【原创】大数据基础之Oozie（1）简介、源代码解析

Oozie4.3

一 简介

1 官网

http://oozie.apache.org/

Apache Oozie Workflow Scheduler for Hadoop

Hadoop生态的工作流调度器

Overview

Oozie is a workflow scheduler system to manage Apache Hadoop jobs.

Oozie Workflow jobs are Directed Acyclical Graphs (DAGs) of actions.

Oozie Coordinator jobs are recurrent Oozie Workflow jobs triggered by time (frequency) and data availability.

Oozie is integrated with the rest of the Hadoop stack supporting several types of Hadoop jobs out of the box (such as Java map-reduce, Streaming map-reduce, Pig, Hive, Sqoop and Distcp) as well as system specific jobs (such as Java programs and shell scripts).

Oozie is a scalable, reliable and extensible system.

2 部署

3 数据库表结构

wf_jobs：工作流实例

wf_actions：任务实例

coord_jobs：调度实例

coord_actions：调度任务实例

4 概念

l  Control Node：工作流的开始、结束以及决定Workflow的执行路径的节点（start、end、kill、decision、fork/join）

l  Action Node：工作流执行的计算任务，支持的类型包括（HDFS、MapReduce、Java、Shell、SSH、Pig、Hive、E-Mail、Sub-Workflow、Sqoop、Distcp），即任务

l  Workflow：由Control Node以及一系列Action Node组成的工作流，即工作流

l  Coordinator：根据指定Cron信息触发workflow，即调度

l  Bundle：按照组的方式批量管理Coordinator任务，实现集中的启停

二 代码解析

1 启动过程

加载配置的所有service：

ServicesLoader.contextInitialized

         Services.init

                  Services.loadServices (oozie.services, oozie.services.ext)

Service结构：

Service

         org.apache.oozie.service.SchedulerService,

         org.apache.oozie.service.InstrumentationService,

         org.apache.oozie.service.MemoryLocksService,

         org.apache.oozie.service.UUIDService,

         org.apache.oozie.service.ELService,

         org.apache.oozie.service.AuthorizationService,

         org.apache.oozie.service.UserGroupInformationService,

         org.apache.oozie.service.HadoopAccessorService,

         org.apache.oozie.service.JobsConcurrencyService,

         org.apache.oozie.service.URIHandlerService,

         org.apache.oozie.service.DagXLogInfoService,

         org.apache.oozie.service.SchemaService,

         org.apache.oozie.service.LiteWorkflowAppService,

         org.apache.oozie.service.JPAService,

         org.apache.oozie.service.StoreService,

         org.apache.oozie.service.SLAStoreService,

         org.apache.oozie.service.DBLiteWorkflowStoreService,

         org.apache.oozie.service.CallbackService,

         org.apache.oozie.service.ActionService,

         org.apache.oozie.service.ShareLibService,

         org.apache.oozie.service.CallableQueueService,

         org.apache.oozie.service.ActionCheckerService,

         org.apache.oozie.service.RecoveryService,

         org.apache.oozie.service.PurgeService,

         org.apache.oozie.service.CoordinatorEngineService,

         org.apache.oozie.service.BundleEngineService,

         org.apache.oozie.service.DagEngineService,

         org.apache.oozie.service.CoordMaterializeTriggerService,

         org.apache.oozie.service.StatusTransitService,

         org.apache.oozie.service.PauseTransitService,

         org.apache.oozie.service.GroupsService,

         org.apache.oozie.service.ProxyUserService,

         org.apache.oozie.service.XLogStreamingService,

         org.apache.oozie.service.JvmPauseMonitorService,

         org.apache.oozie.service.SparkConfigurationService

2 核心引擎

BaseEngine

         DAGEngine （负责workflow执行）

         CoordinatorEngine （负责coordinator执行）

         BundleEngine （负责bundle执行）

3 workflow提交执行过程

DAGEngine.submitJob| submitJobFromCoordinator （提交workflow）

         SubmitXCommand.call

                  execute

                          LiteWorkflowAppService.parseDef （解析得到WorkflowApp）

                                   LiteWorkflowLib.parseDef

                                            LiteWorkflowAppParser.validateAndParse

                                                     parse

                          WorkflowLib.createInstance （创建WorkflowInstance）

                          BatchQueryExecutor.executeBatchInsertUpdateDelete （保存WorkflowJobBean 到wf_jobs）

         StartXCommand.call

                  SignalXCommand.call

                          execute

                                   WorkflowInstance.start

                                            LiteWorkflowInstance.start

                                                     signal

                                                             NodeHandler.enter

                                                                      ActionNodeHandler.enter

                                                                               start

                                                                                        LiteWorkflowStoreService.liteExecute (添加WorkflowActionBean到ACTIONS_TO_START)

                                   WorkflowStoreService.getActionsToStart （从ACTIONS_TO_START取Action）

                                            ActionStartXCommand.call

                                                     ActionExecutor.start

                                                     WorkflowNotificationXCommand.call

                                            BatchQueryExecutor.executeBatchInsertUpdateDelete （保存WorkflowActionBean到wf_actions）

ActionExecutor.start是异步的，还需要检查Action执行状态来推进流程，有两种情况：

一种是Oozie Server正常运行：利用JobEndNotification

CallbackServlet.doGet

         DagEngine.processCallback

                  CompletedActionXCommand.call

                          ActionCheckXCommand.call

                                   ActionExecutor.check

ActionEndXCommand.call

                                            SignalXCommand.call

一种是Oozie Server重启：利用ActionCheckerService

ActionCheckerService.init

         ActionCheckRunnable.run

                  runWFActionCheck (GET_RUNNING_ACTIONS, oozie.service.ActionCheckerService.action.check.delay=600)

                          ActionCheckXCommand.call

                                    ActionExecutor.check

                                   ActionEndXCommand.call

                                            SignalXCommand.call

                  runCoordActionCheck

4 coordinator提交执行过程

CoordinatorEngine.submitJob（提交coordinator）

         CoordSubmitXCommand.call

                  submit

                          submitJob

                                   storeToDB

                                            CoordJobQueryExecutor.insert (保存CoordinatorJobBean到coord_jobs)

                                   queueMaterializeTransitionXCommand

                                            CoordMaterializeTransitionXCommand.call

                                                     execute

                                                              materialize

                                                                      materializeActions

                                                                               CoordCommandUtils.materializeOneInstance（创建CoordinatorActionBean）

                                                                                storeToDB

                                                             performWrites

                                                                      BatchQueryExecutor.executeBatchInsertUpdateDelete（保存CoordinatorActionBean到coord_actions）

                                                                      CoordActionInputCheckXCommand.call

                                                                               CoordActionReadyXCommand.call

                                                                                        CoordActionStartXCommand.call

                                                                                                DAGEngine.submitJobFromCoordinator

定时任务触发Materialize：

CoordMaterializeTriggerService.init

         CoordMaterializeTriggerRunnable.run

                  CoordMaterializeTriggerService.runCoordJobMatLookup

                          materializeCoordJobs (GET_COORD_JOBS_OLDER_FOR_MATERIALIZATION)

                                   CoordMaterializeTransitionXCommand.call

5 分布式

有些内部任务只能启动一个，单server环境Oozie中通过MemoryLocksService来保证，多server环境Oozie通过ZKLocksService来保证，要开启ZK，需要开启一些service：

org.apache.oozie.service.ZKLocksService,

org.apache.oozie.service.ZKXLogStreamingService,

org.apache.oozie.service.ZKJobsConcurrencyService,

org.apache.oozie.service.ZKUUIDService

同时需要配置oozie.zookeeper.connection.string

6 任务执行过程

ActionExecutor是任务执行的核心抽象基类，所有的具体任务都是这个类的子类

ActionExecutor

         JavaActionExecutor

         SshActionExecutor

         FsActionExecutor

         SubWorkflowActionExecutor

其中JavaActionExecutor是最重要的一个子类，很多其他的任务都是这个类的子类（比如HiveActionExecutor、SparkActionExecutor等）

JavaActionExecutor.start

         prepareActionDir

         submitLauncher

                  JobClient.getJob

                  injectLauncherCallback

                          ActionExecutor.Context.getCallbackUrl

                                   job.end.notification.url

                  createLauncherConf

                          LauncherMapperHelper.setupLauncherInfo

                  JobClient.submitJob

         check

JavaActionExecutor执行时会提交一个map任务到yarn，即LauncherMapper，

LauncherMapper.map

         LauncherMain.main

LauncherMain是具体任务的执行类

LauncherMain

         JavaMain

         HiveMain

         Hive2Main

         SparkMain

         ShellMain

         SqoopMain