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From jean-frederic clere <jfcl...@gmail.com>
Subject Re: Missing proxy_balancer feature
Date Thu, 01 Jul 2010 06:46:46 GMT
On 07/01/2010 03:14 AM, Daniel Ruggeri wrote:
> 
> On 6/30/2010 7:34 AM, jean-frederic clere wrote:
>> On 06/30/2010 04:17 AM, William A. Rowe Jr. wrote:
>>   
>>> Yet again, in class another student pointed out that the
>>> Enabled/Disabled
>>> choice in mod_proxy_balancer totally ignores the concept of quiescing,
>>> where we are taking a server offline, but continuing to serve those
>>> requests targeted by session to that server.  Once the number of
>>> sessions
>>> settles on something quite low, the user then takes that server offline
>>> entirely and the remaining users are subjected to 'expired session'
>>> results.
>>>
>>> A boolean Enabled/Disabled flag doesn't address this need.
>>>
>>> Does anyone feel like working on this feature, since those I had
>>> previously approached didn't have all that much interest, or got
>>> busy with other things?
>>>
>>>
>>>      
>> There are several things that requires improvements:
>> 1 - The default load balancing logic doesn't work well when you restart
>> a back-end node.
>>
>> ...
>>
>> Cheers
>>
>> Jean-Frederic
>>
>>    
> Jean-Frederic;
>    Can you elaborate more on point 1? I have had issues where a back end
> application was not ready during a restart and throws a 503 to Apache.
> Since this is a perfectly valid response to the proxied request, Apache
> happily sends it along to the user. I wrote a bug (48939) and submitted
> a patch that creates a configuration directive to help mitigate this
> issue which is the most significant issue I have come across during a
> simple back end restart. The patch is currently proposed in STATUS, but
> has not received votes to go forward (or stay in STATUS).

That is something different the algorithm used doesn't work correctly
when you have long lasting sessions and the load for the past is not
forgotten... Basically to much load is going to the returning back-end.

Your patch is just a work-around to the problem that httpd doesn't know
that the back-end shouldn't be used at that time.

Cheers

Jean-Frederic

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