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From: BryanCutler <git@git.apache.org>
To: reviews@spark.apache.org
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References: <git-pr-18659-spark@git.apache.org>
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Subject: [GitHub] spark pull request #18659: [SPARK-21190][PYSPARK][WIP] Simple Python Vectori...
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Message-Id: <20170906230326.3ECE7E08F6@git1-us-west.apache.org>
Date: Wed,  6 Sep 2017 23:03:25 +0000 (UTC)
archived-at: Wed, 06 Sep 2017 23:03:28 -0000

Github user BryanCutler commented on a diff in the pull request:

    https://github.com/apache/spark/pull/18659#discussion_r137412019
  
    --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/python/ArrowEvalPythonExec.scala ---
    @@ -0,0 +1,127 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one or more
    + * contributor license agreements.  See the NOTICE file distributed with
    + * this work for additional information regarding copyright ownership.
    + * The ASF licenses this file to You under the Apache License, Version 2.0
    + * (the "License"); you may not use this file except in compliance with
    + * the License.  You may obtain a copy of the License at
    + *
    + *    http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +package org.apache.spark.sql.execution.python
    +
    +import java.io.File
    +
    +import scala.collection.mutable.ArrayBuffer
    +
    +import org.apache.spark.{SparkEnv, TaskContext}
    +import org.apache.spark.api.python.{ChainedPythonFunctions, PythonEvalType, PythonRunner}
    +import org.apache.spark.rdd.RDD
    +import org.apache.spark.sql.catalyst.InternalRow
    +import org.apache.spark.sql.catalyst.expressions._
    +import org.apache.spark.sql.execution.SparkPlan
    +import org.apache.spark.sql.execution.arrow.{ArrowConverters, ArrowPayload}
    +import org.apache.spark.sql.types.{DataType, StructField, StructType}
    +import org.apache.spark.util.Utils
    +
    +
    +/**
    + * A physical plan that evaluates a [[PythonUDF]],
    + */
    +case class ArrowEvalPythonExec(udfs: Seq[PythonUDF], output: Seq[Attribute], child: SparkPlan)
    +  extends SparkPlan {
    +
    +  def children: Seq[SparkPlan] = child :: Nil
    +
    +  override def producedAttributes: AttributeSet = AttributeSet(output.drop(child.output.length))
    +
    +  private def collectFunctions(udf: PythonUDF): (ChainedPythonFunctions, Seq[Expression]) = {
    +    udf.children match {
    +      case Seq(u: PythonUDF) =>
    +        val (chained, children) = collectFunctions(u)
    +        (ChainedPythonFunctions(chained.funcs ++ Seq(udf.func)), children)
    +      case children =>
    +        // There should not be any other UDFs, or the children can't be evaluated directly.
    +        assert(children.forall(_.find(_.isInstanceOf[PythonUDF]).isEmpty))
    +        (ChainedPythonFunctions(Seq(udf.func)), udf.children)
    +    }
    +  }
    +
    +  protected override def doExecute(): RDD[InternalRow] = {
    +    val inputRDD = child.execute().map(_.copy())
    +    val bufferSize = inputRDD.conf.getInt("spark.buffer.size", 65536)
    +    val reuseWorker = inputRDD.conf.getBoolean("spark.python.worker.reuse", defaultValue = true)
    +
    +    inputRDD.mapPartitions { iter =>
    +
    +      // The queue used to buffer input rows so we can drain it to
    +      // combine input with output from Python.
    +      val queue = HybridRowQueue(TaskContext.get().taskMemoryManager(),
    +        new File(Utils.getLocalDir(SparkEnv.get.conf)), child.output.length)
    +      TaskContext.get().addTaskCompletionListener({ ctx =>
    +        queue.close()
    +      })
    +
    +      val (pyFuncs, inputs) = udfs.map(collectFunctions).unzip
    +
    +      // flatten all the arguments
    +      val allInputs = new ArrayBuffer[Expression]
    +      val dataTypes = new ArrayBuffer[DataType]
    +      val argOffsets = inputs.map { input =>
    +        input.map { e =>
    +          if (allInputs.exists(_.semanticEquals(e))) {
    +            allInputs.indexWhere(_.semanticEquals(e))
    +          } else {
    +            allInputs += e
    +            dataTypes += e.dataType
    +            allInputs.length - 1
    +          }
    +        }.toArray
    +      }.toArray
    +      val projection = newMutableProjection(allInputs, child.output)
    +      val schema = StructType(dataTypes.zipWithIndex.map { case (dt, i) =>
    +        StructField(s"_$i", dt)
    +      })
    +
    +      // Input iterator to Python: input rows are grouped so we send them in batches to Python.
    +      // For each row, add it to the queue.
    +      val projectedRowIter = iter.map { inputRow =>
    +        queue.add(inputRow.asInstanceOf[UnsafeRow])
    +        projection(inputRow)
    +      }
    +
    +      val context = TaskContext.get()
    +
    +      val inputIterator = ArrowConverters.toPayloadIterator(
    +          projectedRowIter, schema, conf.arrowMaxRecordsPerBatch, context).
    +        map(_.asPythonSerializable)
    +
    +      val schemaOut = StructType.fromAttributes(output.drop(child.output.length).zipWithIndex.
    +        map { case (attr, i) => attr.withName(s"_$i") })
    +
    +      // Output iterator for results from Python.
    +      val outputIterator = new PythonRunner(
    +          pyFuncs, bufferSize, reuseWorker, PythonEvalType.SQL_ARROW_UDF, argOffsets).
    +        compute(inputIterator, context.partitionId(), context)
    +
    +      val joined = new JoinedRow
    +      val resultProj = UnsafeProjection.create(output, output)
    +
    +      val outputRowIterator = ArrowConverters.fromPayloadIterator(
    +        outputIterator.map(new ArrowPayload(_)), context)
    +
    +      assert(schemaOut.equals(outputRowIterator.schema))
    --- End diff --
    
    @felixcheung , I think you had also brought up checking the return type matches what was defined in the UDF.  This is done here.


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