Specifies the maximum number of StoreID helper processes that Squid
may spawn (numberofchildren) and several related options. Using
too few of these helper processes (a.k.a. "helpers") creates request
queues. Using too many helpers wastes your system resources.
Usage: numberofchildren [option]...
The startup= and idle= options allow some measure of skew in your
tuning.
startup=
Sets a minimum of how many processes are to be spawned when Squid
starts or reconfigures. When set to zero the first request will
cause spawning of the first child process to handle it.
Starting too few will cause an initial slowdown in traffic as Squid
attempts to simultaneously spawn enough processes to cope.
idle=
Sets a minimum of how many processes Squid is to try and keep available
at all times. When traffic begins to rise above what the existing
processes can handle this many more will be spawned up to the maximum
configured. A minimum setting of 1 is required.
concurrency=
The number of requests each storeID helper can handle in
parallel. Defaults to 0 which indicates the helper
is a old-style single threaded program.
When this directive is set to a value >= 1 then the protocol
used to communicate with the helper is modified to include
an ID in front of the request/response. The ID from the request
must be echoed back with the response to that request.
queue-size=N
Sets the maximum number of queued requests to N. A request is queued
when no existing child can accept it due to concurrency limit and no
new child can be started due to numberofchildren limit. The default
maximum is 2*numberofchildren. If the queued requests exceed queue
size and redirector_bypass configuration option is set, then
redirector is bypassed. Otherwise, Squid is allowed to temporarily
exceed the configured maximum, marking the affected helper as
"overloaded". If the helper overload lasts more than 3 minutes, the
action prescribed by the on-persistent-overload option applies.
on-persistent-overload=action
Specifies Squid reaction to a new helper request arriving when the helper
has been overloaded for more that 3 minutes already. The number of queued
requests determines whether the helper is overloaded (see the queue-size
option).
Two actions are supported:
die Squid worker quits. This is the default behavior.
ERR Squid treats the helper request as if it was
immediately submitted, and the helper immediately
replied with an ERR response. This action has no effect
on the already queued and in-progress helper requests.