Flink KeyedCoProcessFunction 处理状态

Question

我使用 keyedCoprocessfunction 函数用数据丰富了主数据流，来自另一个流

代码：

class AssetDataEnrichment extends KeyedCoProcessFunction[String, PacketData, AssetCommandState, AssetData] with LazyLogging {

  case class AssetStateDoc(assetId: Option[String])
  private var associatedDevices: ValueState[AssetStateDoc] = _

  override def open(parameters: Configuration): Unit = {
    val associatedDevicesDescriptor =
      new ValueStateDescriptor[AssetStateDoc]("associatedDevices", classOf[AssetStateDoc])
    associatedDevices = getRuntimeContext.getState[AssetStateDoc](associatedDevicesDescriptor)
  }

  override def processElement1(
                                packet: PacketData,
                                ctx: KeyedCoProcessFunction[String, PacketData, AssetCommandState, AssetData]#Context,
                                out: Collector[AssetData]): Unit = {
    
    val tmpState = associatedDevices.value
    val state = if (tmpState == null) AssetStateDoc(None) else tmpState
    
    state.assetId match {
      case Some(assetId) =>
        logger.debug(s"There are state for ${packet.tag.externalId} = $assetId")
        out.collect(AssetData(assetId, packet.tag.externalId.get, packet.toString))
      case None => logger.debug(s"No state for a packet ${packet.tag.externalId}")
      case _ => logger.debug("Smth went wrong")
    }
  }

  override def processElement2(
                                value: AssetCommandState,
                                ctx: KeyedCoProcessFunction[String, PacketData, AssetCommandState, AssetData]#Context,
                                out: Collector[AssetData]): Unit = {
    
    value.command match {
      case CREATE =>
        logger.debug(s"Got command to CREATE state for tag: ${value.id} with value: ${value.assetId}")
        logger.debug(s"current state is ${associatedDevices.value()}")
        associatedDevices.update(AssetStateDoc(Some(value.assetId)))
        logger.debug(s"new state is ${associatedDevices.value()}")
      case _ =>
        logger.error("Got unknown AssetCommandState command")
    }
  }
}

processElement2（）效果很好，它是接受数据并更新状态。


但是在 processElement1（）中，我总是击中 case none =＆gt; 对于数据包$ {packet.tag.externalId}”）

logger.debug（s“无状态，

>我使用了本指南 - https://nightlies.apache.org/flink/flink/flink-docs-master/docs/dev/datastream/fault-tolerance/state/

Answer 1

processElement1 和 processElement2 确实共享状态，但请记住，这是关键分区状态。这意味着 ProcessElement2 中设置的值时，处理给定值 v2 时，仅在 processElement1 中看到它以稍后使用值< em> v1 具有与 v2 相同的密钥。

还要记住，您无法控制 ProcessElement1 和 ProcessElement2 之间的两个流之间的比赛条件。

ridesandfares练习来自官方的apache flink训练。关于学习与API的这一部分合作。 是相应教程的家。