HOAB

Problem :

I have two thread groups that must be synchronized. I want to use

java.util.concurrent.CountDownLatch

to achieve this.

I read (here, or here) how to synchronize JMeter thread groups (you have to use properties and not variables). Properties can be access in :

• bsh sampler : bsh.shared.<property name>
• jsr223 sample : props.put(<property name>)
• the org/apache/jmeter/util/JMeterUtils.class is the source of these properties.

I add to my test plan an initial element in bsh, jsr223 to create the latch. But when I get the latch in the thread groups, I always had different instance of my shared latch.

Solution :

Easy when we know.

I made the mistake to add the piece of code in a Pre-Processor

• Test Plan
  • PreProcessor BSH : init latch
  • Thread Group 1
    • Sampler BSH : wait for latch
  • Thread Group 2
    • Sampler BSH : count down latch

In this case, the PreProcessor is run before each thread initialization. I run X times the preprocess sample.

Correct test plan :

• Test Plan
  • Set up Thread Group
    • Sampler BSH : init latch
  • Thread Group 1
    • Sampler BSH : wait for latch
  • Thread Group 2
    • Sampler BSH : count down latch

The setup Thread Group is run before the others thread groups (these ones are parallel until you say not to do)