arrivalCount is not working as expected

hi@all,

i’m using the arrivalCount to simulate a fixed amount of users in a defined duration, like the documentation says (https://www.artillery.io/docs/guides/guides/test-script-reference#fixed-number-of-arrivals-per-second)

The load test i want to simulate requires the usage of arrivalCount, because arrivalRate creates at least one user per second.

For exmaple this should generate 10 users over 5 minutes:

  phases:
    - name: '10 user in 5 minutes (1 user every 30 seconds)'
      duration: 300
      arrivalCount: 10

But at the end, only three users were created:

vusers.created_by_name.S5: .................................. 1
vusers.created.total: ....................................... 3
vusers.completed: ........................................... 3
vusers.created_by_name.S6: .................................. 2

Another thing i recognized is the slow start when using arrivalCount. It needs up to two minutes before the first request is sent.

This leads to the questions:

• Do i expect the wrong behaviour?
• Can this depend on the scenarios i implemented?
• Is there something wrong in my implementations?
• Could this just be a bug in artillery?

[hassy]

The results of the second run you posted look OK.

There’s no output between (1) and (2) because Artillery didn’t generate any VUs in that time period. As soon as one VU was created (some time between 06:27:40 and 06:27:50) and some metrics were generated, we got a report.

The VU is reported as failed because there was a 503 code returned for a request, i.e. it did not complete its scenario successfully.

Hope that makes sense!

[hassy]

hi @BernhardMaier 👋 thank you for a very detailed bug report (I would love it if every bug report we get for Artillery was that detailed!)

I’m going to reopen the issue as it does look like there’s an issue in the first report you shared - we’d expect vusers.created.total to equal 10.