Performance discussion about default openfeign client

[raizoor]

Resume
Discussion about default client performance of spring-cloud-openfeign

Versions
Java 17
Springboot 2.7.18
spring-cloud-dependencies 2021.0.8

Scenario

During a performance tests in a microservice that contain a 3 feign clients, it was possible to saw a high GC usage (i.e. high cpu utilization as well) in two methods, as we can see at profiler image bellow

We have a high tps scenario here - 110tps. The situation was absolutely unstable and we has too much resources to handle with that.

After studying the issue I decided to use lib {io.github.openfeign:feign-httpclient:11.8} and do a new evaluation. To my surprise, we had a significant improvement in resource usage, as feign started using other classes and no longer generated as many objects, as shown bellow

So, my question: Is this the expected behavior of the default implementation or is there something I did incorrectly, because we've a big difference here.

Code

I don't have a high customization clients, only a custom decoder and base64 auth, as bellow

@FeignClient(value = "...", url = "...",
        configuration = ClientConfig.class)
public interface .. {

    @PostMapping("..")
    SpecificObject post(
            @RequestHeader("..") Boolean ..,
            @RequestBody SpecificObject ..
    );
}

[velo]

@raizoor are you willing to run flame charts on your project? That would help identify the issue

[raizoor]

@velo I've some detailed information about cpu / memory local profiler (visualVM) that I can share too. If I can help with other actions, please let me know.

[velo]

A flame chart would show where the problem is.

[raizoor]

[velo]

Bit tough to read this, specially in 2 separated images....
https://github.com/aragozin/jvm-tools/

Can you generate the SVG and send it to me?

java -jar sjk.jar stcap --pid $PID --timeout 1M --output /tmp/stcap.out 
java -jar sjk.jar  flame --file /tmp/stcap.out --output /tmp/flame.html

You probably want to email me https://github.com/OpenFeign/feign/blob/master/pom.xml#L145

[raizoor]

@velo Flame are in your email.