How do timeouts work in Hystrix with Observables?

Question

I'm working on a Hystrix-enabled Spring Boot-app using Reactive Observables and trying to figure out how timeouts works. I assumed that if a timeout happened during execution, Hystrix would immediately return a response (fallback or exception). Now this seems not to be the case given my code below. Instead the call to myService.getString() blocks for 5 secs. When it finally returns, the throwable lambda is executed.

Are my assumptions incorrect or is something else wrong below?

@SpringBootApplication
@EnableCircuitBreaker
public class App {
  public static void main(String[] args) {
    ApplicationContext ctx = SpringApplication.run(App.class, args);
  }
}

@RestController
public class MyController {

  @Autowired
  private MyService myService;

  @RequestMapping("/")
  public DeferredResult index() {

    DeferredResult<String> result = new DeferredResult<>();
    Observable<String> res = myService.getString();

    res.subscribe(s -> {
                result.setResult("Got a " + s);
            },
            throwable -> {
                result.setErrorResult("Got a " + throwable.getMessage());
            });

    return result;
  }
}


@Service
public class MyService {

  @HystrixCommand() // Default timeout is 1 sec
  public Observable<String> getString() {
    return Observable.create(subscriber -> {
        if (!subscriber.isUnsubscribed()) {

            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            subscriber.onNext("regular response");
            subscriber.onCompleted();
        }
    });
  }
}

pom.xml: http://maven.apache.org/xsd/maven-4.0.0.xsd"> 4.0.0

    <groupId>dag</groupId>
    <artifactId>dag</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.1.RELEASE</version>
    </parent>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.netflix.hystrix</groupId>
            <artifactId>hystrix-javanica</artifactId>
            <version>1.5.5</version>
        </dependency>
    </dependencies>

    <properties>
        <java.version>1.8</java.version>
    </properties>


    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Thanks for any help!

Answer 1

Please clarify what's the isolation of your hystrix command and what hystrix version did you use?

"Timeouts now apply to semaphore-isolated commands as well as thread-isolated commands. Before 1.4.x, semaphore-isolated commands could not timeout. They now have a timeout registered on another (HystrixTimer) thread, which triggers the timeout flow. If you use semaphore-isolated commands, they will now see timeouts"

Anyway try to:

1. Switch to THREAD isolation with own thread pool.
2. Sleep in cycle with smaller periods.