CODEWITHSUNDEEP
jmeterperformance-testingload-testing
Anandh R
Anandh R

Reputation: 109

I have some basic questions about jmeter anybody can?

  1. What is the use of Synchronizing Timer?
  2. What is the purpose of "Std deviation" in summary report?
  3. What is the difference between running the jmeter script in GUI and Command Prompt?

Upvotes: 1

Views: 69

Answers (2)

TestingWithArif
TestingWithArif

Reputation: 894

JMeter official documentation defines Synchronizing Timer very well.

The purpose of the SyncTimer is to block threads until X number of threads have been blocked, and then they are all released at once. A SyncTimer can thus create large instant loads at various points of the test plan.

So, we can use Synchronizing Timer in order to create required loads. For example if we use 3000 value in Synchronizing Timer then all the requests will keep accumulating for 3 seconds and will be instantly released after 3 seconds, thus creating greater load.

Standard Deviation gives you an idea that how much variation is in results from the average. In general we can say that, a lower Std deviation value means good performance and higher std deviation value points to issues.

JMeter GUI mode is suitable only for creating scripts or debugging them. While performing actual load tests, JMeter should be run from CMD as it is more efficient and consumes less memory as compared to GUI mode. Check this JMeter blog on how to run JMeter from CMD.

Upvotes: 0

Tanveer Shaikh
Tanveer Shaikh

Reputation: 1688

Synchronizing Timer: Consider that you are load-testing. Start 25 threads (with synchronizing timer disabled).

You will note that the start time of first thread will have a difference of about 800ms to 1000ms when compared to the last thread. This ideally is not a good testing condition for loads.

Now consider the same scenario with synchronizing timer enabled. You will notice that the start time of all the threads is absolutely the same. Ideal scenario for load testing.

Std Deviation: Standard deviation quantifies or indicates how much the response time varies around its mean or average. I would suggest not to judge the system performance based on Standard Deviation. In reality this just indicates how much the system is fluctuating. Nevertheless, Deviations should be minimum i.e. less than 5%.

GUI and CMD: Lets just say that on one hand, the GUI makes the program more intuitive; on the other hand, it consumes more resources. JMeter GUI should only be used for test development or debugging. Personally, I do not advise using JMeter in GUI mode if you are initiating an actual load test.

Upvotes: 2

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