pan3793 commented on code in PR #38468:
URL: https://github.com/apache/spark/pull/38468#discussion_r1015733832
##########
connector/connect/src/main/scala/org/apache/spark/sql/connect/service/SparkConnectStreamHandler.scala:
##########
@@ -117,10 +129,91 @@ class SparkConnectStreamHandler(responseObserver:
StreamObserver[Response]) exte
responseObserver.onNext(response.build())
}
- responseObserver.onNext(sendMetricsToResponse(clientId, rows))
+ responseObserver.onNext(sendMetricsToResponse(clientId, dataframe))
responseObserver.onCompleted()
}
+ def processRowsAsArrowBatches(clientId: String, dataframe: DataFrame): Unit
= {
+ val spark = dataframe.sparkSession
+ val schema = dataframe.schema
+ // TODO: control the batch size instead of max records
+ val maxRecordsPerBatch = spark.sessionState.conf.arrowMaxRecordsPerBatch
+ val timeZoneId = spark.sessionState.conf.sessionLocalTimeZone
+
+ SQLExecution.withNewExecutionId(dataframe.queryExecution,
Some("collectArrow")) {
+ val pool =
ThreadUtils.newDaemonSingleThreadExecutor("connect-collect-arrow")
+ val tasks = collection.mutable.ArrayBuffer.empty[Future[_]]
+ val rows = dataframe.queryExecution.executedPlan.execute()
+
+ if (rows.getNumPartitions > 0) {
+ val batches = rows.mapPartitionsInternal { iter =>
+ ArrowConverters
+ .toArrowBatchIterator(iter, schema, maxRecordsPerBatch, timeZoneId)
+ }
+
+ val processPartition = (iter: Iterator[(Array[Byte], Long, Long)]) =>
iter.toArray
+
+ val resultHandler = (partitionId: Int, taskResult: Array[(Array[Byte],
Long, Long)]) => {
+ if (taskResult.exists(_._1.nonEmpty)) {
+ // only send non-empty partitions
+ val task = pool.submit(new Runnable {
+ override def run(): Unit = {
+ var batchId = partitionId.toLong << 33
+ taskResult.foreach { case (bytes, count, size) =>
+ val response =
proto.Response.newBuilder().setClientId(clientId)
+ val batch = proto.Response.ArrowBatch
+ .newBuilder()
+ .setBatchId(batchId)
+ .setRowCount(count)
+ .setUncompressedBytes(size)
+ .setCompressedBytes(bytes.length)
+ .setData(ByteString.copyFrom(bytes))
+ .build()
+ response.setArrowBatch(batch)
+ responseObserver.onNext(response.build())
Review Comment:
If I understand correctly, the `TaskResultGetter` runs in a separate thread
pool, and there is no back pressure mechanism, the current approach still may
cause memory pressure on the driver if the client consumes results slowly.
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