JMeter Concurrent Users Count

Question

I have a web application which is working in production and there are 2000+ users of my application. Now I have to perform performance testing on the system so is there any idea how many concurrent users will be sending requests at a single time? It is presumed that not all the 2000+ users hit the server at the same time.

I am going to use JMeter for load testing of my system so how many concurrent users should I assume must be hitting the server at the same time?

Is there any practice being followed in the world or it varies application-to-application?

Answer 1

when you are setting up a load test you are setting three parameters for threads: Number of users (threads), ramp up period, loop count.

Number of threads is the total number of users you will have when tests is running. You can have multiple runs by setting loop count for your test, but number of threads would never be bigger than the value you have set.

Ramp up period is how long it can take for all threads to be created in seconds. If you set it to for example 10 seconds, it will take this time for all threads to be created in your test run.

Loop count only affects how many times the test will be repeated.

So if you have 100 threads, 0 seconds ramp up period and loop count set to 1, then all 100 threads will be created right away, in your case all 2000.

I would sugest trying out different combinations to see how your web application is handling the load. You will then see and undersand better how JMeter is creating and executing the threads.

I would start with 100 threads, 10 seconds ramp up, 1 loop, and then slowly increase number of threads, decrease ramp up period, and increase number of loops.