Unexpected cancel signal and 503 response code - spring-boot

Question

When working on my reactive REST endpoint using Spring Webflux, I realized that, if the returned Publisher does not complete in ~30 seconds, it is being canceled and a response code 503 is returned.
I haven't seen this behaviour documented anywhere.
An example REST controller:
package myapp.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Mono;
import javax.servlet.http.HttpServletRequest;
import java.time.Duration;
#RestController
public class TestAlationIndexingRestController {
#RequestMapping(
value = "/test",
method = RequestMethod.GET
)
public Mono<String> test(HttpServletRequest request) {
return Mono.delay(Duration.ofMinutes(2)).thenReturn("Late");
}
}
Response: 503 with no response content
My question: How can I disable this behaviour, or at least increase the timeout?
Note: I have attempted to use the application property server.connection-timeout: -1 or server.connection-timeout: 15 without success - the request still timed out out after a little over 30 seconds.
I'm using the Spring Boot dependencies (version 2.1.6-RELEASE):
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-reactor-netty</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-json</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
and
<dependency>
<groupId>io.projectreactor</groupId>
<artifactId>reactor-core</artifactId>
<version>3.2.12.RELEASE</version>
</dependency>

Answer 1

i've been stuck on such problem for several days. finally i find out the solution.
first add the async timeout configuration on application.yml
spring:
mvc:
async:
request-timeout: 60s
if the above configuration does not work. then try to add the following configuration in java code
#Configuration
#EnableWebMvc
public class ConfigurerAdapter implements WebMvcConfigurer {
#Override
public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
configurer.setDefaultTimeout(3600000);
}
}
you may also get some clue from here https://docs.spring.io/spring-framework/docs/5.0.2.RELEASE/kdoc-api/spring-framework/org.springframework.web.context.request.async/-timeout-deferred-result-processing-interceptor/index.html