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From sebb <>
Subject Re: JMeter Performance evolution : My 2 cents
Date Mon, 28 May 2012 09:35:20 GMT
On 27 May 2012 23:02, Oleg Kalnichevski <> wrote:
> On Sun, 2012-05-27 at 23:08 +0200, Philippe Mouawad wrote:
>> Hello Oleg,milamber,
>> Thanks for your investigations.
>> Oleg, Regarding connectionmanager, do you think it's better to use one
>> connmgr for all vus ?
>> Today we use one per VU but we reuse httpclient instance when downloading
>> embedded résources in parallèl mode.
>> What would be the compromise ?
>> Thanks
>> Regards
>> Philippe
> Hi Philippe
> It really depends on what you define as 'better' and what your
> objectives are. If your goal is to emulate load generated by 20 browser
> instances as realistic as possible you should be using a separate
> connection manager per virtual user. (In this case, though, you should
> be using a pooling connection configured to allow up to 2 simultaneous
> connections to the same host instead of a basic connection manager with
> a single connection).

Why would 2 connections be needed?

> If your goal is to generate as much load as
> possible using 20 virtual users you should be using a pooling connection
> manager configured to allow up to 20 connections to the same host shared
> by all virtual users.

If 2 connections are needed for the first case, wouldn't we need some
spare connections in this case too?

> You should also take into account that Java standard HttpUrlConnection
> is not well suited for the former scenario as it always uses one global
> connection pool for all its instances. This is likely to be the reason
> why the HttpUrlConnection based sampler tends to yield the highest
> request per second in the performance tests.

JMeter has historically tried to ensure each VU behaves completely
I don't think we should change that by default.

However, it might be worth considering optionally using a shared
connection pool.


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