Parallel Processing of Requests in Jmeter

Question

By default JMeter sends all the requests sequentially. Is there any methodology to send the requests concurrently at the same time for a single user i.e. something similar to web_concurrent_start () and web_concurrent_end () functionality in Load Runner. Any thoughts / ideas in this regard?

Answer 1

JMeter's equivalent of the web_concurrent_start () would be Synchronizing Timer, however depending on what you're trying to achieve you may need to use a different approach.

1. For simulating browser's behaviour with regards to images, scripts and styles it would be using "Retrieve All Embedded Resources" and "Parallel downloads" in the HTTP Request sampler "Advanced" tab

   

   2. For simulating AJAX requests you may need to do some scripting using JSR223 Test Elements and classes from i.e. java.util.concurrent namespace as JMeter Thread Groups are not designed to kick off more threads than defined.

Answer 2

If your requirement is simulating browser behaviour of sending requests concurrently to load images, .css and .js files, You should have a look at the following answer:

Does a Jmeter thread really approximate a user?

You can send multiple requests in parallel by only specifying the parent URL (let's say stackoverflow.com) and enable the checkbox "Retrieve All Embedded Resources" to send requests in parallel and define concurrent pool size to specify the number of parallel requests to be sent (usually 6).

Note: JMeter parses the HTML response and triggers the requests for the resources specified in HTML response. In JMeter 3.0, it can parses .css files also, but can't parse .js files (a limitation). so, you have to take care of those requests manually (by adding HTTP samplers for those requests)

Answer 3

It sounds like you need a custom sampler to fire asynchronous requests. I added some info here regarding one I am using:

Performance Testing of AJAX calls via JMeter