What is load testing?
Load testing is describes how your application behaves for a given load at peak hours as well as how much time it will take to provide response for a particular request to verify your application speed,performance of the application.Load testing can be done with JMeter(Learn JMeter) or any other open source tool but in open source tool you can't run with more VUsers to check behavior of your applications.
Calculate Vusers for load testing
You can calculate number of vusers required for load testing with a basic formula as below
No of Vusers = TPS * (Response Time + Think Time)
TPS – Transactions per Second
Now here you can't simply provide 50,70,100,250,500 etc VUsers to test load on your applications,above requirements are given by the clients in below formats,then you have to calculate based on client requirements.
Business NFR:
Business NFR contains business requirements about application under test,in order to verify application performance with load testing.
Details:
Details will contain test scenarios.
Example : Verify Bank account details.
Business Rules:
Business rules contains actual results as per 3 months old data or 6 months old data with the help of analytic,Business Remarks gives below details about application(AUT).
Number of Transactions per Seconds : 600
Average Response Time : 3 sec
Think Time : 3 sec
So now it is easy to calculate number of virtual users required for a test scenario as below
Number of Virtual Users = 200*(2+1)
Number Of Virtual Users = 200*3
Number of Virtual Users = 600
So required virtual users for your test scenario is 600 VUsers for peak loads,some time users will vary may be less or more but in peak time users will increase suppose example as Festival time most of the companies running promotions on their applications to attract new users at that time number of users automatically increase,this is called peak load time.