读hadoop0.23源码(1)：Job

每次配置job的时候，最后一步总是

 

System.exit(job.waitForCompletion(true) ? 0 : 1);

 进入waitForCompletion方法

 

public boolean waitForCompletion(boolean verbose
                                   ) throws IOException, InterruptedException,
                                            ClassNotFoundException {
    if (state == JobState.DEFINE) {
      submit();
    }
    if (verbose) {
      jobClient.monitorAndPrintJob(conf, info);//设置参数是否打印执行过程
    } else {
      info.waitForCompletion();
    }
    return isSuccessful();
  }

 

submit()方法是根据你设置的job属性来执行job，以下是submit()方法：

 

public void submit() throws IOException, InterruptedException, 
                              ClassNotFoundException {
    ensureState(JobState.DEFINE);//确认job开始执行
    setUseNewAPI();
    
    // 连接到jobTrack并且提交job
    connect();			
    info = jobClient.submitJobInternal(conf);
    super.setJobID(info.getID());
    state = JobState.RUNNING;
   }

 

在connect()方法中实例化了jobClient，然后调用jobClient.submitJobInternal 提交job