1 | /** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one |
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3 | * or more contributor license agreements. See the NOTICE file |
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4 | * distributed with this work for additional information |
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5 | * regarding copyright ownership. The ASF licenses this file |
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6 | * to you under the Apache License, Version 2.0 (the |
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7 | * "License"); you may not use this file except in compliance |
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8 | * with the License. You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | */ |
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18 | |
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19 | package org.apache.hadoop.mapreduce.lib.map; |
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20 | |
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21 | import org.apache.hadoop.util.ReflectionUtils; |
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22 | import org.apache.hadoop.conf.Configuration; |
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23 | import org.apache.hadoop.mapreduce.Counter; |
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24 | import org.apache.hadoop.mapreduce.InputSplit; |
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25 | import org.apache.hadoop.mapreduce.Job; |
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26 | import org.apache.hadoop.mapreduce.JobContext; |
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27 | import org.apache.hadoop.mapreduce.Mapper; |
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28 | import org.apache.hadoop.mapreduce.RecordReader; |
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29 | import org.apache.hadoop.mapreduce.RecordWriter; |
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30 | import org.apache.hadoop.mapreduce.StatusReporter; |
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31 | import org.apache.hadoop.mapreduce.TaskAttemptContext; |
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32 | import org.apache.commons.logging.Log; |
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33 | import org.apache.commons.logging.LogFactory; |
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34 | |
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35 | import java.io.IOException; |
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36 | import java.util.ArrayList; |
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37 | import java.util.List; |
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38 | |
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39 | /** |
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40 | * Multithreaded implementation for @link org.apache.hadoop.mapreduce.Mapper. |
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41 | * <p> |
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42 | * It can be used instead of the default implementation, |
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43 | * @link org.apache.hadoop.mapred.MapRunner, when the Map operation is not CPU |
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44 | * bound in order to improve throughput. |
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45 | * <p> |
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46 | * Mapper implementations using this MapRunnable must be thread-safe. |
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47 | * <p> |
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48 | * The Map-Reduce job has to be configured with the mapper to use via |
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49 | * {@link #setMapperClass(Configuration, Class)} and |
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50 | * the number of thread the thread-pool can use with the |
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51 | * {@link #getNumberOfThreads(Configuration) method. The default |
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52 | * value is 10 threads. |
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53 | * <p> |
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54 | */ |
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55 | public class MultithreadedMapper<K1, V1, K2, V2> |
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56 | extends Mapper<K1, V1, K2, V2> { |
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57 | |
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58 | private static final Log LOG = LogFactory.getLog(MultithreadedMapper.class); |
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59 | private Class<? extends Mapper<K1,V1,K2,V2>> mapClass; |
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60 | private Context outer; |
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61 | private List<MapRunner> runners; |
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62 | |
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63 | /** |
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64 | * The number of threads in the thread pool that will run the map function. |
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65 | * @param job the job |
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66 | * @return the number of threads |
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67 | */ |
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68 | public static int getNumberOfThreads(JobContext job) { |
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69 | return job.getConfiguration(). |
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70 | getInt("mapred.map.multithreadedrunner.threads", 10); |
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71 | } |
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72 | |
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73 | /** |
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74 | * Set the number of threads in the pool for running maps. |
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75 | * @param job the job to modify |
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76 | * @param threads the new number of threads |
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77 | */ |
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78 | public static void setNumberOfThreads(Job job, int threads) { |
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79 | job.getConfiguration().setInt("mapred.map.multithreadedrunner.threads", |
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80 | threads); |
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81 | } |
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82 | |
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83 | /** |
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84 | * Get the application's mapper class. |
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85 | * @param <K1> the map's input key type |
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86 | * @param <V1> the map's input value type |
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87 | * @param <K2> the map's output key type |
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88 | * @param <V2> the map's output value type |
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89 | * @param job the job |
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90 | * @return the mapper class to run |
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91 | */ |
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92 | @SuppressWarnings("unchecked") |
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93 | public static <K1,V1,K2,V2> |
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94 | Class<Mapper<K1,V1,K2,V2>> getMapperClass(JobContext job) { |
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95 | return (Class<Mapper<K1,V1,K2,V2>>) |
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96 | job.getConfiguration().getClass("mapred.map.multithreadedrunner.class", |
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97 | Mapper.class); |
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98 | } |
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99 | |
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100 | /** |
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101 | * Set the application's mapper class. |
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102 | * @param <K1> the map input key type |
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103 | * @param <V1> the map input value type |
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104 | * @param <K2> the map output key type |
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105 | * @param <V2> the map output value type |
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106 | * @param job the job to modify |
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107 | * @param cls the class to use as the mapper |
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108 | */ |
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109 | public static <K1,V1,K2,V2> |
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110 | void setMapperClass(Job job, |
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111 | Class<? extends Mapper<K1,V1,K2,V2>> cls) { |
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112 | if (MultithreadedMapper.class.isAssignableFrom(cls)) { |
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113 | throw new IllegalArgumentException("Can't have recursive " + |
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114 | "MultithreadedMapper instances."); |
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115 | } |
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116 | job.getConfiguration().setClass("mapred.map.multithreadedrunner.class", |
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117 | cls, Mapper.class); |
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118 | } |
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119 | |
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120 | /** |
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121 | * Run the application's maps using a thread pool. |
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122 | */ |
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123 | @Override |
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124 | public void run(Context context) throws IOException, InterruptedException { |
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125 | outer = context; |
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126 | int numberOfThreads = getNumberOfThreads(context); |
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127 | mapClass = getMapperClass(context); |
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128 | if (LOG.isDebugEnabled()) { |
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129 | LOG.debug("Configuring multithread runner to use " + numberOfThreads + |
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130 | " threads"); |
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131 | } |
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132 | |
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133 | runners = new ArrayList<MapRunner>(numberOfThreads); |
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134 | for(int i=0; i < numberOfThreads; ++i) { |
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135 | MapRunner thread = new MapRunner(context); |
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136 | thread.start(); |
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137 | runners.add(i, thread); |
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138 | } |
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139 | for(int i=0; i < numberOfThreads; ++i) { |
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140 | MapRunner thread = runners.get(i); |
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141 | thread.join(); |
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142 | Throwable th = thread.throwable; |
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143 | if (th != null) { |
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144 | if (th instanceof IOException) { |
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145 | throw (IOException) th; |
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146 | } else if (th instanceof InterruptedException) { |
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147 | throw (InterruptedException) th; |
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148 | } else { |
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149 | throw new RuntimeException(th); |
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150 | } |
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151 | } |
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152 | } |
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153 | } |
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154 | |
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155 | private class SubMapRecordReader extends RecordReader<K1,V1> { |
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156 | private K1 key; |
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157 | private V1 value; |
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158 | private Configuration conf; |
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159 | |
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160 | @Override |
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161 | public void close() throws IOException { |
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162 | } |
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163 | |
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164 | @Override |
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165 | public float getProgress() throws IOException, InterruptedException { |
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166 | return 0; |
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167 | } |
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168 | |
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169 | @Override |
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170 | public void initialize(InputSplit split, |
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171 | TaskAttemptContext context |
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172 | ) throws IOException, InterruptedException { |
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173 | conf = context.getConfiguration(); |
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174 | } |
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175 | |
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176 | |
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177 | @Override |
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178 | public boolean nextKeyValue() throws IOException, InterruptedException { |
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179 | synchronized (outer) { |
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180 | if (!outer.nextKeyValue()) { |
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181 | return false; |
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182 | } |
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183 | key = ReflectionUtils.copy(outer.getConfiguration(), |
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184 | outer.getCurrentKey(), key); |
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185 | value = ReflectionUtils.copy(conf, outer.getCurrentValue(), value); |
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186 | return true; |
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187 | } |
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188 | } |
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189 | |
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190 | public K1 getCurrentKey() { |
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191 | return key; |
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192 | } |
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193 | |
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194 | @Override |
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195 | public V1 getCurrentValue() { |
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196 | return value; |
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197 | } |
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198 | } |
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199 | |
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200 | private class SubMapRecordWriter extends RecordWriter<K2,V2> { |
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201 | |
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202 | @Override |
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203 | public void close(TaskAttemptContext context) throws IOException, |
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204 | InterruptedException { |
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205 | } |
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206 | |
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207 | @Override |
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208 | public void write(K2 key, V2 value) throws IOException, |
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209 | InterruptedException { |
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210 | synchronized (outer) { |
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211 | outer.write(key, value); |
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212 | } |
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213 | } |
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214 | } |
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215 | |
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216 | private class SubMapStatusReporter extends StatusReporter { |
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217 | |
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218 | @Override |
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219 | public Counter getCounter(Enum<?> name) { |
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220 | return outer.getCounter(name); |
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221 | } |
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222 | |
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223 | @Override |
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224 | public Counter getCounter(String group, String name) { |
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225 | return outer.getCounter(group, name); |
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226 | } |
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227 | |
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228 | @Override |
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229 | public void progress() { |
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230 | outer.progress(); |
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231 | } |
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232 | |
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233 | @Override |
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234 | public void setStatus(String status) { |
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235 | outer.setStatus(status); |
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236 | } |
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237 | |
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238 | } |
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239 | |
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240 | private class MapRunner extends Thread { |
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241 | private Mapper<K1,V1,K2,V2> mapper; |
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242 | private Context subcontext; |
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243 | private Throwable throwable; |
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244 | |
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245 | MapRunner(Context context) throws IOException, InterruptedException { |
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246 | mapper = ReflectionUtils.newInstance(mapClass, |
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247 | context.getConfiguration()); |
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248 | subcontext = new Context(outer.getConfiguration(), |
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249 | outer.getTaskAttemptID(), |
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250 | new SubMapRecordReader(), |
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251 | new SubMapRecordWriter(), |
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252 | context.getOutputCommitter(), |
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253 | new SubMapStatusReporter(), |
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254 | outer.getInputSplit()); |
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255 | } |
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256 | |
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257 | public Throwable getThrowable() { |
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258 | return throwable; |
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259 | } |
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260 | |
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261 | @Override |
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262 | public void run() { |
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263 | try { |
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264 | mapper.run(subcontext); |
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265 | } catch (Throwable ie) { |
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266 | throwable = ie; |
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267 | } |
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268 | } |
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269 | } |
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270 | |
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271 | } |
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