hadoop MergeManager 源码
haddop MergeManager 代码
文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManager.java
/**
* 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.hadoop.mapreduce.task.reduce;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.mapred.RawKeyValueIterator;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import java.io.IOException;
/**
* An interface for a reduce side merge that works with the default Shuffle
* implementation.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public interface MergeManager<K, V> {
/**
* To wait until merge has some freed resources available so that it can
* accept shuffled data. This will be called before a network connection is
* established to get the map output.
*/
public void waitForResource() throws InterruptedException;
/**
* To reserve resources for data to be shuffled. This will be called after
* a network connection is made to shuffle the data.
* @param mapId mapper from which data will be shuffled.
* @param requestedSize size in bytes of data that will be shuffled.
* @param fetcher id of the map output fetcher that will shuffle the data.
* @return a MapOutput object that can be used by shuffle to shuffle data. If
* required resources cannot be reserved immediately, a null can be returned.
*/
public MapOutput<K, V> reserve(TaskAttemptID mapId, long requestedSize,
int fetcher) throws IOException;
/**
* Called at the end of shuffle.
* @return a key value iterator object.
*/
public RawKeyValueIterator close() throws Throwable;
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
7、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦