超时如何在 Hystrix 中与 Observables 一起工作？

Question

我正在使用 Reactive Observables 开发支持 Hystrix 的 Spring Boot-app，并试图弄清楚超时是如何工作的。我假设如果在执行期间发生超时，Hystrix 会立即 return 响应（回退或异常）。现在，鉴于我下面的代码，情况似乎并非如此。相反，对 myService.getString() 的调用会阻塞 5 秒。当它最终 returns 时，throwable lambda 被执行。

是我的假设不正确还是下面有其他错误？

@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>

感谢您的帮助！

Answer 1

请说明您的 hystrix 命令的隔离是什么以及您使用的是什么版本的 hystrix？

"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"

无论如何尝试：

使用自己的线程池切换到 THREAD 隔离。
以更短的周期睡眠。

Answer 2

将 execution.isolation.strategy 设置为 THREAD 解决了我的问题。

@HystrixCommand(
  commandProperties = {
    @HystrixProperty(name = "execution.isolation.strategy", value = "THREAD")
  }
)

文档指出 HystrixCommand 默认使用 THREAD 但它与 javanica @HystrixCommand 有点不同，它根据注释方法的 return 类型创建不同的类型。 HystrixCommand 或 HystrixObservableCommand。 HystrixObservableCommand 将 SEMAPHORE 作为默认隔离策略。

有关详细信息，请参阅 https://github.com/Netflix/Hystrix/issues/1383。

超时如何在 Hystrix 中与 Observables 一起工作？

How do timeouts work in Hystrix with Observables?

java

rx-java

spring-boot

hystrix