Load testing should be done locally or remotely?

Question

I am using a vps for my website so I don't believe I can access it from the local network or something. I am using digitalocean as a vps.

So where should I install tools like ab, siege, jmeter etc. , locally on the vps / on my own computer (client) / on another droplet(vps) in the same region and connect to the web server droplet via private network?

From my understanding if I use those tools on the vps itself, they might use too much of the cpu and ram (same cpu and ram the web server uses) for the test to be correct.

On the other hand testing remotely might end up with bad values because of network bottleneck. Is this the case if I use another vps on the same subnet (digitalocean private network function for example)?

I am lost, both solutions seem wrong so what am I missing?

Answer 1

We get good results using Unix machines from Amazon Webservices as load generator. You get not such a clean result like Dimitri mentioned, when the load generator is located in the same network. But you get a realistic result, like the enduser will get it too. With our scenario we evaluate some key values during execution like CPU, DB connections and amount of changed data sets in db during test. We repeat the test several times because there is always some variance in the result. The loadtest in the same network will deliver more stable results and can be compared to a measurement in a laboratory, but I think it is very good to know how your application behave in reality.

Answer 2

The best option is to install the load generator on another VPS residing in the same subnet as the application under test - this way you will be able to get more "clean" results not impacted by connect times / latency

Having both application under test and the load generator at the same machine is not recommended as load testing tools themselves are very resource intensive and you may run into the situation when both applications are "struggling" for resources hence load generator is not capable of sending requests fast enough and application under test cannot handle requests properly. In general it is recommended to keep an eye on resources consumption by the application under test/load generators in order to ensure that both have enough headroom, you will also be able to correlate increasing number of virtual users with increased resources consumption. You can use an APM tool or alternatively JMeter PerfMon Plugin if you don't have any alternatives in place.

As a fallback you can use your local machine for testing, however make sure that you have enough bandwidth (you can check it using i.e. https://www.speedtest.net/ service) and your ISP is aware of your plans and won't block you for the fraudulent action (as it might be considered a DOS attack)