RxJava2.1.0：在不同线程上订阅时未调用PublishSubject onNext

Question

我们发现，在调用主题上的onNext事件后10-20 ms内订阅序列化PublishSubject时；未调用新订阅者的onNext。

在下面的代码片段中；要观察的值[1]被给出为“2000”，并且在使用值为1998[2]的主题上调用onNext（）后调用订阅对象（）；我们看到，如果间隔为10ms，新订阅者将错过主题触发的值2000；然而，如果间隔为50ms或更大，那么新订阅者似乎会收到预期值；这是预期行为吗？

这种行为可以在RxJava 2.1.0上看到；似乎是某种种族状况

public class PublishSubjectTest {

    private final Subject<String> singlePropertyUpdateSubject =
            PublishSubject.<String>create().toSerialized();


    public static void main(String[] args) {
        PublishSubjectTest obj= new PublishSubjectTest();
        obj.sendEvents();
        try {
            Thread.currentThread().join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }


//[1]
    private final String valueToObserve = "2000";
    private void subscribeToSubject() {
        System.out.println("Subscribing .....");
        io.reactivex.Observable.range(1,10).subscribeOn(Schedulers.newThread()).subscribe(
                value -> getAndObserve(valueToObserve).subscribe(observedValue -> System.out.println("  Value Received   "+observedValue +" By "+Thread.currentThread() ))
        );



    }

    private io.reactivex.Observable<String> getAndObserve(String value) {
        final io.reactivex.Observable<String> observable = singlePropertyUpdateSubject
                //.doOnNext(v-> System.out.println("Received value "+v))
                .filter(v -> v.equals(value))
                .doOnSubscribe(c-> System.out.println("Consumer subscribed "+c));
        return observable;
    }


// 50ms >= expected result ;  Anything less than 10ms will fail.
    private void sendEvents() {
        io.reactivex.Observable.interval(10, TimeUnit.MILLISECONDS).subscribe(value -> {
            String key = value.toString();
            //System.out.println("Adding key "+key);
            singlePropertyUpdateSubject.onNext(key);
//[2]           
 if (value == 1998){
                subscribeToSubject();;
            }
            if (value%100==0) {
                System.out.println(value);
            }

        });
    }

Answer 1

好的，问题是PublishSubject；使用ReplaySubject似乎可以解决并发订阅的问题；测试代码调用系统也存在问题。使用ReplaySubject时退出（1）；github提供了详细的讨论。com/ReactiveX/RxJava/issues/6414–

请将此问题视为已解决。