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From Brian Akins <>
Subject Re: Working on some load balancing methods
Date Tue, 11 Jan 2005 13:25:24 GMT
Mladen Turk wrote:
> Sure, the general idea was to allow different lb methods.
> I've started to collect the transferred for various
> protocols to be able to do a traffic balancing.

So, there will be an API to allow developers to develop load balancers 
without having to muck with the proxy code?  If so, yes!  If not, it 
would rule.

What we did is write our own proxy module because of limitations in the 
2.0 one.  Basically it's like this:

-There is an external programe (started like a piped log program) that 
does "active" health checking. Every x seconds it checks all the 
"origin" servers and records their status in shared memory.

-In our proxy module, it uses the information in the shared memory to 
maintain a apr_reslist of connections.  It it gets an error before 
sending data to the client (one origin server hiccup'ed, for example), 
it will apr_reslist_invalidate that connection, apr_reslist_acquire 
another and try again.  It will do this x times.

-only after x "errors" will an error actually be returned to the client.

-because of this, we could not use mod_proxy_http and use our own http 
client code.

Does this sound doable within the 2.1/2.2 proxy lb?  Or do will we have 
to continue to maintain our own proxy?  This functionality is very 
important for us.

Brian Akins
Lead Systems Engineer
CNN Internet Technologies

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