Why is JMeter losing a value?

Question

I am using JMeter to load test a Moodle server. However my Regular Expression Extractor seems to lose the session key value.

Here is the Regular Expression Extractor I am using:

However, after sending roughly 15 HTTP requests, the variable reverts to its empty value. I have tried disabling the last call that successfully uses this variable, and the two following calls. But with no change.

I also tried creating a second instance of this extractor right before this variable goes null, and it still fails to work.

I am new to JMeter, so any additional information I should look up would be greatly appreciated.

Answer 1

JMeter PostProcessors are obeying Scoping Rules, to wit:

1. If you put the Regular Expression Extractor as a child of the Sampler - it will be applied to that sampler only

   • Sampler 1
     • Regular Expression Extractor (applies to Sampler 1 only)
   • Sampler 2

2. If you put the Regular Expression Extractor at the same level as the Samplers - it will be applied to all the samplers.

   • Sampler 1
   • Regular Expression Extractor (applies to Sampler 1 and Sampler 2)
   • Sampler 2