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From sebb <seb...@gmail.com>
Subject Re: Strange Behaviour with JavaImpl & Load Balancer
Date Mon, 25 Mar 2013 17:21:35 GMT
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?

>    - 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.

> -
> 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.

>    - 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.

>
>
> 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

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