Github user tejasapatil commented on a diff in the pull request: https://github.com/apache/spark/pull/14702#discussion_r78114829 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/script/ScriptTransformationExec.scala --- @@ -0,0 +1,313 @@ +/* + * 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.script + +import java.io._ +import java.nio.charset.StandardCharsets + +import scala.collection.JavaConverters._ +import scala.util.control.NonFatal + +import org.apache.hadoop.conf.Configuration + +import org.apache.spark.{SparkException, TaskContext} +import org.apache.spark.internal.Logging +import org.apache.spark.rdd.RDD +import org.apache.spark.sql.SQLContext +import org.apache.spark.sql.catalyst.{CatalystTypeConverters, InternalRow} +import org.apache.spark.sql.catalyst.expressions._ +import org.apache.spark.sql.catalyst.plans.logical.ScriptInputOutputSchema +import org.apache.spark.sql.execution.{SparkPlan, UnaryExecNode} +import org.apache.spark.sql.types.{DataType, StructType} +import org.apache.spark.util.{CircularBuffer, RedirectThread, SerializableConfiguration, Utils} + +/** + * Transforms the input by forking and running the specified script. + * + * @param input the set of expression that should be passed to the script. + * @param script the command that should be executed. + * @param output the attributes that are produced by the script. + */ +private[sql] +case class ScriptTransformationExec( + input: Seq[Expression], + script: String, + output: Seq[Attribute], + child: SparkPlan, + ioschema: ScriptTransformIOSchema) + extends UnaryExecNode with ScriptTransformBase { + + override def producedAttributes: AttributeSet = outputSet -- inputSet + + protected override def doExecute(): RDD[InternalRow] = + execute(sqlContext, child, schema) + + override def processIterator( + inputIterator: Iterator[InternalRow], + hadoopConf: Configuration) : Iterator[InternalRow] = { + + val (proc, inputStream, outputStream, stderrBuffer, outputProjection) = + init(input, script, child) + + // This new thread will consume the ScriptTransformation's input rows and write them to the + // external process. That process's output will be read by this current thread. + val writerThread = new ScriptTransformationWriterThread( + inputIterator, + input.map(_.dataType), + outputProjection, + ioschema, + outputStream, + proc, + stderrBuffer, + TaskContext.get(), + hadoopConf + ) + + val reader = createReader(inputStream) + + val outputIterator: Iterator[InternalRow] = new Iterator[InternalRow] { + var curLine: String = null + val mutableRow = new SpecificMutableRow(output.map(_.dataType)) + + override def hasNext: Boolean = { + try { + if (curLine == null) { + curLine = reader.readLine() + if (curLine == null) { + checkFailureAndPropagate(writerThread.exception, null, proc, stderrBuffer) + return false + } + } + true + } catch { + case NonFatal(e) => + // If this exception is due to abrupt / unclean termination of `proc`, + // then detect it and propagate a better exception message for end users + checkFailureAndPropagate(writerThread.exception, e, proc, stderrBuffer) + + throw e + } + } + + override def next(): InternalRow = { + if (!hasNext) { + throw new NoSuchElementException + } + val prevLine = curLine + curLine = reader.readLine() + if (!ioschema.isSchemaLess) { + new GenericInternalRow( + prevLine.split(ioschema.outputRowFormatMap("TOK_TABLEROWFORMATFIELD")) + .map(CatalystTypeConverters.convertToCatalyst)) + } else { + new GenericInternalRow( + prevLine.split(ioschema.outputRowFormatMap("TOK_TABLEROWFORMATFIELD"), 2) + .map(CatalystTypeConverters.convertToCatalyst)) + } + } + } + + writerThread.start() + outputIterator + } +} + +private[sql] trait ScriptTransformBase extends Serializable with Logging { + + def init(input: Seq[Expression], + script: String, + child: SparkPlan + ): (Process, InputStream, OutputStream, CircularBuffer, InterpretedProjection) = { + + val cmd = List("/bin/bash", "-c", script) + val builder = new ProcessBuilder(cmd.asJava) + + val proc = builder.start() + val inputStream = proc.getInputStream + val outputStream = proc.getOutputStream + val errorStream = proc.getErrorStream + + // In order to avoid deadlocks, we need to consume the error output of the child process. + // To avoid issues caused by large error output, we use a circular buffer to limit the amount + // of error output that we retain. See SPARK-7862 for more discussion of the deadlock / hang + // that motivates this. + val stderrBuffer = new CircularBuffer(2048) + new RedirectThread( + errorStream, + stderrBuffer, + "Thread-ScriptTransformation-STDERR-Consumer").start() + + val outputProjection = new InterpretedProjection(input, child.output) + (proc, inputStream, outputStream, stderrBuffer, outputProjection) + } + + def execute(sqlContext: SQLContext, + child: SparkPlan, + schema: StructType): RDD[InternalRow] = { + val broadcastedHadoopConf = + new SerializableConfiguration(sqlContext.sessionState.newHadoopConf()) + + child.execute().mapPartitions { iter => + if (iter.hasNext) { + val proj = UnsafeProjection.create(schema) + processIterator(iter, broadcastedHadoopConf.value).map(proj) + } else { + // If the input iterator has no rows then do not launch the external script. + Iterator.empty + } + } + } + + def checkFailureAndPropagate(writerException: Option[Throwable], + cause: Throwable = null, + proc: Process, + stderrBuffer: CircularBuffer): Unit = { + if (writerException.isDefined) { + throw writerException.get + } + + // Checks if the proc is still alive (incase the command ran was bad) + // The ideal way to do this is to use Java 8's Process#isAlive() + // but it cannot be used because Spark still supports Java 7. + // Following is a workaround used to check if a process is alive in Java 7 + // TODO: Once builds are switched to Java 8, this can be changed + try { + val exitCode = proc.exitValue() + if (exitCode != 0) { + logError(stderrBuffer.toString) // log the stderr circular buffer + throw new SparkException(s"Subprocess exited with status $exitCode. " + + s"Error: ${stderrBuffer.toString}", cause) + } + } catch { + case _: IllegalThreadStateException => + // This means that the process is still alive. Move ahead + } + } + + def createReader(inputStream: InputStream): BufferedReader = + new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8)) + + def processIterator( + inputIterator: Iterator[InternalRow], + hadoopConf: Configuration) : Iterator[InternalRow] +} + +private[sql] class ScriptTransformationWriterThread( + iter: Iterator[InternalRow], + inputSchema: Seq[DataType], + outputProjection: Projection, + ioschema: ScriptTransformIOSchema, + outputStream: OutputStream, + proc: Process, + stderrBuffer: CircularBuffer, + taskContext: TaskContext, + conf: Configuration + ) extends Thread("Thread-ScriptTransformation-Feed") with Logging with Serializable { + + setDaemon(true) + + @volatile protected var _exception: Throwable = null + + /** Contains the exception thrown while writing the parent iterator to the external process. */ + def exception: Option[Throwable] = Option(_exception) + + protected def init(): Unit = { + TaskContext.setTaskContext(taskContext) + } + + protected def processRow(row: InternalRow, numColumns: Int): Unit = { + val data = if (numColumns == 0) { + ioschema.inputRowFormatMap("TOK_TABLEROWFORMATLINES") --- End diff -- did this change
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