Flink架构
Flink不仅提供实时流计算,也支持批处理,所谓流批一体。对外提供DataStream和Table API、Flink SQL接口。
DataStream API
DataStream是Flink的核心数据结构,一般从StreamExecutionEnvironment开始构造数据流。
flink\flink-streaming-java\src\main\java\org\apache\flink\streaming\api\datastream\DataStream.java
以下是DataStream的所有方法。
通过DataStream编织完业务逻辑,Flink先将数据流编译成JobGraph,然后就可以将ApplicationMaster提交到Yarn集群计算了。
private ApplicationReport startAppMaster(
Configuration configuration,
String applicationName,
String yarnClusterEntrypoint,
JobGraph jobGraph,
YarnClient yarnClient,
YarnClientApplication yarnApplication,
ClusterSpecification clusterSpecification)
throws Exception {
// ------------------ Initialize the file systems -------------------------
org.apache.flink.core.fs.FileSystem.initialize(
configuration, PluginUtils.createPluginManagerFromRootFolder(configuration));
final FileSystem fs = FileSystem.get(yarnConfiguration);
// hard coded check for the GoogleHDFS client because its not overriding the getScheme()
// method.
if (!fs.getClass().getSimpleName().equals("GoogleHadoopFileSystem")
&& fs.getScheme().startsWith("file")) {
LOG.warn(
"The file system scheme is '"
+ fs.getScheme()
+ "'. This indicates that the "
+ "specified Hadoop configuration path is wrong and the system is using the default Hadoop configuration values."
+ "The Flink YARN client needs to store its files in a distributed file system");
}
ApplicationSubmissionContext appContext = yarnApplication.getApplicationSubmissionContext();
final List<Path> providedLibDirs =
Utils.getQualifiedRemoteSharedPaths(configuration, yarnConfiguration);
final YarnApplicationFileUploader fileUploader =
YarnApplicationFileUploader.from(
fs,
getStagingDir(fs),
providedLibDirs,
appContext.getApplicationId(),
getFileReplication());
// The files need to be shipped and added to classpath.
Set<File> systemShipFiles = new HashSet<>(shipFiles.size());
for (File file : shipFiles) {
systemShipFiles.add(file.getAbsoluteFile());
}
final String logConfigFilePath =
configuration.getString(YarnConfigOptionsInternal.APPLICATION_LOG_CONFIG_FILE);
if (logConfigFilePath != null) {
systemShipFiles.add(new File(logConfigFilePath));
}
// Set-up ApplicationSubmissionContext for the application
final ApplicationId appId = appContext.getApplicationId();
// ------------------ Add Zookeeper namespace to local flinkConfiguraton ------
setHAClusterIdIfNotSet(configuration, appId);
if (HighAvailabilityMode.isHighAvailabilityModeActivated(configuration)) {
// activate re-execution of failed applications
appContext.setMaxAppAttempts(
configuration.getInteger(
YarnConfigOptions.APPLICATION_ATTEMPTS.key(),
YarnConfiguration.DEFAULT_RM_AM_MAX_ATTEMPTS));
activateHighAvailabilitySupport(appContext);
} else {
// set number of application retries to 1 in the default case
appContext.setMaxAppAttempts(
configuration.getInteger(YarnConfigOptions.APPLICATION_ATTEMPTS.key(), 1));
}
final Set<Path> userJarFiles = new HashSet<>();
if (jobGraph != null) {
userJarFiles.addAll(
jobGraph.getUserJars().stream()
.map(f -> f.toUri())
.map(Path::new)
.collect(Collectors.toSet()));
}
final List<URI> jarUrls =
ConfigUtils.decodeListFromConfig(configuration, PipelineOptions.JARS, URI::create);
if (jarUrls != null
&& YarnApplicationClusterEntryPoint.class.getName().equals(yarnClusterEntrypoint)) {
userJarFiles.addAll(jarUrls.stream().map(Path::new).collect(Collectors.toSet()));
}
// only for per job mode
if (jobGraph != null) {
for (Map.Entry<String, DistributedCache.DistributedCacheEntry> entry :
jobGraph.getUserArtifacts().entrySet()) {
// only upload local files
if (!Utils.isRemotePath(entry.getValue().filePath)) {
Path localPath = new Path(entry.getValue().filePath);
Tuple2<Path, Long> remoteFileInfo =
fileUploader.uploadLocalFileToRemote(localPath, entry.getKey());
jobGraph.setUserArtifactRemotePath(
entry.getKey(), remoteFileInfo.f0.toString());
}
}
jobGraph.writeUserArtifactEntriesToConfiguration();
}
if (providedLibDirs == null || providedLibDirs.isEmpty()) {
addLibFoldersToShipFiles(systemShipFiles);
}
// Register all files in provided lib dirs as local resources with public visibility
// and upload the remaining dependencies as local resources with APPLICATION visibility.
final List<String> systemClassPaths = fileUploader.registerProvidedLocalResources();
final List<String> uploadedDependencies =
fileUploader.registerMultipleLocalResources(
systemShipFiles.stream()
.map(e -> new Path(e.toURI()))
.collect(Collectors.toSet()),
Path.CUR_DIR,
LocalResourceType.FILE);
systemClassPaths.addAll(uploadedDependencies);
// upload and register ship-only files
// Plugin files only need to be shipped and should not be added to classpath.
if (providedLibDirs == null || providedLibDirs.isEmpty()) {
Set<File> shipOnlyFiles = new HashSet<>();
addPluginsFoldersToShipFiles(shipOnlyFiles);
fileUploader.registerMultipleLocalResources(
shipOnlyFiles.stream()
.map(e -> new Path(e.toURI()))
.collect(Collectors.toSet()),
Path.CUR_DIR,
LocalResourceType.FILE);
}
if (!shipArchives.isEmpty()) {
fileUploader.registerMultipleLocalResources(
shipArchives.stream().map(e -> new Path(e.toURI())).collect(Collectors.toSet()),
Path.CUR_DIR,
LocalResourceType.ARCHIVE);
}
// Upload and register user jars
final List<String> userClassPaths =
fileUploader.registerMultipleLocalResources(
userJarFiles,
userJarInclusion == YarnConfigOptions.UserJarInclusion.DISABLED
? ConfigConstants.DEFAULT_FLINK_USR_LIB_DIR
: Path.CUR_DIR,
LocalResourceType.FILE);
if (userJarInclusion == YarnConfigOptions.UserJarInclusion.ORDER) {
systemClassPaths.addAll(userClassPaths);
}
// normalize classpath by sorting
Collections.sort(systemClassPaths);
Collections.sort(userClassPaths);
// classpath assembler
StringBuilder classPathBuilder = new StringBuilder();
if (userJarInclusion == YarnConfigOptions.UserJarInclusion.FIRST) {
for (String userClassPath : userClassPaths) {
classPathBuilder.append(userClassPath).append(File.pathSeparator);
}
}
for (String classPath : systemClassPaths) {
classPathBuilder.append(classPath).append(File.pathSeparator);
}
// Setup jar for ApplicationMaster
final YarnLocalResourceDescriptor localResourceDescFlinkJar =
fileUploader.uploadFlinkDist(flinkJarPath);
classPathBuilder
.append(localResourceDescFlinkJar.getResourceKey())
.append(File.pathSeparator);
// write job graph to tmp file and add it to local resource
// TODO: server use user main method to generate job graph
if (jobGraph != null) {
File tmpJobGraphFile = null;
try {
tmpJobGraphFile = File.createTempFile(appId.toString(), null);
try (FileOutputStream output = new FileOutputStream(tmpJobGraphFile);
ObjectOutputStream obOutput = new ObjectOutputStream(output)) {
obOutput.writeObject(jobGraph);
}
final String jobGraphFilename = "job.graph";
configuration.setString(JOB_GRAPH_FILE_PATH, jobGraphFilename);
fileUploader.registerSingleLocalResource(
jobGraphFilename,
new Path(tmpJobGraphFile.toURI()),
"",
LocalResourceType.FILE,
true,
false);
classPathBuilder.append(jobGraphFilename).append(File.pathSeparator);
} catch (Exception e) {
LOG.warn("Add job graph to local resource fail.");
throw e;
} finally {
if (tmpJobGraphFile != null && !tmpJobGraphFile.delete()) {
LOG.warn("Fail to delete temporary file {}.", tmpJobGraphFile.toPath());
}
}
}
// Upload the flink configuration
// write out configuration file
File tmpConfigurationFile = null;
try {
tmpConfigurationFile = File.createTempFile(appId + "-flink-conf.yaml", null);
BootstrapTools.writeConfiguration(configuration, tmpConfigurationFile);
String flinkConfigKey = "flink-conf.yaml";
fileUploader.registerSingleLocalResource(
flinkConfigKey,
new Path(tmpConfigurationFile.getAbsolutePath()),
"",
LocalResourceType.FILE,
true,
true);
classPathBuilder.append("flink-conf.yaml").append(File.pathSeparator);
} finally {
if (tmpConfigurationFile != null && !tmpConfigurationFile.delete()) {
LOG.warn("Fail to delete temporary file {}.", tmpConfigurationFile.toPath());
}
}
if (userJarInclusion == YarnConfigOptions.UserJarInclusion.LAST) {
for (String userClassPath : userClassPaths) {
classPathBuilder.append(userClassPath).append(File.pathSeparator);
}
}
// To support Yarn Secure Integration Test Scenario
// In Integration test setup, the Yarn containers created by YarnMiniCluster does not have
// the Yarn site XML
// and KRB5 configuration files. We are adding these files as container local resources for
// the container
// applications (JM/TMs) to have proper secure cluster setup
Path remoteYarnSiteXmlPath = null;
if (System.getenv("IN_TESTS") != null) {
File f = new File(System.getenv("YARN_CONF_DIR"), Utils.YARN_SITE_FILE_NAME);
LOG.info(
"Adding Yarn configuration {} to the AM container local resource bucket",
f.getAbsolutePath());
Path yarnSitePath = new Path(f.getAbsolutePath());
remoteYarnSiteXmlPath =
fileUploader
.registerSingleLocalResource(
Utils.YARN_SITE_FILE_NAME,
yarnSitePath,
"",
LocalResourceType.FILE,
false,
false)
.getPath();
if (System.getProperty("java.security.krb5.conf") != null) {
configuration.set(
SecurityOptions.KERBEROS_KRB5_PATH,
System.getProperty("java.security.krb5.conf"));
}
}
Path remoteKrb5Path = null;
boolean hasKrb5 = false;
String krb5Config = configuration.get(SecurityOptions.KERBEROS_KRB5_PATH);
if (!StringUtils.isNullOrWhitespaceOnly(krb5Config)) {
final File krb5 = new File(krb5Config);
LOG.info(
"Adding KRB5 configuration {} to the AM container local resource bucket",
krb5.getAbsolutePath());
final Path krb5ConfPath = new Path(krb5.getAbsolutePath());
remoteKrb5Path =
fileUploader
.registerSingleLocalResource(
Utils.KRB5_FILE_NAME,
krb5ConfPath,
"",
LocalResourceType.FILE,
false,
false)
.getPath();
hasKrb5 = true;
}
Path remotePathKeytab = null;
String localizedKeytabPath = null;
String keytab = configuration.getString(SecurityOptions.KERBEROS_LOGIN_KEYTAB);
if (keytab != null) {
boolean localizeKeytab =
flinkConfiguration.getBoolean(YarnConfigOptions.SHIP_LOCAL_KEYTAB);
localizedKeytabPath =
flinkConfiguration.getString(YarnConfigOptions.LOCALIZED_KEYTAB_PATH);
if (localizeKeytab) {
// Localize the keytab to YARN containers via local resource.
LOG.info("Adding keytab {} to the AM container local resource bucket", keytab);
remotePathKeytab =
fileUploader
.registerSingleLocalResource(
localizedKeytabPath,
new Path(keytab),
"",
LocalResourceType.FILE,
false,
false)
.getPath();
} else {
// // Assume Keytab is pre-installed in the container.
localizedKeytabPath =
flinkConfiguration.getString(YarnConfigOptions.LOCALIZED_KEYTAB_PATH);
}
}
final JobManagerProcessSpec processSpec =
JobManagerProcessUtils.processSpecFromConfigWithNewOptionToInterpretLegacyHeap(
flinkConfiguration, JobManagerOptions.TOTAL_PROCESS_MEMORY);
final ContainerLaunchContext amContainer =
setupApplicationMasterContainer(yarnClusterEntrypoint, hasKrb5, processSpec);
// setup security tokens
if (UserGroupInformation.isSecurityEnabled()) {
// set HDFS delegation tokens when security is enabled
LOG.info("Adding delegation token to the AM container.");
List<Path> yarnAccessList =
ConfigUtils.decodeListFromConfig(
configuration, YarnConfigOptions.YARN_ACCESS, Path::new);
Utils.setTokensFor(
amContainer,
ListUtils.union(yarnAccessList, fileUploader.getRemotePaths()),
yarnConfiguration);
}
amContainer.setLocalResources(fileUploader.getRegisteredLocalResources());
fileUploader.close();
// Setup CLASSPATH and environment variables for ApplicationMaster
final Map<String, String> appMasterEnv = new HashMap<>();
// set user specified app master environment variables
appMasterEnv.putAll(
ConfigurationUtils.getPrefixedKeyValuePairs(
ResourceManagerOptions.CONTAINERIZED_MASTER_ENV_PREFIX, configuration));
// set Flink app class path
appMasterEnv.put(YarnConfigKeys.ENV_FLINK_CLASSPATH, classPathBuilder.toString());
// set Flink on YARN internal configuration values
appMasterEnv.put(YarnConfigKeys.FLINK_DIST_JAR, localResourceDescFlinkJar.toString());
appMasterEnv.put(YarnConfigKeys.ENV_APP_ID, appId.toString());
appMasterEnv.put(YarnConfigKeys.ENV_CLIENT_HOME_DIR, fileUploader.getHomeDir().toString());
appMasterEnv.put(
YarnConfigKeys.ENV_CLIENT_SHIP_FILES,
encodeYarnLocalResourceDescriptorListToString(
fileUploader.getEnvShipResourceList()));
appMasterEnv.put(
YarnConfigKeys.FLINK_YARN_FILES,
fileUploader.getApplicationDir().toUri().toString());
// https://github.com/apache/hadoop/blob/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/YarnApplicationSecurity.md#identity-on-an-insecure-cluster-hadoop_user_name
appMasterEnv.put(
YarnConfigKeys.ENV_HADOOP_USER_NAME,
UserGroupInformation.getCurrentUser().getUserName());
if (localizedKeytabPath != null) {
appMasterEnv.put(YarnConfigKeys.LOCAL_KEYTAB_PATH, localizedKeytabPath);
String principal = configuration.getString(SecurityOptions.KERBEROS_LOGIN_PRINCIPAL);
appMasterEnv.put(YarnConfigKeys.KEYTAB_PRINCIPAL, principal);
if (remotePathKeytab != null) {
appMasterEnv.put(YarnConfigKeys.REMOTE_KEYTAB_PATH, remotePathKeytab.toString());
}
}
// To support Yarn Secure Integration Test Scenario
if (remoteYarnSiteXmlPath != null) {
appMasterEnv.put(
YarnConfigKeys.ENV_YARN_SITE_XML_PATH, remoteYarnSiteXmlPath.toString());
}
if (remoteKrb5Path != null) {
appMasterEnv.put(YarnConfigKeys.ENV_KRB5_PATH, remoteKrb5Path.toString());
}
// set classpath from YARN configuration
Utils.setupYarnClassPath(yarnConfiguration, appMasterEnv);
amContainer.setEnvironment(appMasterEnv);
// Set up resource type requirements for ApplicationMaster
Resource capability = Records.newRecord(Resource.class);
capability.setMemory(clusterSpecification.getMasterMemoryMB());
capability.setVirtualCores(
flinkConfiguration.getInteger(YarnConfigOptions.APP_MASTER_VCORES));
final String customApplicationName = customName != null ? customName : applicationName;
appContext.setApplicationName(customApplicationName);
appContext.setApplicationType(applicationType != null ? applicationType : "Apache Flink");
appContext.setAMContainerSpec(amContainer);
appContext.setResource(capability);
// Set priority for application
int priorityNum = flinkConfiguration.getInteger(YarnConfigOptions.APPLICATION_PRIORITY);
if (priorityNum >= 0) {
Priority priority = Priority.newInstance(priorityNum);
appContext.setPriority(priority);
}
if (yarnQueue != null) {
appContext.setQueue(yarnQueue);
}
setApplicationNodeLabel(appContext);
setApplicationTags(appContext);
// add a hook to clean up in case deployment fails
Thread deploymentFailureHook =
new DeploymentFailureHook(yarnApplication, fileUploader.getApplicationDir());
Runtime.getRuntime().addShutdownHook(deploymentFailureHook);
LOG.info("Submitting application master " + appId);
yarnClient.submitApplication(appContext);
LOG.info("Waiting for the cluster to be allocated");
final long startTime = System.currentTimeMillis();
ApplicationReport report;
YarnApplicationState lastAppState = YarnApplicationState.NEW;
loop:
while (true) {
try {
report = yarnClient.getApplicationReport(appId);
} catch (IOException e) {
throw new YarnDeploymentException("Failed to deploy the cluster.", e);
}
YarnApplicationState appState = report.getYarnApplicationState();
LOG.debug("Application State: {}", appState);
switch (appState) {
case FAILED:
case KILLED:
throw new YarnDeploymentException(
"The YARN application unexpectedly switched to state "
+ appState
+ " during deployment. \n"
+ "Diagnostics from YARN: "
+ report.getDiagnostics()
+ "\n"
+ "If log aggregation is enabled on your cluster, use this command to further investigate the issue:\n"
+ "yarn logs -applicationId "
+ appId);
// break ..
case RUNNING:
LOG.info("YARN application has been deployed successfully.");
break loop;
case FINISHED:
LOG.info("YARN application has been finished successfully.");
break loop;
default:
if (appState != lastAppState) {
LOG.info("Deploying cluster, current state " + appState);
}
if (System.currentTimeMillis() - startTime > 60000) {
LOG.info(
"Deployment took more than 60 seconds. Please check if the requested resources are available in the YARN cluster");
}
}
lastAppState = appState;
Thread.sleep(250);
}
// since deployment was successful, remove the hook
ShutdownHookUtil.removeShutdownHook(deploymentFailureHook, getClass().getSimpleName(), LOG);
return report;
}
Table API
Table API比DataStream API更方便一些。以下是实时处理Kafka的数据流。
public class FlinkTemperatureAverage {
public static void main(String[] args) throws Exception {
// 设置流执行环境
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
// 创建 TableEnvironment
StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env);
// 定义表结构
tableEnv.executeSql("CREATE TABLE sensor_readings (timestamp TIMESTAMP(3) METADATA FROM 'timestamp', temperature DOUBLE) WITH ('connector' = 'kafka', 'topic' = 'input_topic', 'properties.bootstrap.servers' = 'localhost:9092', 'format' = 'json')");
// 创建输出表
tableEnv.executeSql("CREATE TABLE temperature_averages (window_start TIMESTAMP(3), window_end TIMESTAMP(3), avg_temperature DOUBLE) WITH ('connector' = 'kafka', 'topic' = 'output_topic', 'properties.bootstrap.servers' = 'localhost:9092', 'format' = 'json')");
// 实时计算每分钟内的平均温度
tableEnv.executeSql("INSERT INTO temperature_averages SELECT TUMBLE_START(timestamp, INTERVAL '1' MINUTE) AS window_start, TUMBLE_END(timestamp, INTERVAL '1' MINUTE) AS window_end, AVG(temperature) AS avg_temperature FROM sensor_readings GROUP BY TUMBLE(timestamp, INTERVAL '1' MINUTE)");
// 启动 Flink 任务
env.execute("Flink Temperature Average Calculation");
}
}
窗口
就像Hive SQL中的开窗一样,Flink对于聚合分析也需要开启窗口。
- 滚动窗口(Tumbling Windows)
固定大小的、不重叠的窗口。例如,每5分钟一个窗口。 - 滑动窗口(Sliding Windows)
固定大小的、但可以重叠的窗口。例如,每1分钟滑动一次,每次窗口大小为5分钟。 - 会话窗口(Session Windows)
基于活动时间的窗口,即当数据在一定时间间隔内没有到达时,窗口会关闭。这种窗口适用于处理活动间隔的数据,如用户会话。 - 全局窗口(Global Windows)
一个全局窗口会包含流中的所有元素,并且通常需要一个触发器(Trigger)来定义何时应该对这个窗口的元素进行计算。 - 计数窗口(Count Windows)
基于元素数量的窗口,当窗口内的元素数量达到指定值时,就会触发计算。
下面是各种窗口之间的区别
数据源
Flink支持的数据源有:文件系统、Kafka、RabbitMQ、JDBC数据库、Socket。
还支持自定义数据源,只要实现SourceFunction和SinkFunction接口就可以了。
Flink CDC
Flink CDC(Flink Change Data Capture)基于Flink框架,实现了对数据源变更数据的捕捉和处理。
单独的开源项目https://github.com/apache/flink-cdc
Flink CDC内置了CDC引擎debezium,通过监听binlog等使得捕捉数据的能力比基于SourceFunction的查询方案更加高效。debezium是可以作为服务独立部署的,只是Flink CDC将其作为插件内置进来了。
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