how to find out which function(s) took most time during API invocation?

Question

i am trying to debug why my spring boot application takes around 200-ms to respond to an API, and for subsequent hits of same API it takes around 10-ms. no caching is involved in API. I am using VisualVM and seems there is a CPU spike only for first time and no spike is observed for subsequent hits.

How can i get to know which functions took most time/intensive when i made the first API call.

Update: Why are Spring Rest services slow on the first request?

Answer 1

You can use build profiler in Intellij Idea and check the Flame Graph .

Flame Graph – a convenient way to visually assess the performance of various code paths and their share in overall CPU/memory usage

I'm not going to copy the whole docs, but check the Intellij Idea docs https://www.jetbrains.com/help/idea/read-the-profiling-report.html

Answer 2

what about Glowroot it's a very useful and good Java Agent, that will help you to find your problem