Exception: java.lang.ClassCastException: com.blazemeter.jmeter.threads.DynamicThread cannot be cast to org.apache.jmeter.samplers.SampleResult

Question

I am currently using Blazemeter to run load (performance) tests for a Java application, but I am getting this error. When I run it locally on my machine, this error does not occur.

Under 'scenario definition' my test starts off with a standard jmeter thread group. I did a bit of searching and realised that com.blazemeter.jmeter.threads.DynamicThread comes from the CustomThreadGroups plugin, so I have also uploaded the appropriate jar file plugin jmeter-plugins-casutg-2.9.jar file.

Screenshot of scenario definition

Screenshot of error

Would just like to check if there is some other jar file that I need to upload to solve this error, or if there is another method to solve this issue? Thank you.

Answer 1

Normally you should raise this form of questions to BlazeMeter Support as they should have better understanding of their infrastructure.

With regards to your question itself, most probably you're suffering from a form of a Jar Hell as:

• BlazeMeter uses Taurus under the hood for kicking off JMeter tests which automatically downloads JMeter Plugins so it might be the case your plugins versions clash with the plugins at their end
• You need to remove one of joda-time libraries as you cannot tell for sure which one will be loaded into classpath and in case of API inconsistency you can get unpredictable errors.