RMAppNewlySavingTransition(详见2)

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RMAppNewlySavingTransition(基于hadoop 2.7.6)

经过RMAppNewlySavingTransition后,RMApp的状态由NEW转为NEW_SAVING.根据提交上下文创建应用程序状态数据结构(主要是提交时间,启动事件,提交上下文,提交用户等),然后触发RMStateStoreEventType.STORE_APP事件,STORE_APP事件处理器会把应用程序数据结构存储到ZK上,详见3.

这个Transition比较简单,直接上代码清单

private static final class RMAppNewlySavingTransition extends RMAppTransition {
    @Override
    public void transition(RMAppImpl app, RMAppEvent event) {
      LOG.info("Storing application with id " + app.applicationId);
     app.rmContext.getStateStore().storeNewApplication(app);
    }
  }

鉴于详见1对rmContext的说明,stateStore是从ResourceManager上下文从提取的,可以猜到stateStore是ResourceManager初始化的时候创建的。见RMActiveServices的serviceInit:

protected void serviceInit(Configuration configuration) throws Exception {
	  ...省略...
RMStateStore rmStore = null;
/**
       * <!--启用自动恢复的yarn-site.xml配置-->
       *     <property>
       *         <name>yarn.resourcemanager.recovery.enabled</name>
       *         <value>true</value>
       *     </property>
       */
boolean isRecoveryEnabled = conf.getBoolean(
          YarnConfiguration.RECOVERY_ENABLED,
          YarnConfiguration.DEFAULT_RM_RECOVERY_ENABLED);
/**
   如果不是开启了恢复功能,默认是NullRMStateStore(什么都不存储)
*/
      if (isRecoveryEnabled) {
        recoveryEnabled = true;
        /**
         * <!--指定resourcemanager的状态信息存储在zookeeper集群 yarn-site.xml-->
         *   <property>
         *      <name>yarn.resourcemanager.store.class</name>
* <value>
* org.apache.hadoop.yarn.server.resourcemanager.recovery.ZKRMStateStore
* </value>
         *   </property>
         */
        rmStore = RMStateStoreFactory.getStore(conf);
        boolean isWorkPreservingRecoveryEnabled =
            conf.getBoolean(
YarnConfiguration.RM_WORK_PRESERVING_RECOVERY_ENABLED,
YarnConfiguration.DEFAULT_RM_WORK_PRESERVING_RECOVERY_ENABLED);
        rmContext.setWorkPreservingRecoveryEnabled(isWorkPreservingRecoveryEnabled);
      } else {
        recoveryEnabled = false;
        rmStore = new NullRMStateStore();
      }

      try {
        rmStore.init(conf);
        rmStore.setRMDispatcher(rmDispatcher);
        rmStore.setResourceManager(rm);
      } catch (Exception e) {
        LOG.error("Failed to init state store", e);
        throw e;
      }
      rmContext.setStateStore(rmStore);
      ...省略...
}

默认情况下是NullRMStateStore,就是什么都不做,其基类是RMStateStore，storeNewApplication方法正是基类RMStateStore的方法.

@SuppressWarnings("unchecked")
  public void storeNewApplication(RMApp app) {
    ApplicationSubmissionContext context = app
                                            .getApplicationSubmissionContext();
    assert context instanceof ApplicationSubmissionContextPBImpl;
    ApplicationStateData appState =
        ApplicationStateData.newInstance(
            app.getSubmitTime(), app.getStartTime(), context, app.getUser());
    /**
     * 注意，这里dispatcher是RMStateStore内部的调度器，由其自己的serviceInit方法中创建(非ResourceManager的全局调度器),然后把该事件放在了自己的内部事件队列中.而其中的rmDispatcher才是ResourceManager传递过来的全局调度器.RMStateStoreAppEvent的默认类型是RMStateStoreEventType.STORE_APP
     */
    dispatcher.getEventHandler().handle(new RMStateStoreAppEvent(appState));
  }

注意,这里的dispatcher是RMStateStore内部的调度器,由其自己的serviceInit方法创建(非ResourceManager的全局调度器),然后把该事件放在了自己的内部事件队列中.而其中的rmDispatcher才是ResourceManager传递过来的全局调度器.

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