Forum Discussion

Steve1's avatar
Steve1
New Contributor
11 years ago

Fixed Rate Generator Varying Requests

Hello all,

I have the fixed rate generator component connected to to the SOAPUI Runner.. I set the Fixed Rate Generator to 4 requests per second and when looking at the statistics tab I will see a fixed rate of 4 requests per seconds for a few seconds then I will see the requests start to vary from 2 requests per second generated to 6 requests per second generated. It usually averages out to 4 but it will never remain a constant 4 requests per second.. Why is this?


My best guess is that LoadUI is waiting for a response to come back before sending another request. So if the server is overloaded and takes longer to respond then it will make up for the missed time by having more requests sent which will average out to 4 per second. Can anyone confirm or offer an explanation?

1 Reply

  • OstbergM's avatar
    OstbergM
    Icon for Staff rankStaff
    11 years ago
    You are wrong in the fact that LoadUI does not wait for a request to return before sending a new one, at least not when you are using the Fixed Rate component (Fixed Load is another story).

    The fixed rate sends out X number of requests each second, no matter if the server can handle it or not.
    This makes it real obvious to see what happens when the server can't handle more requests.

    The statistics count responses that arrived during the latest second and the latest second only.
    This means that some requests leak into the next second because they may take an arbitrary amount of time to return.

    Internally this is because the timer that sends requests from a generator (G-timer) and the timer that displays data (D-timer) are not the same, but are started at roughly the same time. This means that if G-timer triggers requests just before D-timer starts collecting data then some requests may return before the D-timer collects them, thereby ending up in the previous data-point.

    These variances in the number of requests sent/received should be taken with a grain of salt and are mostly only visible on very tiny loads.

    I hope that explains your pondering somewhat.

    Best,
    Osten