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[英]In Spark Structured streaming with Kafka, how spark manages offset for multiple topics
[英]spark streaming join kafka topics
我們有兩個Kafka主題中的兩個InputDStream
,但是我們必須將這兩個輸入的數據連接在一起。 問題是,每個InputDStream
獨立處理,因為的foreachRDD
,可以返回什么,給join
后。
var Message1ListBuffer = new ListBuffer[Message1]
var Message2ListBuffer = new ListBuffer[Message2]
inputDStream1.foreachRDD(rdd => {
if (!rdd.partitions.isEmpty) {
val offsetRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges
rdd.map({ msg =>
val r = msg.value()
val avro = AvroUtils.objectToAvro(r.getSchema, r)
val messageValue = AvroInputStream.json[FMessage1](avro.getBytes("UTF-8")).singleEntity.get
Message1ListBuffer = Message1FlatMapper.flatmap(messageValue)
Message1ListBuffer
})
inputDStream1.asInstanceOf[CanCommitOffsets].commitAsync(offsetRanges)
}
})
inputDStream2.foreachRDD(rdd => {
if (!rdd.partitions.isEmpty) {
val offsetRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges
rdd.map({ msg =>
val r = msg.value()
val avro = AvroUtils.objectToAvro(r.getSchema, r)
val messageValue = AvroInputStream.json[FMessage2](avro.getBytes("UTF-8")).singleEntity.get
Message2ListBuffer = Message1FlatMapper.flatmap(messageValue)
Message2ListBuffer
})
inputDStream2.asInstanceOf[CanCommitOffsets].commitAsync(offsetRanges)
}
})
我以為我可以返回Message1ListBuffer和Message2ListBuffer,將它們轉換為數據幀並加入它們。 但這是行不通的,我認為這不是最佳選擇
從那里,返回每個foreachRDD的rdd以便進行聯接的方法是什么?
inputDStream1.foreachRDD(rdd => {
})
inputDStream2.foreachRDD(rdd => {
})
不確定您使用的Spark版本是否為Spark 2.3+,可以直接實現。
val ds1 = spark
.readStream
.format("kafka")
.option("kafka.bootstrap.servers", "brokerhost1:port1,brokerhost2:port2")
.option("subscribe", "source-topic1")
.option("startingOffsets", "earliest")
.option("endingOffsets", "latest")
.load
val ds2 = spark
.readStream
.format("kafka")
.option("kafka.bootstrap.servers", "brokerhost1:port1,brokerhost2:port2")
.option("subscribe", "source-topic2")
.option("startingOffsets", "earliest")
.option("endingOffsets", "latest")
.load
val stream1 = ds1.selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
.as[(String, String)]
val stream2 = ds2.selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
.as[(String, String)]
resultStream = stream1.join(stream2)
警告:
延遲記錄將不會獲得聯接匹配。 需要調整緩沖一點。 在這里找到更多信息
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