A Thread Group defines a pool of users that will execute a particular test case against your server. In the Thread Group GUI, you can control the number of users simulated (number of threads), the ramp up time (how long it takes to start all the threads), the number of times to perform the test, and optionally, a start and stop time for the test.
- Thread group elements are the beginning points of any test plan.
- All controllers and samplers must be under a thread group.
- Other elements, e.g. Listeners, may be placed directly under the test plan, in which case they will apply to all the thread groups.
- It controls the number of threads JMeter will use to execute your test.