concurrency as users per second

[ghost]

Do you think it would be an idea to specify concurrency as users per second as Gatling does?

[mhjort]

I didn't know that Gatling has a such feature. But yeah it should not be that hard to implement. Definitely something to be added to clj-gatling.

So in options you could either use :concurrency or then :requests-per-second

However, I am not sure when I have time to implement this. PRs are always welcome ;)

[holyjak]

I could implement this perhaps. @mhjort could you be so kind and point me where in code to look / start? Thank you!

[viesti]

Just dropping a friendly ping, I'd like this feature too :)

[mhjort]

Thanks for pinging. I had a quick look on this. Noticed it requires some thinking and totally forgot to answer :(

Since this feature was proposed clj-gatling has got quite a lot of other new features. So they should be adapted too. One of those features is :concurrency-distribution. So if new :request-per-second option is used there should be a similar :requests-per-second-distribution option.

The core functionality for running the simulation is in simulation.clj. That is a good place to start. It contains a full test suite in simulation_test.clj.

The way simulation works now is following:

• clj-gatling starts as many go loops as is the required concurrency
• go loop is inside a function called run-scenario-constantly
• In every loop round request is started if concurrency is less than target concurrency

So the way to implement requests per second could be following:

• Start go loops based on what is the maximum requests per second
• Somehow keep track how many requests per second we are running at the moment
• In every loop round start a request if we are running less than targeted requests per second

I have not tested that idea so this probably needs some testing. However, this could be a one way where to start. Are you still interested @jakubholynet ? It would be great if you could work with this.

[viesti]

There's also this nice little library for throttling: https://github.com/brunoV/throttler. Might not be of direct use but the token bucket idea for rate limiting could be useful.

[holyjak]

Thank you! I run out of time but perhaps somebody else will take the ball :-) If not, then I will the next time I have an opportunity.