JMeter Properties (Real Time Control)

Change Any JMeter Property in Real Time

You may want to alter the behavior of your test while the test is running. BlazeMeter allows you to remotely change the value of any JMeter property using the "Remote Control" feature.

To use this feature:

  1. Add one or more properties to the JMeter Properties dialog when configuring your test.
  2. Click the Remote Control button at the top of the reporting screen during your test.
  3. Enter new value(s) and click Send to update the property on all engines.

Here is a video showing how to set-up and use this feature. Maximize the video for best viewing.

Another Example: Changing Throughput in Real Time

Suppose you want to determine the capacity of your website in hits/s using JMeter's Constant Throughput Timer and you are not sure about what throughput to test at. 500 hits/s? 1000 hits/s? Using real time test control, you can make an initial guess about what the throughput should be, then update it as you see the results of the test.

To do so, you will create your JMeter test script as normal, but in your throughput field, put ${__P(hits)} . A property of this form signals to JMeter that it can be controlled during the test.

*Please note that is the 'Constant Throughput Timer' the values will be in hits per Minute, while Blazemeter's graphs are per hits per second.

Now, you can upload your script as normal, but before you save your test configuration, go to the Advanced Test Properties section, so that your throughput controller has an initial value.

Okay, once you start your test, and with BlazeMeter's real time reporting, you will find that your servers are doing fine with 500 hits/s. You can go to the live report and reset the property like so.

  • Select 'Remote Control' in the upper right buttons panel.
  • Update the value of the property by entering a 'New Value'.

Helpful Hints

Note that when you are setting a throughput controller, the values are per server. For example, if your throughput controller is set to 250 hits/s, and BlazeMeter allocates your test 5 servers, your server will receive a throughput of 1250 hits/s from BlazeMeter.

The typical use case we envision for this feature is for users who need a load test that follows a step-function like pattern, i.e. "Okay, our servers can handle 1000 hits/s, let's try 1500 hit/s." It may also be used to turn load on-and-off over the duration of the test.

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