[squid-users] squid workers question

[Alex Rousskov]

On 03/09/2017 09:19 AM, Matus UHLAR - fantomas wrote:
> On 09.03.17 09:07, Alex Rousskov wrote:
>> Both rock and AUFS stores support large objects so there is no
>> requirement to split storage based on object sizes. Each store has
>> various pros and cons, but lack of large object support is not one of
>> the distinguishing characteristics.

> I thought the cons of *ufs/disks is ineffective storage of small files,
> while rock is ineffective with big files...

While this assertion is true in some environments for some definitions
of "ineffective", I would avoid such generalizations: If your goal is to
optimize overall Squid performance, then there are a lot more factors
that you should take into account before deciding whether it is is a
good idea to split cache_dirs based on object sizes.


>>> - do I get it right that kid1 is the Master, kid2 is the disker for rock
>>>   store and kid3 is the single worker process?
>>
>> In SMP mode (which, BTW, AUFS store does not support),
> 
> could it crash squid instead of complaining?

In SMP mode, SMP-unaware stores crash, corrupt, and/or duplicate
responses, depending on your luck and squid.conf. They do not complain.


>> Master is not a
>> kid (it is a parent of all kids), the first N kids are workers, the next
>> D kids are diskers, and the last kid is Coordinator. Please see the
>> following wiki section for more details.
>>   http://wiki.squid-cache.org/Features/SmpScale#Terminology



>> Yes, "1" is the default value for the workers directive.

> and this is why I wonder we have three kids, both when "workers"
> commented out and when set to 1.

In my earlier paragraph, N is the value of the workers directive. There
are other kids (D diskers and one Coordinator). D is the number of rock
cache_dirs. Both workers and diskers need shared memory and IPC.

If you want to turn off SMP while using rock store, start Squid with -N.
When started with -N, there will be a single process playing all four
roles (master, worker, disker, and Coordinator).


HTH,

Alex.