Sending in consecutive sets of users in jmeter

Question

My question is similar to this one: Trying to simulate users logging in but staying idle

However, there weren't really any suggestions on how to implement on jmeter.

More specifically, this is the scenario I cam trying to replicate:

Let's say xxxx number of users all log in. While those xxxx users are logged in and doing something, a new set of yyyy number of users log in and do something as well. So essentially there are now xxxx + yyyy number of users. Rinse and repeat. I want to try and take down the server.

The Ultimate Thread Group doesn't fit what I need. The reason is because within the hold load time limit, all of the requests inside that thread group will be continuously executed. I don't want that. I just need them to execute each http request once.

Is there a way to do something like this in jmeter? Or would I have to create two separate test plans and run them? Perhaps I can do some kind of loop? While xxxx users are still doing something, send in new yyyy users.

Answer 1

Your I just need them to execute each HTTP request once. stanza conflicts with the scenario described as the thread, representing a virtual user will be shut down when there is nothing more to do and there are no requests/loops defined.

In regards to having separate test plans: there is no need to have different test plans as you can have different thread groups which can run at the same time.

Personally I would go for the following scenario:

• Main Thread Group with as much virtual users as your machine allows and infinite loops

  • HTTP request
    • Constant Throughput Timer with N requests per minute as initial load.

• Another Thread Group

  • Beanshell Sampler to change throughput
    • Constant Timer to sleep for S seconds

The idea is to start with i.e. 20 requests per second and after i.e. 1 minute set the load to be 40 requests per second and so on.

To do so:

• Start JMeter with throughput property defined matching your initial throughput.

  jmeter -Jthroughput=120 ....
  

120 requests per minute will give 20 requests per second throughput

• Enter ${__property(throughput,,)} into "Target Throughput" field of Constant Throughput Timer

__property function will set initial throughput to be 20 requests per second

• Enter 60000 into Thread Delay field of Constant Timer in second Thread Group

• Add the following code to Beanshell Sampler

  int old_throughput = Integer.parseInt(props.get("throughput"));
  int new_throughput = old_throughput * 2;
  props.put("throughput", String.valueOf(new_throughput));    
  

In this scenario each 60 seconds the load will be increased twice.

See How to use BeanShell: JMeter's favorite built-in component guide for more useful examples of extending JMeter tests with scripting and comprehensive information on Beanshell components.