[英]How do I use infinite Scala streams as source in Spark Streaming?
假设我基本上希望Stream.from(0)
作为InputDStream
。 我该怎么做? 我能看到的唯一方法是使用StreamingContext#queueStream
,但是我必须从另一个线程或子类Queue
排队元素以创建一个行为类似于无限流的队列,这两者都感觉像是一个黑客。
这样做的正确方法是什么?
我不认为默认情况下它在Spark中可用,但使用ReceiverInputDStream很容易实现它。
import org.apache.spark.storage.StorageLevel
import org.apache.spark.streaming.StreamingContext
import org.apache.spark.streaming.dstream.ReceiverInputDStream
import org.apache.spark.streaming.receiver.Receiver
class InfiniteStreamInputDStream[T](
@transient ssc_ : StreamingContext,
stream: Stream[T],
storageLevel: StorageLevel
) extends ReceiverInputDStream[T](ssc_) {
override def getReceiver(): Receiver[T] = {
new InfiniteStreamReceiver(stream, storageLevel)
}
}
class InfiniteStreamReceiver[T](stream: Stream[T], storageLevel: StorageLevel) extends Receiver[T](storageLevel) {
// Stateful iterator
private val streamIterator = stream.iterator
private class ReadAndStore extends Runnable {
def run(): Unit = {
while (streamIterator.hasNext) {
val next = streamIterator.next()
store(next)
}
}
}
override def onStart(): Unit = {
new Thread(new ReadAndStore).run()
}
override def onStop(): Unit = { }
}
稍微修改过的代码与Spark 2.0一起使用:
import org.apache.spark.storage.StorageLevel
import org.apache.spark.streaming.StreamingContext
import org.apache.spark.streaming.dstream.ReceiverInputDStream
import org.apache.spark.streaming.receiver.Receiver
import scala.reflect.ClassTag
class InfiniteDStream[T: ClassTag](
@transient ssc_ : StreamingContext,
stream: Stream[T],
storageLevel: StorageLevel
) extends ReceiverInputDStream[T](ssc_) {
override def getReceiver(): Receiver[T] = {
new InfiniteStreamReceiver(stream, storageLevel)
}
}
class InfiniteStreamReceiver[T](stream: Stream[T], storageLevel: StorageLevel) extends Receiver[T](storageLevel) {
private class ReadAndStore extends Runnable {
def run(): Unit = {
stream.foreach(store)
}
}
override def onStart(): Unit = {
val t = new Thread(new ReadAndStore)
t.setDaemon(true)
t.run()
}
override def onStop(): Unit = {}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.