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List:       jmeter-user
Subject:    Re: Caching
From:       Martin Ramshaw <mramshaw () alumni ! concordia ! ca>
Date:       2002-05-16 17:31:35
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>Does JMeter accurately simulate browsers?  Specifically, with regard to
>caching request results.  If I've got 50 requests that run, and they all
>get images,  does it re-get images with each URL, even if they're the
>same?

Well, it depends on the browser (and how that browser is configured).

There are usually browser settings wrt. cache size, and when the page is
actually fetched (once per session, always, etc).

There may also be content cached by an intermediary (a caching proxy,
or something similiar).

In theory, there are meta-tags to override this behaviour. In practice,
they may or may not work.

The only authoritative place to look is your server logs. Assuming they
follow the CLF standard (Apache, for instance), then the critical thing
to look at are the last two fields in the log entries (HTTP response code,
and bytes transferred). If you are not getting the hits you expected, it
may be due to the browser settings. If you are seeing a lot of '304'
response codes, then those files are being served from cache.

I haven't checked into how JMeter itself is coded (perhaps someone
can elaborate on that for us), but I think that what JMeter does will make
a lot more sense if you are aware of the factors listed above.

	Regards


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