Multithreading rx java在多个不同线程上运行可观察到

我是RXJava新手，所以我可能缺少一些非常基本的东西。在下面的代码示例中，我希望发生的是：

SampleController在http nio线程上接收请求

CompositeService处理在新线程a上运行，并释放nio请求线程

CompositeService调用HelloService，HelloService在线程B上进行网络调用

CompositeService调用WorldService，后者在线程C上进行网络调用

3和4同时运行，当结果就绪时，我们使用结果对线程a进行网络调用

相反，我看到的是3和4在http nio线程上顺序执行，只有CompositeService在新线程上执行。我在3和4中的subscribeOn调用似乎没有任何效果。如何使3和4同时运行

采样控制器：

@RestController
@RequestMapping("/rx-java-sample")
public class SampleController {

    private static Logger log = LoggerFactory.getLogger(SampleController.class);

    @Autowired
    private CompositeService compositeService;

    @RequestMapping(method = RequestMethod.GET, 
        produces = { MediaType.APPLICATION_JSON_VALUE })
    public DeferredResult<String> getCompositeString() 
                    throws ApiGatewayException, ApiValidationException {
        log.info("Received getCompositeObject request");

        Observable<String> compositeObject = compositeService.getCompositeString();

        return toDeferredResult(compositeObject);
    }

    private DeferredResult<String> toDeferredResult(Observable<String> compositeObject) {
        DeferredResult<String> result = new DeferredResult<String>();

        compositeObject.subscribeOn(Schedulers.newThread()).subscribe(new Observer<String>() {
            @Override
            public void onCompleted() {
            }

            @Override
            public void onError(Throwable throwable) {
                result.setErrorResult(throwable);
            }

            @Override
            public void onNext(String compositeString) {
                log.info("Returning compositeObject: " + compositeString);
                result.setResult(compositeString);
            }
        });

        return result;
    }
}

@Service
public class HelloService {

    private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getHello() {
        log.trace("calling get hello");
        return Observable.just(makeNetworkCall());
    }

    private String makeNetworkCall() {
        log.trace("making hello network call");
        return "hello";
    }
}

---

问题似乎是我使用了Observable.just而不是Observable.fromCallable。从上面如下修改服务代码产生了我想要的行为。我仍然在寻找反馈，看这是否是“推荐”的方法。特别是，我不确定在CompositeService中使用Toblock（）是否正确。我可能会在我的代码中广泛使用这种模式，我希望它正确

HelloService：

@Service
public class WorldService {

private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getWorld() {
        log.trace("calling get world");
        return Observable.just(makeNetworkCall());
    }

    private String makeNetworkCall() {
        log.trace("making world network call");
        return "world";
    }
}

@Service
public class CompositeService {

    private Logger log = LoggerFactory.getLogger(CompositeService.class);

    @Autowired
    private HelloService helloService;

    @Autowired
    private WorldService worldService;

    public Observable<String> getCompositeString() {
        log.trace("Calling getCompositeObject");

        Observable<String> foo = helloService.getHello().subscribeOn(Schedulers.newThread());
        Observable<String> bar = worldService.getWorld().subscribeOn(Schedulers.newThread());

        return Observable.zip(foo, bar, (f, b) -> makeNetworkCall(f,b));
    }

    private String makeNetworkCall(String hello, String world) {
        log.trace("making composite network call");
        return hello + " " +  world;
    }
}

2016-06-16 07:10:13 INFO [http-nio-9050-exec-1] [SampleController.java:32] Received getCompositeObject request
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [CompositeService.java:23] Calling getCompositeObject
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [HelloService.java:15] calling get hello
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [HelloService.java:20] making hello network call
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [WorldService.java:15] calling get world
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [WorldService.java:20] making world network call
2016-06-16 07:10:13 TRACE [RxNewThreadScheduler-3] [CompositeService.java:32] making composite network call
2016-06-16 07:10:13 INFO [RxNewThreadScheduler-3] [SampleController.java:54] Returning compositeObject: hello world

@Service
public class HelloService {

    private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getHello() {
        log.trace("calling get hello");

        return Observable.fromCallable(() -> { 
            return makeNetworkCall();
        });
    }

    private String makeNetworkCall() {
        log.trace("making hello network call");
        return "hello";
    }
}

@Service
public class WorldService {

private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getWorld() {
        log.trace("calling get world");

        return Observable.fromCallable(() -> { 
            return makeNetworkCall();
        });
    }

    private String makeNetworkCall() {
        log.trace("making world network call");
        return "world";
    }
}

2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-1] [CompositeService.java:29] Calling getCompositeObject
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-1] [HelloService.java:15] calling get hello
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-1] [WorldService.java:15] calling get world
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-2] [HelloService.java:23] making hello network call
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-3] [WorldService.java:23] making world network call
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-3] [CompositeService.java:38] making composite network call
2016-06-16 08:15:50 INFO [RxNewThreadScheduler-1] [SampleController.java:54] Returning compositeObject: hello world

日志：

@Service
public class WorldService {

private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getWorld() {
        log.trace("calling get world");
        return Observable.just(makeNetworkCall());
    }

    private String makeNetworkCall() {
        log.trace("making world network call");
        return "world";
    }
}

@Service
public class CompositeService {

    private Logger log = LoggerFactory.getLogger(CompositeService.class);

    @Autowired
    private HelloService helloService;

    @Autowired
    private WorldService worldService;

    public Observable<String> getCompositeString() {
        log.trace("Calling getCompositeObject");

        Observable<String> foo = helloService.getHello().subscribeOn(Schedulers.newThread());
        Observable<String> bar = worldService.getWorld().subscribeOn(Schedulers.newThread());

        return Observable.zip(foo, bar, (f, b) -> makeNetworkCall(f,b));
    }

    private String makeNetworkCall(String hello, String world) {
        log.trace("making composite network call");
        return hello + " " +  world;
    }
}

2016-06-16 07:10:13 INFO [http-nio-9050-exec-1] [SampleController.java:32] Received getCompositeObject request
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [CompositeService.java:23] Calling getCompositeObject
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [HelloService.java:15] calling get hello
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [HelloService.java:20] making hello network call
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [WorldService.java:15] calling get world
2016-06-16 07:10:13 TRACE [http-nio-9050-exec-1] [WorldService.java:20] making world network call
2016-06-16 07:10:13 TRACE [RxNewThreadScheduler-3] [CompositeService.java:32] making composite network call
2016-06-16 07:10:13 INFO [RxNewThreadScheduler-3] [SampleController.java:54] Returning compositeObject: hello world

@Service
public class HelloService {

    private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getHello() {
        log.trace("calling get hello");

        return Observable.fromCallable(() -> { 
            return makeNetworkCall();
        });
    }

    private String makeNetworkCall() {
        log.trace("making hello network call");
        return "hello";
    }
}

@Service
public class WorldService {

private Logger log = LoggerFactory.getLogger(HelloService.class);

    public Observable<String> getWorld() {
        log.trace("calling get world");

        return Observable.fromCallable(() -> { 
            return makeNetworkCall();
        });
    }

    private String makeNetworkCall() {
        log.trace("making world network call");
        return "world";
    }
}

2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-1] [CompositeService.java:29] Calling getCompositeObject
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-1] [HelloService.java:15] calling get hello
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-1] [WorldService.java:15] calling get world
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-2] [HelloService.java:23] making hello network call
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-3] [WorldService.java:23] making world network call
2016-06-16 08:15:50 TRACE [RxNewThreadScheduler-3] [CompositeService.java:38] making composite network call
2016-06-16 08:15:50 INFO [RxNewThreadScheduler-1] [SampleController.java:54] Returning compositeObject: hello world

---

您希望对以下情况使用

Observable:：defer

：

  public Observable<String> getWorld() {
      log.trace("calling get world");

      return Observable.defer(() -> makeNetworkCall());
  }

publicobservable getWorld（）{
trace（“调用get world”）；
return Observable.defer（（）->makeNetworkCall（））；
}

这确保了每次在可观察对象上进行重写时都会调用代码

---

另外，我建议使用

Schedulers.io（）

；它是一个可配置的线程池，默认情况下可根据需要扩展。

fyi，cpu绑定的工作有Schedulers.computation（），io绑定的工作有Schedulers.io（），通常比Schedulers.newThread（）更好。