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From Philippe Mouawad <philippe.moua...@gmail.com>
Subject Re: Strange Behaviour with JavaImpl & Load Balancer
Date Mon, 25 Mar 2013 17:31:49 GMT
Hello,
Thanks sebb, see my notes below.

On Mon, Mar 25, 2013 at 6:21 PM, sebb <sebbaz@gmail.com> wrote:

> On 25 March 2013 14:17, Philippe Mouawad <philippe.mouawad@gmail.com>
> wrote:
> > Hello,
> > I noticed a strange behaviour when Load Testing an application recently.
> >
> > There was a Load Balancer in the middle:
> >
> >    - Using Java Implementation I had around 8% of error
>
> What kinds of error?
>
> Session is lost, so it means load balancer redirects to other Apache
ignoring Session Stickiness.

> >    - Using HC3 or HC4 Implementations it was 0%
> >
> >
> > I am sure it comes from Load Balancing as if it pointed on only one
> Apache
> > then there was no issue.
>
> Note that the Java implementation may reuse connections between threads.
> That's one reason JMeter started using HC3 and HC4.
>
> > Now playing around with some Java System properties, I discovered that
> > setting  *-Dhttp.keepAlive=false* fixed the error issue:
>
> That suggests it might be the connection reuse.
>
Agree

>
> > -
> >
> http://docs.oracle.com/javase/6/docs/technotes/guides/net/http-keepalive.html
> >
> > Another way to fix this was to  uncheck KeepAlive checkbox in samplers.
>
> Likewise, that should stop cross-thread connection sharing, as it will
> stop any sharing.
>
> >
> > Now my question is:
> >
> >    - Is this regular ? It seems strange to me that HC31 and HC4 impl do
> not
> >    have this behaviour
> >    - If yes, we should absolutely document this behaviour no ?
>
> I think it is; but it could perhaps be made more obvious.
>
Where is it ? Didn't see any mention of -Dhttp.keepAlive in docs

>
> >    - Could it be a JDK 7 bug ?java version "1.7.0_13"
>
> No, it's by design.
>
> In theory the connnection sharing should be OK (otherwise I assume
> Java would not do it), but maybe there is a subtle bug in the
> application that relies on independent connections.
>
> I think it is something like this or a Load Balancer issue.
But as it is not easy to simulate using Browser, it is hard to prove.

> >
> >
> > Note that tested application was not perfect as it had many Content
> > Encoding behaviour and other non fully standard issues.
> >
> > Thanks for you notes.
> > Regards
> > Philippe
>



-- 
Cordialement.
Philippe Mouawad.

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