用户编写的可执行Jar包，在本地客户端生成JobGraph，先看下flink生成并提交JobGraph的大致流程。
提交过程
- 首先，生成PackagedProgram。
- 接着，通过PackagedProgramUtils从PackagedProgram中提取JobGraph。
- 最后，通过ClusterDescriptor将JobGraph提交到集群中。
关于任务提交这部分可以参考flinkStreamSQL任务提交流程代码，比直接看源码要简单很多。此处，我参考flink1.8源码进行说明。
生成PackagedProgram
buildProgram通过提取命令行中传递的参数，将用户程序jarFile、程序参数programArgs、程序依赖的classpaths传递给PackagedProgram。entryPointClass如果不传递，可以通过程序解析出来。
CliFrontend#buildProgram
PackagedProgram buildProgram(ProgramOptions options) throws FileNotFoundException, ProgramInvocationException {
String[] programArgs = options.getProgramArgs();
String jarFilePath = options.getJarFilePath();
List classpaths = options.getClasspaths();
File jarFile = new File(jarFilePath);
// main方法类
String entryPointClass = options.getEntryPointClassName();
PackagedProgram program = entryPointClass == null ?
new PackagedProgram(jarFile, classpaths, programArgs) :
new PackagedProgram(jarFile, classpaths, entryPointClass, programArgs);
return program;
}
public PackagedProgram(File jarFile, List classpaths, @Nullable String entryPointClassName, String... args) throws ProgramInvocationException {
// 用户jar路径
URL jarFileUrl = jarFile.getAbsoluteFile().toURI().toURL();
this.jarFile = jarFileUrl;
this.args = args == null ? new String[0] : args;
// 如果没有传递entryPointClassName, 可以通过manifest提取
if (entryPointClassName == null) {
entryPointClassName = getEntryPointClassNameFromJar(jarFileUrl);
}
//抽取当前jar中包含的jar,包含/lib且名称以.jar结尾
this.extractedTempLibraries = extractContainedLibraries(jarFileUrl);
this.classpaths = classpaths;
// 使用FlinkUserCodeClassLoaders加载getAllLibraries中的jar
this.userCodeClassLoader = JobWithJars.buildUserCodeClassLoader(getAllLibraries(), classpaths, getClass().getClassLoader());
// 使用FlinkUserCodeClassLoaders加载器加载该类，然后切换回父类加载器
this.mainClass = loadMainClass(entryPointClassName, userCodeClassLoader);
// if the entry point is a program, instantiate the class and get the plan
if (Program.class.isAssignableFrom(this.mainClass)) {
Program prg = null;
try {
prg = InstantiationUtil.instantiate(this.mainClass.asSubclass(Program.class), Program.class);
} catch (Exception e) {
// validate that the class has a main method at least.
// the main method possibly instantiates the program properly
if (!hasMainMethod(mainClass)) {
throw new ProgramInvocationException("The given program class implements the " +
Program.class.getName() + " interface, but cannot be instantiated. " +
"It also declares no main(String[]) method as alternative entry point", e);
}
} catch (Throwable t) {
throw new ProgramInvocationException("Error while trying to instantiate program class.", t);
}
this.program = prg;
} else if (hasMainMethod(mainClass)) {
//用户类不为Program的子类
this.program = null;
} else {
throw new ProgramInvocationException("The given program class neither has a main(String[]) method, nor does it implement the " +
Program.class.getName() + " interface.");
}
}
提取JobGraph
通过生成的PackagedProgram、flinkconf中参数配置、任务并行度生成jobGraph，并通过clusterDescriptor进行提交。
CliFrontend#runProgram
## 部署任务到新集群
if (clusterId == null && runOptions.getDetachedMode()) {
int parallelism = runOptions.getParallelism() == -1 ? defaultParallelism : runOptions.getParallelism();
// 构建jobGraph
final JobGraph jobGraph = PackagedProgramUtils.createJobGraph(program, configuration, parallelism);
final ClusterSpecification clusterSpecification = customCommandLine.getClusterSpecification(commandLine);
//部署
client = clusterDescriptor.deployJobCluster(
clusterSpecification,
jobGraph,
runOptions.getDetachedMode());
logAndSysout("Job has been submitted with JobID " + jobGraph.getJobID());
try {
client.shutdown();
} catch (Exception e) {
LOG.info("Could not properly shut down the client.", e);
}
}
## createJobGraph
public static JobGraph createJobGraph(
PackagedProgram packagedProgram,
Configuration configuration,
int defaultParallelism,
@Nullable JobID jobID) throws ProgramInvocationException {
Thread.currentThread().setContextClassLoader(packagedProgram.getUserCodeClassLoader());
// 优化器
final Optimizer optimizer = new Optimizer(new DataStatistics(), new DefaultCostEstimator(), configuration);
final FlinkPlan flinkPlan;
final OptimizerPlanEnvironment optimizerPlanEnvironment = new OptimizerPlanEnvironment(optimizer);
optimizerPlanEnvironment.setParallelism(defaultParallelism);
// 形成StreamingPlan
flinkPlan = optimizerPlanEnvironment.getOptimizedPlan(packagedProgram);
final JobGraph jobGraph;
if (flinkPlan instanceof StreamingPlan) {
// 从StreamingPlan中提取jobGraph
jobGraph = ((StreamingPlan) flinkPlan).getJobGraph(jobID);
jobGraph.setSavepointRestoreSettings(packagedProgram.getSavepointSettings());
} else {
final JobGraphGenerator jobGraphGenerator = new JobGraphGenerator(configuration);
jobGraph = jobGraphGenerator.compileJobGraph((OptimizedPlan) flinkPlan, jobID);
}
// 用户Jar中的依赖jar包传递给jobGraph
for (URL url : packagedProgram.getAllLibraries()) {
try {
jobGraph.addJar(new Path(url.toURI()));
} catch (URISyntaxException e) {
throw new ProgramInvocationException("Invalid URL for jar file: " + url + '.', jobGraph.getJobID(), e);
}
}
// classpaths的传递有多中方式:
// 1.通过packagedProgram构造函数直接传递
// 2.先产生jobGraph，然后调用setClasspaths绑定。
// 3. ContextEnvironment.getClasspaths.add(url)传递。
jobGraph.setClasspaths(packagedProgram.getClasspaths());ContextEnvironment
return jobGraph;
}
## flinkstreamsql中classpath传递
main方法中通过env.registerCachedFile(url.getPath(), classFileName, true);将插件包的url存放到cacheFile中，当提交时取出并绑定给jobGraph。
private static void fillJobGraphClassPath(JobGraph jobGraph) throws MalformedURLException {
Map jobCacheFileConfig = jobGraph.getJobConfiguration().toMap();
Set classPathKeySet = Sets.newHashSet();
for(Map.Entry tmp : jobCacheFileConfig.entrySet()){
if(Strings.isNullOrEmpty(tmp.getValue())){
continue;
}
if(tmp.getValue().startsWith("class_path")){
//DISTRIBUTED_CACHE_FILE_NAME_1
//DISTRIBUTED_CACHE_FILE_PATH_1
String key = tmp.getKey();
String[] array = key.split("_");
if(array.length < 5){
continue;
}
array[3] = "PATH";
classPathKeySet.add(StringUtils.join(array, "_"));
}
}
for(String key : classPathKeySet){
String pathStr = jobCacheFileConfig.get(key);
jobGraph.getClasspaths().add(new URL("file:" + pathStr));
}
}
形成StreamingPlan
在提取StreamingPlan时，需要先构建OptimizerPlanEnvironment，由该Environment通过反射执行用户Main类。在Main方法中，通过执行execute形成StreamingPlan并主动抛出ProgramAbortException，被上层捕获到。
final OptimizerPlanEnvironment optimizerPlanEnvironment = new OptimizerPlanEnvironment(optimizer);
optimizerPlanEnvironment.setParallelism(defaultParallelism);
## 抽取StreamingPlan
flinkPlan = optimizerPlanEnvironment.getOptimizedPlan(packagedProgram);
public FlinkPlan getOptimizedPlan(PackagedProgram prog) throws ProgramInvocationException {
// ExecutionEnvironmentFactory创建的对象为OptimizerPlanEnvironment
setAsContext();
try {
// 在OptimizerPlanEnvironment环境下执行Main方法，形成optimizerPlan
prog.invokeInteractiveModeForExecution();
}
catch (ProgramInvocationException e) {
throw e;
}
catch (Throwable t) {
// 捕获Main方法中抛出的异常，获取StreamingPlan
if (optimizerPlan != null) {
return optimizerPlan;
} else {
throw new ProgramInvocationException("The program caused an error: ", t);
}
}
finally {
unsetAsContext();
}
}
Main方法中的execute()方法：
- 构造出streamGraph
- 填充到Environment中
- 主动抛出异常让上层捕获
@Override
public JobExecutionResult execute(String jobName) throws Exception {
//生成streamGraph
StreamGraph streamGraph = getStreamGraph();
streamGraph.setJobName(jobName);
transformations.clear();
if (env instanceof OptimizerPlanEnvironment) {
((OptimizerPlanEnvironment) env).setPlan(streamGraph);
} else if (env instanceof PreviewPlanEnvironment) {
((PreviewPlanEnvironment) env).setPreview(streamGraph.getStreamingPlanAsJSON());
}
throw new OptimizerPlanEnvironment.ProgramAbortException();
}
StreamExecutionEnvironment.getExecutionEnvironment()方法获取执行环境：
- ContextEnvironment：Execution Environment for remote execution with the Client.物理执行环境。
- LocalEnvironment：本地调试使用的执行环境。
- StreamPlanEnvironment： 主要用来生成streaming job。
由于在getOptimizedPlan中调用了setAsContext方法，ExecutionEnvironmentFactory创建OptimizerPlanEnvironment，因此返回StreamPlanEnvironment。
public static StreamExecutionEnvironment getExecutionEnvironment() {
if (contextEnvironmentFactory != null) {
return contextEnvironmentFactory.createExecutionEnvironment();
}
// because the streaming project depends on "flink-clients" (and not the other way around)
// we currently need to intercept the data set environment and create a dependent stream env.
// this should be fixed once we rework the project dependencies
ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
if (env instanceof ContextEnvironment) {
return new StreamContextEnvironment((ContextEnvironment) env);
} else if (env instanceof OptimizerPlanEnvironment || env instanceof PreviewPlanEnvironment) {
return new StreamPlanEnvironment(env);
} else {
return createLocalEnvironment();
}
}
// 根据contextEnvironmentFactory生成ExecutionEnvironment
public static ExecutionEnvironment getExecutionEnvironment() {
return (ExecutionEnvironment)(contextEnvironmentFactory == null ? createLocalEnvironment() : contextEnvironmentFactory.createExecutionEnvironment());
}
总之，根据用户启动任务的环境，构造相应的执行环境。通过反射执行用户编写的Main方法，并抽取出StreamPlan，Main在执行时使用的是外部创建出的执行环境。