Spark系列(八)Worker工作原理

工作原理图

源代码分析

包名：org.apache.spark.deploy.worker

启动driver入口点：registerWithMaster方法中的case LaunchDriver

1	) => DriverState.FINISHED
37	case _ => DriverState.FAILED
38	}
39	}
40
41	finalState = Some(state)
42	// 向Driver所属worker发送DriverStateChanged消息
43	worker ! DriverStateChanged(driverId, state, finalException)
44	}
45	}.start()
46	}

LaunchExecutor

管理LaunchExecutor的启动

1	case LaunchExecutor(masterUrl, appId, execId, appDesc, cores_, memory_) =>
2	if (masterUrl != activeMasterUrl) {
3	logWarning("Invalid Master (" + masterUrl + ") attempted to launch executor.")
4	} else {
5	try {
6	logInfo("Asked to launch executor %s/%d for %s".format(appId, execId, appDesc.name))
7
8	// Create the executor's working directory
9	// 创建executor本地工作目录
10	val executorDir = new File(workDir, appId + "/" + execId)
11	if (!executorDir.mkdirs()) {
12	throw new IOException("Failed to create directory " + executorDir)
13	}
14
15	// Create local dirs for the executor. These are passed to the executor via the
16	// SPARK_LOCAL_DIRS environment variable, and deleted by the Worker when the
17	// application finishes.
18	val appLocalDirs = appDirectories.get(appId).getOrElse {
19	Utils.getOrCreateLocalRootDirs(conf).map { dir =>
20	Utils.createDirectory(dir).getAbsolutePath()
21	}.toSeq
22	}
23	appDirectories(appId) = appLocalDirs
24	// 创建ExecutorRunner对象
25	val manager = new ExecutorRunner(
26	appId,
27	execId,
28	appDesc.copy(command = Worker.maybeUpdateSSLSettings(appDesc.command, conf)),
29	cores_,
30	memory_,
31	self,
32	workerId,
33	host,
34	webUi.boundPort,
35	publicAddress,
36	sparkHome,
37	executorDir,
38	akkaUrl,
39	conf,
40	appLocalDirs, ExecutorState.LOADING)
41	// executor加入本地缓存
42	executors(appId + "/" + execId) = manager
43	manager.start()
44	// 增加worker已使用core
45	coresUsed += cores_
46	// 增加worker已使用memory
47	memoryUsed += memory_
48	// 通知master发送ExecutorStateChanged消息
49	master ! ExecutorStateChanged(appId, execId, manager.state, None, None)
50	}
51	// 异常情况处理，通知master发送ExecutorStateChanged FAILED消息
52	catch {
53	case e: Exception => {
54	logError(s"Failed to launch executor $appId/$execId for ${appDesc.name}.", e)
55	if (executors.contains(appId + "/" + execId)) {
56	executors(appId + "/" + execId).kill()
57	executors -= appId + "/" + execId
58	}
59	master ! ExecutorStateChanged(appId, execId, ExecutorState.FAILED,
60	Some(e.toString), None)
61	}
62	}
63	}

总结

1、Worker、Driver、Application启动后都会向Master进行注册,并缓存到Master内存数据模型中
2、完成注册后发送LaunchExecutor、LaunchDriver到Worker
3、Worker收到消息后启动executor和driver进程，并调用Worker的ExecutorStateChanged和DriverStateChanged方法
4、发送ExecutorStateChanged和DriverStateChanged消息到Master的，根据各自的状态信息进行处理，最重要的是会调用schedule方法进行资源的重新调度

巴特西

Spark系列(八)Worker工作原理

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