Unique Ids in each Gatling request

Question

  def getrandomNo(): String = {
    return ((rnd.nextDouble() * (1000000.0)).toLong).toString
  }

scenario("scn getart).during(test_duration minutes) {
    exec(actionBuilder = http("req getart")
    .post(apiurl)
    .header("txn-id", getrandomNo()+"_getart")
    .body(apibody)
}

In the above code sample trying to generate unique txn-id for each request. However, observed that it is reusing the same number causing duplicates. Also I tried using the following to generate based on current time still it is causing duplicate when more than 1 requests are fired within 1second.

def getTxnId(): String = {
    "PerfTest_" + System.currentTimeMillis().toString+ getrandomNo()
  }

Any alternate solutions to generate unique ids for each requests irrespective of concurrency?

Thanks in advance.

Answer 1

This doesn't work because your getrandomNo is only called once when building the Simulation. If you don't want to pass a value, but some piece of code you want to get executed on each execution, you have to pass a function:

.header("txn-id", session => getrandomNo()+"_getart")