visualVM CPU usage of Unsafe.unpark

[yahyashqair]

Hi guys,
I am debugging a system was built on top of akka 2.6.. and the system has mainly two dispatchers
1- default dispatcher.
2- JDBC dispatcher that uses blocking API. (50 Threads pool size)
and the cpu has two cores.

As you can see in the image unpark method takes too much time in the CPU! why? and how can i fix it.

[laglangyue]

Unpark and park methods occupy too much CPU, indicating that your thread context switches too frequently.

[laglangyue]

Interesting! As a Engineer，I just support some ideas. Maybe you can try java21 Virtual Thread with pekko.

[He-Pin]

I'm not sure your case, but at $work, I'm using Source.queue which introduces a nonblocking queue for task sharing.

[yahyashqair]

@laglangyue I will give it a try in the future.
@He-Pin
If i understand you correctly. Here I am not talking about submitting tasks using ask or tell pattern.
assume we have two dispatcher(executor services).
and we have this kind of logic
Future { // some logic Future {callDB} (dbExecutor) // some logic }(futureExecutor)
Here I am submitting a task to dbExecutor and it will be using some kind of locking which will call unpark and park.
So what can i do here to prevent this kind of blocking. and as I understand you. If i use "tell or ask" pattern, It will not do parking?

[yahyashqair]

After using Async-profiler. I saw that the unpark method doesn't use CPU. Most probably it is an issue with VisualVM.