users@glassfish.java.net

Re: Load Balancer .. Unexpected Behaviour, Is it a BUG ?

From: Kshitiz Saxena <Kshitiz.Saxena_at_Sun.COM>
Date: Fri, 19 Dec 2008 16:38:38 +0530

Hi,

"To test failover we deleted complete application" - Can you explain
that bit more? I did not get it.

What is failover? If an instance goes down, then other healthy instances
in cluster will receive requests for ongoing sessions on failed instance
and if session data is replicated, user requests will be serviced in a
seamless manner. So, to test failover, you need to bring down one instance.

Also we assume all instances in cluster are homogeneous. From
applications perspective, this implies that all applications available
in loadbalancer xml must be deployed and available on all instances in
cluster.

Thanks,
Kshitiz

glassfish_at_javadesktop.org wrote:
> 2 Machines - 1 cluster - two instances - Application Enabled -> lb Working Fine but unexpected behavior on instance failover
>
> Test Scenario: A load tester is sending http request to lb synchronously at the rate of 5 requests per second.
> When the load starts lb creates a session with instance 1, sends requests to it, receives 200OK sends back to cleint.
> Now to test failover we deleted complete application from the server.
> Result : Failover did not happen for the ongoing session, the client started receiving 404,
> When I restarted the test the first http request was still transferred to instance one but all following http requests are transferred to instance2
>
> This is consistent behavior
> Questions
> 1. Why were the requests of ongoing session not handed over to second instance?
> 2. After restarting test why was even first request sent to the unhealthy instance ..what is healthcheaker for. (Yes it is enabled with url set to context root of the application)
>
> Any kind of input will be highly appreciated
>
> Appserver version: 8.2 (No I cant upgrade to 9.1)
> [Message sent by forum member 'anzy' (anzy)]
>
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