Performance test - approach

Question

I have User Registration, Flight Search, Book Tickets modules in my application. I have created my JMeter test & I have different thread groups for each module in my test. I verified & it works well.

• Thread Group 1: XX number of users - access the site - click on regression , enter the details & register. (bold -> loop- happening again and again)
• Thread Group 2: XX number of users - access the site - login, - search for flights - (bold -> loop - happening again and again)
• Thread Group 3: XX number of users - access the site - login, book ticket - (bold -> loop - happening again and again)

Issue:

My manager says we need to run all modules (all thread groups) together with appropriate users as that is how It is going to be in Production. Even though i can run them all together, - in case of issues - i would not know which feature of the application caused the issue.

My aim is to run each module separately & find its performance. I think that doing the module wise would be the correct approach to get the response time, resource utilization etc.

Clarify:

• I do not have much experience in performance testing. What is the correct approach / How do you do your test for your application?
• If i have to find server's optimal load (at which it performs better) - what should my approach be?

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Intentionally tagging loadrunner as this question is not specific to JMeter & it is generic.

Answer 1

If your goal is to represent human behavior to assess the risk of deployment then testing each business process atomically will not accomplish your goal.

You appear to be engaging in a process that is more appropriately termed performance unit testing. This is very common with developers (as differentiated from performance testers) who seek to qualify the performance of an individual business process across some number of users. These are also typically classified with non-normal think times (often eliminated altogether), small data sets, smaller than useful test environments and extremely short test durations, such as 5-15 minutes.

Answer 2

You can mark this business scenario as transactions it means the HTTP requests for each module will be grouped for ex- Login requests in one group or transaction , Search flight as one group or transaction and similarly for Book tickets etc. By following this you will be testing it in a integrated manner and it would be a production like scenario too. After your run due to grouping you can easily find out which group of request taking more time either search, book tickets etc... In this way you will get the accurate performance statistics and you will achieve the production like scenario too

Answer 3

The approach really depends on what your goal for the testing exercise is. If you're looking to optimize or profile a particular module, it makes sense to test it in isolation.

However, if you're trying to check if your server scales, or if you have enough capacity, you should test all your modules at once, at or above your expected load levels.

A counter example to your isolated approach:

Say you have to modules A and B. They are both CPU intensive and take up 80% CPU when you run them. You first tested A, it used 80% CPU, you had 20% to spare and it performed fine. Now you test B alone, same result.

Now you go to production and users try to use both A and B modules, both are trying to use 80% CPU and suddenly you don't have sufficient CPU and your performance suffers.

Answer 4

I know this is kind of late but still.

I do not have much experience in performance testing. What is the correct approach / How do you do your test for your application?

As James mentioned, the approach to conducting a performance test in a normal scenario would be to run all the critical business flows at the same time and not in an isolated fashion.

In order to identify issues, we would group the requests under transactions and name the business flows appropriately. This will help in identifying which requests have failed and which feature/portion of the application is at fault.

Running them individually will not provide you more insights simply because, a load testing tool will only be able to confirm the presence of a bottleneck but not the root cause irrespective of the number of business flows involved.

If i have to find server's optimal load (at which it performs better) - what should my approach be?

In order to identify the optimal load for the server, it is mandatory to run all the scripts together as the end users are going to access the application (all critical scenarios) concurrently and not in a modularized manner.