How to find out what loads the processor?

Question

Java

Good afternoon.

On the server, the application (SpringBoot) starts eating one core at 100% days after 5 work.
We know which piece of code, but we can’t understand why - it doesn’t do anything there + there’s a lot of code there, it’s not clear from the logs.

Can I somehow track what exactly the processor is eating?

There is nothing like that in the tests, but we can’t give such a load - the main purpose of the service there is accessing a third-party API that takes money for each request, and their sandbox has small limits....

Answer 1

Try to hook through JMX. Or try profile.
Try using strace or lsof to peek.
Get a dump of a hanging thread - Thread.currentThread().getStackTrace() (just substitute your hanging thread). In general, you can take all the threads and get stack traces from all of them!

Answer 2

It is necessary to remove the profile with Flight Recorder and analyze the state of the streams. I'm betting on thread pool starvation or livelock.