JMeter - User defined counter not incrementing for a Loop

问题

I am quite new to JMeter and I was trying to increment a counter variable pre-defined in User Defined Variables using a Loop Controller and a JSR223 PostProcessor and it seems not working well. I looked at various examples on JMeter loop and counter examples to work this out but the config element Counter was also not incrementing with the loop. Could anybody please let me know what I am doing wrong?

This is the user defined variable counter:

This is how I do loop:

And this is how I am trying to increment the counter using post processor and the log displays that the counter is not incrementing for each loop. I want to get the counter upto 5:

[EDIT] I guess I wasn't clear on why I used ${counter} to test out. I was trying to evaluate the counter variable within another variable as '${__V(transaction_${counter})}' because this needs to be appended to a text file. For example, if transaction_3 has a value "110001", if I do '${__V(transaction_'+vars.get('counter')+')}' to append, the text stored shows "transaction_3" and if I do '${__V(transaction_${counter})}' then I get the correct value "110001" stored in the text file while in next iteration the counter does not increment. Is there a possible way to solve this problem?

This is how I was using the variable within variable and it shows that the values are not changing because the counter is not changing.

And this image is how I am trying to do with vars.get() and it shows that it is just putting the variable name instead of evaluating the value of each item.

回答1:

According to JSR223 Sampler documentation:

JMeter processes function and variable references before passing the script field to the interpreter, so the references will only be resolved once. Variable and function references in script files will be passed verbatim to the interpreter, which is likely to cause a syntax error. In order to use runtime variables, please use the appropriate props methods, e.g.

props.get("START.HMS");
props.put("PROP1","1234");

So amend the last line of your script to look like:

log.info(vars.get('counter'))

Demo:

Also be aware that it's much easier to use:

1. Counter test element or __counter() function, check out How to Use a Counter in a JMeter Test article for more details
2. Loop Controller exposes ${__jm__Loop Controller__idx} JMeter Variable which holds current iteration number

来源：https://stackoverflow.com/questions/53403122/jmeter-user-defined-counter-not-incrementing-for-a-loop