Waiting for a page change in JMeter

(This article is part of the JMeter Series)

While testing a Rails application there was a situation where a background worker (DJB or background task) would get an order to execute and eventually the completed order would appear on a page.

Thus we needed to wait for the page to be updated and continue the test after.

User Defined Variables

I’m predefining used variables here - see “We set up our variables” in the Extracting text from a page and using it somewhere else in JMeter article for an exaplanation why.

User Variable Screenshot

Clear Loop Variable

This step is not strictly necessary in our example here, however if you want to reuse this sequence of steps more than one time - that is call it from different places, then you need to clear the loop variable first.

Reset Variables Screenshot

Debug

Since creating these steps was not easy, I’ve put a debug statement in so that I see, when JMeter calls into these steps and to see how the variables are set.

Debug Screenshot

The While Controler

Here we really start the loop.

While Loop Screenshot

I’m not sure whether if would be better to use BeanShell commands here instead - using JavaScript to test the loop condition works in any case…

Getting the page

We get the page we want to check.

Get Page Screenshot

Extract the data we want to check from the page and assign it to our loop variable

Get Page Screenshot

Make sure our request is not being cached

It’s better - as far as we can - to be sure we force the web application to recreate the page we’re waiting for to change. I’m not sure I’ve done it right here, however it works:

Don't cache Screenshot

Wait a bit before re-looping

We wait two seconds here before retrying.

Sleep Screenshot

You can download this JMeter test from here

Tomáš Pospíšek, 4.1.2011