Forum Discussion

aduncan's avatar
New Contributor
12 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,


3 Replies

  • MPunsky's avatar
    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!