CODEWITHSUNDEEP
node.jsapijmeterload-testing
Luca01
Luca01

Reputation: 43

Why does the response time curve of NodeJS API become sinus like under load?

I am currently performing an API Load Test on my NodeJS API using JMeter and am completely new to the field. The API is deployed on an IBM Virtual Server with 4 vCPUs and 8GB of RAM. One of my load tests includes stress testing the API in a 2500 thread (users) configuration with a ramp-up period of 2700ms (45 min) on infinite loop. The goal is not to reach 2500 threads but rather to see at what point my API would throw its first error. I am only testing one endpoint on my API, which performs a bubble sort to simulate a CPU intensive task. Using Matplotlib I plotted the results of the experiment. I plotted the response time in ms over the active threads. enter image description here

I am unsure why the response time curve becomes sinus like once crossing roughly 1100 Threads. I expected the response time curve keep rising in the same manner it does in the beginning (0 - 1100 threads). Is there an explanation for the sinus like behaviour of the curve towards the end?

Thank you!

Graph:

Red - Errors

Blue - Response time

Upvotes: 1

Views: 181

Answers (1)

Dmitri T
Dmitri T

Reputation: 168082

There could be 2 possible reasons for this:

  1. Your application cannot handle such a big load and performs frequent garbage collection in order to free up resources or tasks are queuing up as application cannot process them as they come. You can try using i.e. JMeter PerfMon Plugin to ensure that the system under test doesn't lack CPU or RAM
  2. JMeter by default comes up with relatively low JVM Heap size and a very little GC tuning (like it's described in Concurrent, High Throughput Performance Testing with JMeter article where the guy has very similar symptoms) so it might be the case JMeter cannot send requests fast enough, make sure to follow JMeter Best Practices and consider going for distributed testing if needed.

Upvotes: 1

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