[GitHub] [spark] WeichenXu123 commented on a change in pull request #24734: [SPARK-27870][SQL][PySpark] Flush each batch for pandas UDF (for improving pandas UDFs pipeline)

[GitBox <gi...@apache.org>]

WeichenXu123 commented on a change in pull request #24734: [SPARK-27870][SQL][PySpark] Flush each batch for pandas UDF (for improving pandas UDFs pipeline)
URL: https://github.com/apache/spark/pull/24734#discussion_r288377915
 
 

 ##########
 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/python/ArrowEvalPythonExec.scala
 ##########
 @@ -86,28 +86,11 @@ case class ArrowEvalPythonExec(udfs: Seq[PythonUDF], resultAttrs: Seq[Attribute]
       sessionLocalTimeZone,
       pythonRunnerConf).compute(batchIter, context.partitionId(), context)
 
-    new Iterator[InternalRow] {
-
-      private var currentIter = if (columnarBatchIter.hasNext) {
-        val batch = columnarBatchIter.next()
-        val actualDataTypes = (0 until batch.numCols()).map(i => batch.column(i).dataType())
-        assert(outputTypes == actualDataTypes, "Invalid schema from pandas_udf: " +
-          s"expected ${outputTypes.mkString(", ")}, got ${actualDataTypes.mkString(", ")}")
-        batch.rowIterator.asScala
-      } else {
-        Iterator.empty
-      }
-
-      override def hasNext: Boolean = currentIter.hasNext || {
-        if (columnarBatchIter.hasNext) {
-          currentIter = columnarBatchIter.next().rowIterator.asScala
-          hasNext
-        } else {
-          false
-        }
-      }
-
-      override def next(): InternalRow = currentIter.next()
+    columnarBatchIter.flatMap { batch =>
+      val actualDataTypes = (0 until batch.numCols()).map(i => batch.column(i).dataType())
+      assert(outputTypes == actualDataTypes, "Invalid schema from pandas_udf: " +
+        s"expected ${outputTypes.mkString(", ")}, got ${actualDataTypes.mkString(", ")}")
+      batch.rowIterator.asScala
 
 Review comment:
   Some explanation here:
   The master impl has an issue,
   the member "private var currentIter = ..." will be computed when create the returned iterator. Computing the `currentIter` require to read the first element of `columnarBatchIter`. But note that this block code being called from `EvalPythonExec.doExecute`, we should not read iterator here, we can only generate iterator. Reading iterator should start after the total iterator pipeline constructed.

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org