Subscription is not reliably created when using native images

[klopfdreh]

Expected Behavior

The subscription is created and everthing is working like expected all the time.

Actual Behavior

Sometimes a subscription is not created and the related code just runs in a timeout - I just thought this is a problem of the specific implementation of Prometheus RSocket Proxy, but the more I digg into it the more I think this is an issue that the reactor-tcp-epoll pool of the subscription is not created reliably within native images created with graalvm - for more information see: micrometer-metrics/prometheus-rsocket-proxy#94

Steps to Reproduce

I created a setup to create native images and to test it against a local running Prometheus RSocket Proxy: https://github.com/klopfdreh/prometheus-rsocket-native-test - but sadly I was not able to reproduce it without K8 setup.

1. Create a Deployment with a prometheus rsocket proxy server
2. Create a service which delegates tcp port 7001 to the pods created with the deployment
3. Run a native Spring Boot application with prometheus rsocket proxy client which connects to the prometheus rsocket proxy server via the service

Possible Solution

N/A

Your Environment

• reactor-core 3.7.3
• GraalVM: bellsoft-liberica-vm-openjdk23+38-24.1.0+1-linux-amd64.tar.gz
• Prometheus RSocket Proxy 2.0.0-RC1
• Netty 4.1.118.Final
• Spring Boot 3.4.3

[klopfdreh]

When I set spring.threads.virtual.enabled=true and use Java 21 instead of Java 17 to compile the code the issue seems to be gone.