Monix:InputStreamObservable不支持多个订阅者

时间:2018-02-07 06:04:43

标签: scala reactive-programming monix

我正在尝试将一个Observable(String,Date)拆分为两个不同的Observable并将它们压缩在一起,如下所示

import monix.execution.Scheduler.Implicits.global
val x = Observable.fromIterator((0 to 10).map(i => (s"a $i", s"b $i")).toIterator)

val y = Observable.toReactive(x)

val fileStream = Observable.fromReactivePublisher(y).mapAsync(5)(a => Task{println(a._1); a._1})
val dateStream = Observable.fromReactivePublisher(y).mapAsync(5)(a => Task{println(a._2); a._2})

fileStream.zip(dateStream)
  .map(println)
  .subscribe()

但是我得到了以下异常

monix.reactive.exceptions.MultipleSubscribersException: InputStreamObservable does not support multiple subscribers
    at monix.reactive.exceptions.MultipleSubscribersException$.build(MultipleSubscribersException.scala:51)
    at monix.reactive.internal.builders.IteratorAsObservable.unsafeSubscribeFn(IteratorAsObservable.scala:42)
    at monix.reactive.Observable$$anon$6.subscribe(Observable.scala:155)
    at monix.reactive.internal.builders.ReactiveObservable.unsafeSubscribeFn(ReactiveObservable.scala:38)
    at monix.reactive.internal.operators.MapAsyncParallelObservable.unsafeSubscribeFn(MapAsyncParallelObservable.scala:60)
    at monix.reactive.internal.builders.Zip2Observable.unsafeSubscribeFn(Zip2Observable.scala:158)
    at monix.reactive.Observable$$anon$5.unsafeSubscribeFn(Observable.scala:139)
    at monix.reactive.Observable$class.subscribe(Observable.scala:71)
    at monix.reactive.Observable$$anon$5.subscribe(Observable.scala:136)
    at monix.reactive.Observable$class.subscribe(Observable.scala:90)
    at monix.reactive.Observable$$anon$5.subscribe(Observable.scala:136)
    at monix.reactive.Observable$class.subscribe(Observable.scala:120)
    at monix.reactive.Observable$$anon$5.subscribe(Observable.scala:136)
    at monix.reactive.Observable$class.subscribe(Observable.scala:112)
    at monix.reactive.Observable$$anon$5.subscribe(Observable.scala:136)

2 个答案:

答案 0 :(得分:2)

转换为/来自被动是必须的吗?

解决问题的一种方法是val x = Observable.fromIterable((0 to 10).map(i => (s"a $i", s"b $i"))),但对于无限流,它会出现OutOfMemoryError。

另一种方法是使用.multicast(Pipe.publish[]),然后使用obs.connect()代码:

import monix.execution.Scheduler.Implicits.global
val x = Observable.fromIterator((0 to 10).map(i => (s"a $i", s"b $i")).iterator)

val y = Observable.toReactive(x)
val obsY = Observable.fromReactivePublisher(y)
val connectY = obsY.multicast(Pipe.publish[(String, String)])

val fileStream = connectY.mapAsync(5)(a => Task{println(a._1); a._1})
val dateStream = connectY.mapAsync(5)(a => Task{println(a._2); a._2})

fileStream.zip(dateStream)
  .map(println)
  .subscribe()

connectY.connect()

Thread.sleep(5000)

答案 1 :(得分:0)

除了sergei-shubin的回答外,还可以将Observable临时转换为“热”可观察对象,可以使用publishSelector将其拆分为多个流,而无需手动处理{{1 }}。看起来像这样:

multicast