A thread group is basically a combination of different test plan elements. It is the root of a test plan and it controls the basic central parameters.
In order to create a test plan you may have to create at first a thread group and configure its number of threads, the ramp-up period, the loop counts and the behavior in case or error:
- Number of threads: The number of threads that are going to be used to execute the test plan, very important to configure load and stress tests.
- Ramp-up period: Time that JMeter will need to start all threads.
- Loop count: Number of iterations, that is the amount of times that the test is going to be executed.
- Error behavior: What to do in case of error: Stop current thread, stop the whole test, continue…
A Thread Group has also the start and end time configuration options. By clicking the checkbox “Scheduler” a new section with the schedule parameters will appear and you can configure the start and end time of your test.
Once this is configured you can start adding other test plan elements to your Thread group like samplers, listener and timers. We are going to explain all these in the next chapters.