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From Yann Ylavic <ylavic....@gmail.com>
Subject Re: Ideas from ApacheCon
Date Thu, 01 Jun 2017 22:15:46 GMT
On Thu, Jun 1, 2017 at 10:48 PM, Jim Riggs <apache-lists@riggs.me> wrote:
>> On 1 Jun 2017, at 15:25, Yann Ylavic <ylavic.dev@gmail.com> wrote:
>>
>> On Thu, Jun 1, 2017 at 10:22 PM, Yann Ylavic <ylavic.dev@gmail.com>
>> wrote:
>>> On Thu, Jun 1, 2017 at 7:29 PM, Jim Riggs <apache-lists@riggs.me>
>>> wrote:
>>>>> On 1 Jun 2017, at 07:55, Jim Jagielski <jim@jaguNET.com>
>>>>> wrote: 2. I understand the logic behind creating the arrays,
>>>>> but doesn't this increase the overhead. We go thru the full
>>>>> list of workers one time, and then go thru the list of avail
>>>>> works and spares right after that. Assume that all workers
>>>>> are available; doesn't it mean we go thru that last 2x?
>>> []
>>>>
>>>> The only way I can think of to avoid this without going back
>>>> to duplicating code across lbmethods, which I would argue is
>>>> worse, is to maybe have the lbmethod provide a callback
>>>> function and context pointer to
>>>> ap_proxy_balancer_usable_workers() that gets called during the
>>>> loop iteration to pick the best member in flight.
>>>
>>> Couldn't a simple 'best' for ap_proxy_balancer_usable_workers()
>>> make it return a single entry?
>>
>> ... a simple 'best' *flag* (as argument) ...
>
> I'm not sure I follow what this flag would be. The lbmethod would
> somehow have to tell ap_proxy_balancer_usable_workers() how to pick
> the best worker (e.g. by comparing the number of bytes sent or the
> number of requests processed). I'm not sure how that information
> could be passed as a flag unless we baked the behavior of byrequests,
> bybusyness, and bytraffic into ap_proxy_balancer_usable_workers().
> But then how would we allow for plugging in additional lbmethods?

Oh right, nevermind, I thought per lbmethod logic was already there.
After a better look into it, a callback (and its baton) with that
logic looks straightforward, though.

Regarding:
 worker = &APR_ARRAY_IDX(balancer->workers, i, proxy_worker *);
I don't see why worker needs to be a 'proxy_worker**' ('*worker' is
never updated IIUC).

Looks like:
 proxy_worker *worker = APR_ARRAY_IDX(balancer->workers, i, proxy_worker *);
would be fine and allow using 'worker->xxx' instead of
'(*worker)->xxx' all over the place...


Regards,
Yann.

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