背景
之前我们知道了Flink 是如何生成 StreamGraph 以及 如何生成 job 和 如何生成Task，现在我们通过 Flink Shell 将他们串起来，这样我们就学习了从写代码开始到 Flink 运行 task 的整个过程是怎么样的。
正文
我们经常通过 Flink Shell 提交代码，如 flink run -p 2 -m yarn-cluster -ynm test -c test ./test-1.0-SNAPSHOT.jar "file" "./test.properties"&通过 flink shell 我们可以知道 org.apache.flink.client.cli.CliFrontend 为整个 Flink Job 的入口类
/**
* Submits the job based on the arguments.
*/
public static void main(final String[] args) {
EnvironmentInformation.logEnvironmentInfo(LOG, "Command Line Client", args);
// 1. find the configuration directory
final String configurationDirectory = getConfigurationDirectoryFromEnv();
// 2. load the global configuration
final Configuration configuration = GlobalConfiguration.loadConfiguration(configurationDirectory);
// 3. load the custom command lines
final List> customCommandLines = loadCustomCommandLines(
configuration,
configurationDirectory);
try {
final CliFrontend cli = new CliFrontend(
configuration,
customCommandLines);
SecurityUtils.install(new SecurityConfiguration(cli.configuration));
int retCode = SecurityUtils.getInstalledContext()
.runSecured(() -> cli.parseParameters(args));
System.exit(retCode);
}
catch (Throwable t) {
final Throwable strippedThrowable = ExceptionUtils.stripException(t, UndeclaredThrowableException.class);
LOG.error("Fatal error while running command line interface.", strippedThrowable);
strippedThrowable.printStackTrace();
System.exit(31);
}
}
main 很简单，主要就两步，发现并加载配置文件，加载并解析命令。在解析命令的过程当中，如果传入的命令是 run，则可以一直追踪到 executeProgram 方法
protected void executeProgram(PackagedProgram program, ClusterClient client, int parallelism) throws ProgramMissingJobException, ProgramInvocationException {
logAndSysout("Starting execution of program");
final JobSubmissionResult result = client.run(program, parallelism);
......
}
通过 client run 方法来执行，最终调用我们传入的主方法( 通过 -c 参数)，然后就开始执行用户代码了，首先会构建 StreamGraph ，最终调用 StreamContextEnvironment execute(String jobName) 方法
@Override
public JobExecutionResult execute(String jobName) throws Exception {
Preconditions.checkNotNull(jobName, "Streaming Job name should not be null.");
StreamGraph streamGraph = this.getStreamGraph();
streamGraph.setJobName(jobName);
transformations.clear();
// execute the programs 存在 -d 时
if (ctx instanceof DetachedEnvironment) {
LOG.warn("Job was executed in detached mode, the results will be available on completion.");
((DetachedEnvironment) ctx).setDetachedPlan(streamGraph);
return DetachedEnvironment.DetachedJobExecutionResult.INSTANCE;
} else {
return ctx
.getClient()
.run(streamGraph, ctx.getJars(), ctx.getClasspaths(), ctx.getUserCodeClassLoader(), ctx.getSavepointRestoreSettings())
.getJobExecutionResult();
}
}
然后
public JobSubmissionResult run(FlinkPlan compiledPlan,
List libraries, List classpaths, ClassLoader classLoader, SavepointRestoreSettings savepointSettings)
throws ProgramInvocationException {
// 构建 jobGraph
JobGraph job = getJobGraph(flinkConfig, compiledPlan, libraries, classpaths, savepointSettings);
//将 job 提交至 cluster 上
return submitJob(job, classLoader);
}
主要就是构建 jobGraph ，关于构建 jobGraph 的细节可以参考 如何构建 job ，构建成功之后就开始提交 job 了。我们以 MiniCluster 为例
@Override
public JobSubmissionResult submitJob(JobGraph jobGraph, ClassLoader classLoader) throws ProgramInvocationException {
final CompletableFuture jobSubmissionResultFuture = submitJob(jobGraph);
......
}
public CompletableFuture submitJob(JobGraph jobGraph) {
final CompletableFuture dispatcherGatewayFuture = getDispatcherGatewayFuture();
// we have to allow queued scheduling in Flip-6 mode because we need to request slots
// from the ResourceManager
jobGraph.setAllowQueuedScheduling(true);
final CompletableFuture blobServerAddressFuture = createBlobServerAddress(dispatcherGatewayFuture);
// cache jars and files
final CompletableFuture jarUploadFuture = uploadAndSetJobFiles(blobServerAddressFuture, jobGraph);
final CompletableFuture acknowledgeCompletableFuture = jarUploadFuture
.thenCombine(
dispatcherGatewayFuture,
// 这里真正 submit 操作,交给了 dispatcher 去执行
(Void ack, DispatcherGateway dispatcherGateway) -> dispatcherGateway.submitJob(jobGraph, rpcTimeout))
.thenCompose(Function.identity());
return acknowledgeCompletableFuture.thenApply(
(Acknowledge ignored) -> new JobSubmissionResult(jobGraph.getJobID()));
}
接下来就到了 job 正式运行的时候了
private CompletableFuture runJob(JobGraph jobGraph) {
Preconditions.checkState(!jobManagerRunnerFutures.containsKey(jobGraph.getJobID()));
//创建 jobManagerRunner 同时也会创建 jobMaster，在创建 JobMaster 的时候构建了 ExecutionGraph
final CompletableFuture jobManagerRunnerFuture = createJobManagerRunner(jobGraph);
jobManagerRunnerFutures.put(jobGraph.getJobID(), jobManagerRunnerFuture);
// start jobManagerRunner 同时也启动了 jobMaster 等一系列 service,然后就开始调度 executionGraph，execution.deploy task.start
return jobManagerRunnerFuture
.thenApply(FunctionUtils.uncheckedFunction(this::startJobManagerRunner))
.thenApply(FunctionUtils.nullFn())
.whenCompleteAsync(
(ignored, throwable) -> {
if (throwable != null) {
jobManagerRunnerFutures.remove(jobGraph.getJobID());
}
},
getMainThreadExecutor());
}
这部分内容与 如何构建Job 是一致的，省略若干，具体可以参考 如何构建 job ，需要强调一点就是当 执行到 ExecutionGraph 的 scheduleForExecution方法时
// 调度 execution
public void scheduleForExecution() throws JobException {
assertRunningInJobMasterMainThread();
final long currentGlobalModVersion = globalModVersion;
// 会启动 startCheckpointScheduler
if (transitionState(JobStatus.CREATED, JobStatus.RUNNING)) {
......
}
会启动 CheckpointScheduler 从而开始出发 checkpoint。
接下来就开始部署，可以参考 如何构建 job 和 如何生成Task
至此为止，从写代码到代码的计算执行，整个过程我们都已经学习清楚了。
总结
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