What is the ramp-up period in jmeter?

Question

I ran a test plan with 5 users for a total of 20 seconds and what I am not able to understand is what ramp-up period is in actual. Does it means that each user will get 4 seconds or 20 seconds will be used in total for 5 users?

If case 1 is true(4 second for each user) then the first thread should be completed in 4 seconds but it took 6 seconds to complete it and still the result is passed and next user gets executed? This gets much confusing. I need to clear my doubt as I am not able to find any answers from all the inputs that are available here

Answer 1

As per JMeter Thread Group Documentation:

Ramp-up Period

How long JMeter should take to get all the threads started. If there are 10 threads and a ramp-up time of 100 seconds, then each thread will begin 10 seconds after the previous thread started, for a total time of 100 seconds to get the test fully up to speed.

You have 5 users

• if you set ramp-up period to 0 - all 5 users will start at once
• if you set ramp-up period to 5 - JMeter will start with 1 user and will add an extra 1 user each second
• if you set ramp-up period to 10 - JMeter will start with 1 user and will add an extra 1 user each 2 seconds
• etc.

Once user is started it starts executing Samplers upside down (or according to Logic Controllers) when there are no more samplers to execute or loops to iterate - the thread is being shut down.

Check out JMeter Ramp-Up - The Ultimate Guide article for more information on configuring users arrival rate.

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You might also be interested in Ultimate Thread Group which makes workload definition easier, moreover you will have a chart representing anticipated load. You can install Ultimate Thread Group using JMeter Plugins Manager

Answer 2

If you want threads not to effect test expected time then use instead Thread group's Loop Count as the number of repeatitions you need.

If you want/must use threads calculate ramp period time as

  (test expected time + 1 second) * number of threads