too high, and tune downwards if you need.

Amos

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