AM启动--AMContainerAllocatedTransition(二)

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AMContainerAllocatedTransition(基于hadoop 2.7.6)

前述RmAppAttempt的状态转换:
AttemptStartedTransition:NEW–>SUBMITTED
ScheduleTransition:SUBMITTED–>SCHEDULED

主要逻辑步骤:
     1.调用scheduler.allocate方法,触发RMContainerEventType.ACQUIRED事件(该事件的处理器AcquiredTransition会将Container加入到containerAllocationExpirer)
     2.触发RMStateStoreEventType.STORE_APP_ATTEMPT事件

AMContainerAllocatedTransition转换器处理后,RmAppAttempt的状态由SCHEDULED转换为ALLOCATED_SAVING.

/**
   *	主要逻辑:
   *		1.调用scheduler.allocate方法
   *		2.触发RMStateStoreEventType.STORE_APP_ATTEMPT事件
   */
  private static final class AMContainerAllocatedTransition
      implements
      MultipleArcTransition<RMAppAttemptImpl, RMAppAttemptEvent, RMAppAttemptState> {
    @Override
    public RMAppAttemptState transition(RMAppAttemptImpl appAttempt,
        RMAppAttemptEvent event) {
      // Acquire the AM container from the scheduler.
    	/**
    	 * 		
    	 * 		1.释放已经完成的Container.
    	 * 		2.将新需求更新到(FiCaSchedulerApp)application里的(Map<Priority, Map<String, ResourceRequest>>)requests列表
    	 * 		3.getAllocation方法
    	 * 			3.1为已分配的Container创建NMToken
    	 * 			3.2会触发RMContainerEventType.ACQUIRED事件,该事件由AcquiredTransition处理,会将container加入到containerAllocationExpirer
    	 * 			
    	 */
      Allocation amContainerAllocation =
          appAttempt.scheduler.allocate(appAttempt.applicationAttemptId,
            EMPTY_CONTAINER_REQUEST_LIST, EMPTY_CONTAINER_RELEASE_LIST, null,
            null);
      /**
       * 	存在创建NMToken失败的情况,则重新触发RMAppAttemptEventType.CONTAINER_ALLOCATED用于再次分配资源
       */
      if (amContainerAllocation.getContainers().size() == 0) {
    	  /**
    	   * 	重新触发事件:RMAppAttemptEventType.CONTAINER_ALLOCATED
    	   */
        appAttempt.retryFetchingAMContainer(appAttempt);
        return RMAppAttemptState.SCHEDULED;
      }

      /**
       * 	AM只需要一个Container
       */
      appAttempt.setMasterContainer(amContainerAllocation.getContainers()
          .get(0));
      RMContainerImpl rmMasterContainer = (RMContainerImpl)appAttempt.scheduler
          .getRMContainer(appAttempt.getMasterContainer().getId());
      /**
       * 	设置为AmContainer
       */
      rmMasterContainer.setAMContainer(true);
      appAttempt.rmContext.getNMTokenSecretManager()
  .clearNodeSetForAttempt(appAttempt.applicationAttemptId);
      appAttempt.getSubmissionContext().setResource(
        appAttempt.getMasterContainer().getResource());
      /**
       * 	触发事件:RMStateStoreAppAttemptEvent(RMStateStoreEventType.STORE_APP_ATTEMPT)
       */
      appAttempt.storeAttempt();
      return RMAppAttemptState.ALLOCATED_SAVING;
    }
  }