org.apache.spark.ContextAwareIterator.scala Maven / Gradle / Ivy
/*
* 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,
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*/
package org.apache.spark
import org.apache.spark.annotation.DeveloperApi
/**
* :: DeveloperApi ::
* A TaskContext aware iterator.
*
* As the Python evaluation consumes the parent iterator in a separate thread,
* it could consume more data from the parent even after the task ends and the parent is closed.
* If an off-heap access exists in the parent iterator, it could cause segmentation fault
* which crashes the executor.
* Thus, we should use [[ContextAwareIterator]] to stop consuming after the task ends.
*
* @since 3.1.0
*/
@DeveloperApi
class ContextAwareIterator[+T](val context: TaskContext, val delegate: Iterator[T])
extends Iterator[T] {
override def hasNext: Boolean =
!context.isCompleted() && !context.isInterrupted() && delegate.hasNext
override def next(): T = delegate.next()
}