How to generate random number using beanshell post processor in JMeter

Question

I am trying to generate a random number using beanshell post processor but I am continuously getting an error

 "ERROR o.a.j.u.BeanShellInterpreter: Error invoking bsh method: eval   In file: inline evaluation of: `` try {....."

I am fetching the total count of matching records through Regular Expression extractor and passing the variable to the Post processor but it's not working.

Please see the screenshot.

Answer 1

1. Don't inline functions and/or variables in form of ${CountID} into Beanshell scripts as they may resolve into something which will cause compilation error or other form of unexpected behaviour. Replace this line:

   int count = ${__Random(1,counter,)};
   

   with this one

   int count = ThreadLocalRandom.current().nextInt(1, counter);
   

2. log.info(count); line won't work as you cannot print an integer to jmeter.log file, you need to cast it to String first so change this line to

   log.info(String.valueOf(count));
   

3. Consider using JSR223 Elements and Groovy language instead of Beanshell as Beanshell interpreter has worse performance than Groovy engine.

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If your target is to get a random match you can do it without any scripting using only JMeter Functions like:

${__V(countID_${__Random(1,${countID_matchNr},)})}

See Here’s What to Do to Combine Multiple JMeter Variables guide for more details.