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aduncan's avatar
aduncan
New Contributor
11 years ago

[LoadUIWeb] Why does a continuous load test make the same request at slightly different times?


I have a load test with 200 virtual users. The load is continuous. All other settings are set to default. Once the test completes, I verify the Messages panel and sort it by Request #. Each Request # (1-62) displays 200 users (1-200).

Looking at the Time column, almost all users logged Request #1 at the same time 15:07:18.

However, users 128, 129, 130 logged Request #1 at 15:07:19.

Users 194, 195 logged Request #1 at 15:07:21.



If I specify a continuous load, why do 195 users make Request#1 at the same time and the remaining 5 users make the same request a few seconds later? 

Using a smaller set of virtual users, let's say 20, I do not see the discrepancy, everybody makes the same request at the same time.





Thanks for your help,

Antje  


3 Replies

  • MPunsky's avatar
    MPunsky
    SmartBear Alumni (Retired)
    Hello Antje,



    This is due to the number of VU's.   Even though all virtual users were set to start at the exact same time, a few vu's started slightly later due to your machine's processing overhead.   In any test with more than a very few Virtual users, it is recommended to use a load profile that staggers the start time so as to not create artificial bottlenecks.



    In addition to selecting continuous load, also select "stepwise" under load profile, and start the vu's 1 or two seconds apart.



    Hope this helps!