Target Throughput behavior of Constant Throughput Timer in JMeter

0
votes

As per the Documentation - "Of course, if the server is not able to handle such a load, the throughput will be lower." How is this behavior handled and throughput calculated?

Suppose I set the target throughput as 1500/min but my system could handle only 1000/min, what kind of feedback behavior is expected by JMeter and how is the total throughput affected?

Will the JMeter still try to achieve 1500/min with higher error rate (for failed requests) or JMeter shoots the throughput to 1500/min but gradually comes back near to 1000/min based on certain factors like error rate? If yes, what are the factors determining this step-down, any insight/reference to understand this step-down behavior?

2
jmeterjmeter-5.0
Got useful related information - stackoverflow.com/questions/62514181/… – Madhuri Jain

2 Answers

1
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Either you do not have enough threads in the test plan to achieve your desired TPS or your application response time is higher.

The total number of requests you will be able to make through JMeter depends on your application response time.

So you will need at least 25 threads to achieve 1500/min if your average response time is 1 second (assuming there is only 1 request).

If throughput isn't increasing even after providing with enough threads but the response time increasing and some of your requests got failed, then this indicates the performance bottleneck!

1
votes

JMeter cannot send requests faster than your application is capable of responding. If your application can only serve 1000 requests per minute - you will have 1000 requests per minute no matter how many threads you have in the Thread Group or how many requests per minute you specify in the Constant Throughput Timer.

Also be aware that:

  1. Constant Throughput Timer can only pause the Threads, it will not do anything if the current amount of threads is not enough to reach/maintain the desired throughput
  2. Constant Throughput Timer is accurate enough on minute level so consider choosing proper ramp-up settings otherwise you can stress your application during first minute of your test