How do I make JMeter create simultaneous HTTP requests for a workflow?

Question

I have a workflow that involves saving some data, and then updating it a few seconds later. I've created a CSV file with parameters like so:

ID,Success
1,true
2,false
3,true
4,false
5,true

And so on and so forth. The first HTTP request is to save a new ID:

POST http://server/save
{ id: 1 }

And the second HTTP request updates the ID with the status:

POST http://server/update/
{ id: 1, success: true }

I've created a JMeter test to benchmark this workflow. I created a Thread Group with the following steps:

1. Do save request
2. Wait a random period between 5 and 30 seconds
3. Do update request

I've set my Thread Group to use 2 threads at once as an initial test. However, I've noticed that what happens is actually this:

Thread 1
----------------------------------------------------
| 1. Do save request                               |
| 2. Wait a random period between 5 and 30 seconds |
| 3. Do an update request                          |
|--------------------------------------------------|

Thread 2
----------------------------------------------------
| 1. Do save request                               |
| 2. Wait a random period between 5 and 30 seconds |
| 3. Do an update request                          |
|--------------------------------------------------|

Problem is, what I'd actually like to do is ensure that there's always 2 simultaneous HTTP requests to the server. In this case, it spawns 2 threads and runs through the ENTIRE workflow as one thread, meaning that I can't guarantee a certain load on the server. What I'd like for it to do instead is this:

Thread 1
-------------------------------------------------------
|                                                     |
|  HTTP request                                       |
|  **********************************************     |
|  * 1. Do save request                         *     |
|  **********************************************     |
|                                                     |
|    2. Wait a random period between 5 and 30 seconds |
|                                                     |
|  HTTP request                                       |
|  **********************************************     |
|  * 3. Do update request                       *     |
|  **********************************************     |
|                                                     |
|-----------------------------------------------------|

Is there a way that I can write my JMeter test such that it will ensure that there are always 2 simultaneous HTTP requests on the server? Also, the update request must happen after the save request, otherwise the ID will not exist.

Here's an image of my JMeter test:

The while controller simply processes every line in the CSV file.

Why do yo want to use one thread sending quiet random requests instead of two threads sending requests in a sequence? — Andrei Botalov
Because I need to simulate a workflow where the user saves some data, confirms it on his page, and then sends the success status. Think shopping cart, for example. User first creates a shopping cart, confirms on his screen that the cart looks correct, and then places the order. — Daniel T.
Any news on that ? Was my answer helpful ? If yes you should accept it, if not you can comment — UBIK LOAD PACK
Hi PMD, I've found another solution using JMeter Plugins, available here: code.google.com/p/jmeter-plugins. It provides a Throughput Shaping Timer which does exactly what I need (limit the number of requests per second to the server). — Daniel T.

UBIK LOAD PACK UBIK LOAD PACK · Accepted Answer · 2012-11-07T07:36:08

I am sorry to say I don't understand you question. What do you want to achieve exactly, particularly in your last workflow description.

Anyway if you notice that you don't have simultaneous requests with 2 threads that can be totally regular as you have high pause time and only 2 threads.

Try with 100 threads you will see you have simultaneous requests.

Some notes about your test plan:

You don't need while controller to iterate over CSV, just set iteration in thread group to infinite
remove View Tree Results and Response Time Graph when you load test

How do I make JMeter create simultaneous HTTP requests for a workflow?

2 Answers