What is the difference between the constant timer and ramp-up seconds in jmeter?
Ramp-Up period is set in thread group. It is used to define the time, which JMeter takes to create total no of threads (users).
For example, this is configuration:
Number of Threads (users): 100
Ramp-up Period (in seconds): 10
Loop Count : No
That means,10 users will be created in each second. So we will have..
10 users after 1st second
20 users after 2nd second
..
..
100 users on 10th second
Normally, the ramp-up period is set as per our load-scenario. If we want to increase load slowly and step by step then we will use higher ramp-up value and vice-versa.
Constant Timer is quite different to Ramp-up period. Constant Timer is used to introduce a fixed delay between consecutive requests. This delay can be implemented at a specific request or for all requests in a controller/thread group etc.
Constant timer is normally used to give delays between requests as in real-time scenarios real-users give delays between doing different actions. So to create real-time scenario we introduce think-time by using constant timers.