Rx Reactive Streams 可连接 Observable

Question

通读本文档：

https://github.com/ReactiveX/RxJava/wiki/Connectable-Observable-Operators

我有一些关于 Connectable Observables 工作规则的问题！维基上是这么解释的：

The following example code shows two Subscribers subscribing to the same Observable. In the first case, they subscribe to an ordinary Observable; in the second case, they subscribe to a Connectable Observable that only connects after both Subscribers subscribe. Note the difference in the output: 

Example #1:

def firstMillion  = Observable.range( 1, 1000000 ).sample(7, java.util.concurrent.TimeUnit.MILLISECONDS);

firstMillion.subscribe(
   { println("Subscriber #1:" + it); },       // onNext
   { println("Error: " + it.getMessage()); }, // onError
   { println("Sequence #1 complete"); }       // onCompleted
);

firstMillion.subscribe(
    { println("Subscriber #2:" + it); },       // onNext
    { println("Error: " + it.getMessage()); }, // onError
    { println("Sequence #2 complete"); }       // onCompleted
);
Subscriber #1:211128
Subscriber #1:411633
Subscriber #1:629605
Subscriber #1:841903
Sequence #1 complete
Subscriber #2:244776
Subscriber #2:431416
Subscriber #2:621647
Subscriber #2:826996
Sequence #2 complete

Example #2:

def firstMillion  = Observable.range( 1, 1000000 ).sample(7, java.util.concurrent.TimeUnit.MILLISECONDS).publish();

firstMillion.subscribe(
   { println("Subscriber #1:" + it); },       // onNext
   { println("Error: " + it.getMessage()); }, // onError
   { println("Sequence #1 complete"); }       // onCompleted
);

firstMillion.subscribe(
   { println("Subscriber #2:" + it); },       // onNext
   { println("Error: " + it.getMessage()); }, // onError
   { println("Sequence #2 complete"); }       // onCompleted
);

firstMillion.connect();
Subscriber #2:208683
Subscriber #1:208683
Subscriber #2:432509
Subscriber #1:432509
Subscriber #2:644270
Subscriber #1:644270
Subscriber #2:887885
Subscriber #1:887885
Sequence #2 complete
Sequence #1 complete

我没有得到的是以下内容：

在示例 #2 中，Observable 如何知道有两个订阅者（在这种情况下）
如何处理其中一个订阅者速度慢的场景。

Answer 1

回答您的第一个问题：因为对 subscribe 进行了两次调用。

回答你的第二个问题：如果这是一个问题，你需要对观察者应用一些背压算法，这可能会很慢。

RxJS 存储库对 RxJS 中可用的一些背压选项有 good introduction。我不确定 RxJava 中有多少提到的运算符。我知道他们中的一些人这样做。

Rx Reactive Streams 可连接 Observable

Rx Reactive Streams Connectable Observables

java

scala

reactive-programming

subscription

observable