Load Testing: Concurrent Users verses Simultaneous Users
Posted on Sep, 2012 by Admin
It seems like on every new project, there is a need to educate members of the project team on the difference between concurrent users and simultaneous users as it applies to load testing applications.
Concurrent = users on the system using resources.
Simultaneous = users executing the same code at the exact same time.
Concurrency has various levels. I generally it explain things this way to my clients at the initial project kickoff meeting to make sure everyone agrees with the definitions:
- Application Concurrency – how many vusers are on the system doing something?
- Business Process Concurrency – how many are doing a specific business process right now?
- Transaction concurrency – how many are executing the same code at the exact same time at a given moment?
The relevance of any of these depends on what your testing objective is. Most projects that are trying to create a load test (not a stress test), and will prefer application concurrency.
Do you define concurrency differently? Let me know your thoughts on this by putting a comment in the section below.