Spring Socket leak when using Webclient

Spring Boot Version: 2.3.1, when 2.3.0 has no problem When using a sample Webclient to retrive a remote restful API, this happens.

The test code:

@RestController
@Slf4j
public class WebClientController {

    @Autowired
    private WebClient.Builder webClientBuilder;

    @PostMapping(value = "/wb")
    public Mono<String> wbTest(@PathVariable(required = false) String action) {
        return webClientBuilder.build().get().uri("http://remoteIP:remotePort/privaters/jwks/pub")
                .retrieve()
                .bodyToMono(String.class);
    }

}

After a few requsts, using lsof -p XXX to check, then shows scokets leaked!

java    10823 ircp   32u     sock                0,7       0t0 154700740 protocol: TCP
java    10823 ircp   33u     sock                0,7       0t0 154701211 protocol: TCP
java    10823 ircp   34u     sock                0,7       0t0 154700776 protocol: TCP
java    10823 ircp   35u     sock                0,7       0t0 154700777 protocol: TCP
java    10823 ircp   36u     sock                0,7       0t0 154700778 protocol: TCP
java    10823 ircp   37u     sock                0,7       0t0 154701301 protocol: TCP
java    10823 ircp   38u     sock                0,7       0t0 154701304 protocol: TCP
java    10823 ircp   39u     sock                0,7       0t0 154701307 protocol: TCP
java    10823 ircp   40u     sock                0,7       0t0 154701837 protocol: TCP

Comment From: bclozel

I think this is a duplicate of spring-projects/spring-boot#22091 and spring-projects/spring-boot#21923 This was an issue in Reactor Netty. You can work around this problem by upgrading to Reactor Dysprosium-SR9 (or wait for spring-projects/spring-boot#21938 if you're using Spring Boot).

Thanks for your report!

Comment From: fanticat

@bclozel Thanks for your feedback，I have degrade the Spring Boot to V2.3.0 as temporary solution.