我略加修改的例子 - https://github.com/apache/spark/blob/v2.2.0/examples/src/main/scala/org/apache/spark/examples/sql/streaming/StructuredNetworkWordCount.scala星火结构化数据流,多次查询无法运行,从这里拍摄同时
我加秒writeStream(片):
scala
case class MyWriter1() extends ForeachWriter[Row]{
override def open(partitionId: Long, version: Long): Boolean = true
override def process(value: Row): Unit = {
println(s"custom1 - ${value.get(0)}")
}
override def close(errorOrNull: Throwable): Unit = true
}
case class MyWriter2() extends ForeachWriter[(String, Int)]{
override def open(partitionId: Long, version: Long): Boolean = true
override def process(value: (String, Int)): Unit = {
println(s"custom2 - $value")
}
override def close(errorOrNull: Throwable): Unit = true
}
object Main extends Serializable{
def main(args: Array[String]): Unit = {
println("starting")
Logger.getLogger("org").setLevel(Level.OFF)
Logger.getLogger("akka").setLevel(Level.OFF)
val host = "localhost"
val port = "9999"
val spark = SparkSession
.builder
.master("local[*]")
.appName("app-test")
.getOrCreate()
import spark.implicits._
// Create DataFrame representing the stream of input lines from connection to host:port
val lines = spark.readStream
.format("socket")
.option("host", host)
.option("port", port)
.load()
// Split the lines into words
val words = lines.as[String].flatMap(_.split(" "))
// Generate running word count
val wordCounts = words.groupBy("value").count()
// Start running the query that prints the running counts to the console
val query1 = wordCounts.writeStream
.outputMode("update")
.foreach(MyWriter1())
.start()
val ds = wordCounts.map(x => (x.getAs[String]("value"), x.getAs[Int]("count")))
val query2 = ds.writeStream
.outputMode("update")
.foreach(MyWriter2())
.start()
spark.streams.awaitAnyTermination()
}
}
遗憾的是,只有第一个查询运行,第二从不(MyWriter2从未被称为)
请指教我做错了什么。根据doc:您可以在单个SparkSession中启动任意数量的查询。他们将全部同时运行共享群集资源。
不幸的是它不。只有query1运行。所以我注意到的是:该查询首先启动。还有什么我应该注意的吗? –
运行应用程序时会发生什么?它是否在第二个查询运行之前终止?显然你必须删除'awaitAnyTermination' – raam86
我删除了awaitAnyTermination和两个查询使用awaitTermination(实际上我已经尝试了所有可能的选项,包括Thread.sleep ...);应用程序不终止,它保持运行并从套接字接收数据;但每次有新数据出现时,只有第一个查询会触发。 –