org.apache.hadoop.mapreduce.TaskAttemptID#getTaskID ( )源码实例Demo

/**
 * Given the reduce taskAttemptID, returns the TaskAttemptInfo. Deconstructs
 * the reduce taskAttemptID and looks up the jobStory with the parts taskType,
 * id of task, id of task attempt.
 * 
 * @param taskTracker
 *          tasktracker
 * @param taskAttemptID
 *          task-attempt
 * @return TaskAttemptInfo for the reduce task-attempt
 */
private TaskAttemptInfo getReduceTaskAttemptInfo(TaskTracker taskTracker,
    TaskAttemptID taskAttemptID) {
  assert (!taskAttemptID.isMap());
  TaskID taskId = taskAttemptID.getTaskID();
  TaskType taskType;
  if (taskAttemptID.isMap()) {
    taskType = TaskType.MAP;
  } else {
    taskType = TaskType.REDUCE;
  }

  TaskAttemptInfo taskAttemptInfo = jobStory.getTaskAttemptInfo(taskType,
      taskId.getId(), taskAttemptID.getId());
  if (LOG.isDebugEnabled()) {
    LOG.debug("get an attempt: "
        + taskAttemptID.toString()
        + ", state="
        + taskAttemptInfo.getRunState()
        + ", runtime="
        + ((taskAttemptID.isMap()) ? taskAttemptInfo.getRuntime()
            : ((ReduceTaskAttemptInfo) taskAttemptInfo).getReduceRuntime()));
  }
  return taskAttemptInfo;
}
 

@Override
public void cleanUpPartialOutputForTask(TaskAttemptContext context)
    throws IOException {

  // we double check this is never invoked from a non-preemptable subclass.
  // This should never happen, since the invoking codes is checking it too,
  // but it is safer to double check. Errors handling this would produce
  // inconsistent output.

  if (!this.getClass().isAnnotationPresent(Checkpointable.class)) {
    throw new IllegalStateException("Invoking cleanUpPartialOutputForTask() " +
        "from non @Preemptable class");
  }
  FileSystem fs =
    fsFor(getTaskAttemptPath(context), context.getConfiguration());

  LOG.info("cleanUpPartialOutputForTask: removing everything belonging to " +
      context.getTaskAttemptID().getTaskID() + " in: " +
      getCommittedTaskPath(context).getParent());

  final TaskAttemptID taid = context.getTaskAttemptID();
  final TaskID tid = taid.getTaskID();
  Path pCommit = getCommittedTaskPath(context).getParent();
  // remove any committed output
  for (int i = 0; i < taid.getId(); ++i) {
    TaskAttemptID oldId = new TaskAttemptID(tid, i);
    Path pTask = new Path(pCommit, oldId.toString());
    if (fs.exists(pTask) && !fs.delete(pTask, true)) {
      throw new IOException("Failed to delete " + pTask);
    }
  }
}
 

/**
 * Mask the job ID part in a {@link TaskAttemptID}.
 * 
 * @param attemptId
 *          raw {@link TaskAttemptID} read from trace
 * @return masked {@link TaskAttemptID} with empty {@link JobID}.
 */
private TaskAttemptID maskAttemptID(TaskAttemptID attemptId) {
  JobID jobId = new JobID();
  TaskType taskType = attemptId.getTaskType();
  TaskID taskId = attemptId.getTaskID();
  return new TaskAttemptID(jobId.getJtIdentifier(), jobId.getId(), taskType,
      taskId.getId(), attemptId.getId());
}
 

@Override
public void cleanUpPartialOutputForTask(TaskAttemptContext context)
    throws IOException {

  // we double check this is never invoked from a non-preemptable subclass.
  // This should never happen, since the invoking codes is checking it too,
  // but it is safer to double check. Errors handling this would produce
  // inconsistent output.

  if (!this.getClass().isAnnotationPresent(Checkpointable.class)) {
    throw new IllegalStateException("Invoking cleanUpPartialOutputForTask() " +
        "from non @Preemptable class");
  }
  FileSystem fs =
    fsFor(getTaskAttemptPath(context), context.getConfiguration());

  LOG.info("cleanUpPartialOutputForTask: removing everything belonging to " +
      context.getTaskAttemptID().getTaskID() + " in: " +
      getCommittedTaskPath(context).getParent());

  final TaskAttemptID taid = context.getTaskAttemptID();
  final TaskID tid = taid.getTaskID();
  Path pCommit = getCommittedTaskPath(context).getParent();
  // remove any committed output
  for (int i = 0; i < taid.getId(); ++i) {
    TaskAttemptID oldId = new TaskAttemptID(tid, i);
    Path pTask = new Path(pCommit, oldId.toString());
    if (fs.exists(pTask) && !fs.delete(pTask, true)) {
      throw new IOException("Failed to delete " + pTask);
    }
  }
}
 

/**
 * Mask the job ID part in a {@link TaskAttemptID}.
 * 
 * @param attemptId
 *          raw {@link TaskAttemptID} read from trace
 * @return masked {@link TaskAttemptID} with empty {@link JobID}.
 */
private TaskAttemptID maskAttemptID(TaskAttemptID attemptId) {
  JobID jobId = new JobID();
  TaskType taskType = attemptId.getTaskType();
  TaskID taskId = attemptId.getTaskID();
  return new TaskAttemptID(jobId.getJtIdentifier(), jobId.getId(), taskType,
      taskId.getId(), attemptId.getId());
}
 

@Override
public void merge(List<InMemoryMapOutput<K,V>> inputs) throws IOException {
  if (inputs == null || inputs.size() == 0) {
    return;
  }
  
  //name this output file same as the name of the first file that is 
  //there in the current list of inmem files (this is guaranteed to
  //be absent on the disk currently. So we don't overwrite a prev. 
  //created spill). Also we need to create the output file now since
  //it is not guaranteed that this file will be present after merge
  //is called (we delete empty files as soon as we see them
  //in the merge method)

  //figure out the mapId 
  TaskAttemptID mapId = inputs.get(0).getMapId();
  TaskID mapTaskId = mapId.getTaskID();

  List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
  long mergeOutputSize = 
    createInMemorySegments(inputs, inMemorySegments,0);
  int noInMemorySegments = inMemorySegments.size();

  Path outputPath = 
    mapOutputFile.getInputFileForWrite(mapTaskId,
                                       mergeOutputSize).suffix(
                                           Task.MERGED_OUTPUT_PREFIX);

  FSDataOutputStream out = CryptoUtils.wrapIfNecessary(jobConf, rfs.create(outputPath));
  Writer<K, V> writer = new Writer<K, V>(jobConf, out,
      (Class<K>) jobConf.getMapOutputKeyClass(),
      (Class<V>) jobConf.getMapOutputValueClass(), codec, null, true);

  RawKeyValueIterator rIter = null;
  CompressAwarePath compressAwarePath;
  try {
    LOG.info("Initiating in-memory merge with " + noInMemorySegments + 
             " segments...");
    
    rIter = Merger.merge(jobConf, rfs,
                         (Class<K>)jobConf.getMapOutputKeyClass(),
                         (Class<V>)jobConf.getMapOutputValueClass(),
                         inMemorySegments, inMemorySegments.size(),
                         new Path(reduceId.toString()),
                         (RawComparator<K>)jobConf.getOutputKeyComparator(),
                         reporter, spilledRecordsCounter, null, null);
    
    if (null == combinerClass) {
      Merger.writeFile(rIter, writer, reporter, jobConf);
    } else {
      combineCollector.setWriter(writer);
      combineAndSpill(rIter, reduceCombineInputCounter);
    }
    writer.close();
    compressAwarePath = new CompressAwarePath(outputPath,
        writer.getRawLength(), writer.getCompressedLength());

    LOG.info(reduceId +  
        " Merge of the " + noInMemorySegments +
        " files in-memory complete." +
        " Local file is " + outputPath + " of size " + 
        localFS.getFileStatus(outputPath).getLen());
  } catch (IOException e) { 
    //make sure that we delete the ondisk file that we created 
    //earlier when we invoked cloneFileAttributes
    localFS.delete(outputPath, true);
    throw e;
  }

  // Note the output of the merge
  closeOnDiskFile(compressAwarePath);
}
 

@Override
public void merge(List<InMemoryMapOutput<K,V>> inputs) throws IOException {
  if (inputs == null || inputs.size() == 0) {
    return;
  }
  
  //name this output file same as the name of the first file that is 
  //there in the current list of inmem files (this is guaranteed to
  //be absent on the disk currently. So we don't overwrite a prev. 
  //created spill). Also we need to create the output file now since
  //it is not guaranteed that this file will be present after merge
  //is called (we delete empty files as soon as we see them
  //in the merge method)

  //figure out the mapId 
  TaskAttemptID mapId = inputs.get(0).getMapId();
  TaskID mapTaskId = mapId.getTaskID();

  List<Segment<K, V>> inMemorySegments = new ArrayList<Segment<K, V>>();
  long mergeOutputSize = 
    createInMemorySegments(inputs, inMemorySegments,0);
  int noInMemorySegments = inMemorySegments.size();

  Path outputPath = 
    mapOutputFile.getInputFileForWrite(mapTaskId,
                                       mergeOutputSize).suffix(
                                           Task.MERGED_OUTPUT_PREFIX);

  FSDataOutputStream out = CryptoUtils.wrapIfNecessary(jobConf, rfs.create(outputPath));
  Writer<K, V> writer = new Writer<K, V>(jobConf, out,
      (Class<K>) jobConf.getMapOutputKeyClass(),
      (Class<V>) jobConf.getMapOutputValueClass(), codec, null, true);

  RawKeyValueIterator rIter = null;
  CompressAwarePath compressAwarePath;
  try {
    LOG.info("Initiating in-memory merge with " + noInMemorySegments + 
             " segments...");
    
    rIter = Merger.merge(jobConf, rfs,
                         (Class<K>)jobConf.getMapOutputKeyClass(),
                         (Class<V>)jobConf.getMapOutputValueClass(),
                         inMemorySegments, inMemorySegments.size(),
                         new Path(reduceId.toString()),
                         (RawComparator<K>)jobConf.getOutputKeyComparator(),
                         reporter, spilledRecordsCounter, null, null);
    
    if (null == combinerClass) {
      Merger.writeFile(rIter, writer, reporter, jobConf);
    } else {
      combineCollector.setWriter(writer);
      combineAndSpill(rIter, reduceCombineInputCounter);
    }
    writer.close();
    compressAwarePath = new CompressAwarePath(outputPath,
        writer.getRawLength(), writer.getCompressedLength());

    LOG.info(reduceId +  
        " Merge of the " + noInMemorySegments +
        " files in-memory complete." +
        " Local file is " + outputPath + " of size " + 
        localFS.getFileStatus(outputPath).getLen());
  } catch (IOException e) { 
    //make sure that we delete the ondisk file that we created 
    //earlier when we invoked cloneFileAttributes
    localFS.delete(outputPath, true);
    throw e;
  }

  // Note the output of the merge
  closeOnDiskFile(compressAwarePath);
}
 

/**
 * Mask the job ID part in a {@link TaskAttemptID}.
 * 
 * @param attemptId
 *          raw {@link TaskAttemptID} read from trace
 * @return masked {@link TaskAttemptID} with empty {@link JobID}.
 */
private TaskAttemptID maskAttemptID(TaskAttemptID attemptId) {
  JobID jobId = new JobID();
  TaskID taskId = attemptId.getTaskID();
  return new TaskAttemptID(jobId.getJtIdentifier(), jobId.getId(),
      attemptId.isMap(), taskId.getId(), attemptId.getId());
}