hadoop VirtualInputFormat 源码
haddop VirtualInputFormat 代码
文件路径：/hadoop-tools/hadoop-dynamometer/hadoop-dynamometer-workload/src/main/java/org/apache/hadoop/tools/dynamometer/workloadgenerator/VirtualInputFormat.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.tools.dynamometer.workloadgenerator;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
/**
* An input format which does not read any input, but rather starts a
* configurable number of mappers and runs them for a configurable duration.
*/
public class VirtualInputFormat<K, V> extends FileInputFormat<K, V> {
// Number of splits = Number of mappers. Creates fakeSplits to launch
// the required number of mappers
@Override
public List<InputSplit> getSplits(JobContext job) throws IOException {
Configuration conf = job.getConfiguration();
int numMappers = conf.getInt(CreateFileMapper.NUM_MAPPERS_KEY, -1);
if (numMappers == -1) {
throw new IOException("Number of mappers should be provided as input");
}
List<InputSplit> splits = new ArrayList<InputSplit>(numMappers);
for (int i = 0; i < numMappers; i++) {
splits.add(new VirtualInputSplit());
}
return splits;
}
@Override
public RecordReader<K, V> createRecordReader(InputSplit split,
TaskAttemptContext context) throws IOException, InterruptedException {
return new VirtualRecordReader<>();
}
}
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