Harnessing the power of YARN with Apache Twill
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This document discusses Apache Twill, which aims to simplify developing distributed applications on YARN. Twill provides a Java thread-like programming model for YARN applications, avoiding the complexity of directly using YARN APIs. Key features of Twill include real-time logging, resource reporting, state recovery, elastic scaling, command messaging between tasks, service discovery, and support for executing bundled JAR applications on YARN. Twill handles communication with YARN and the Application Master while providing an easy-to-use API for application developers.
![ApacheCon 2014
Hello World
public class HelloWorld {
static Logger LOG = LoggerFactory.getLogger(HelloWorld.class);
static class HelloWorldRunnable extends AbstractTwillRunnable {
@Override
public void run() {
LOG.info("Hello World");
}
}
public static void main(String[] args) throws Exception {
YarnConfiguration conf = new YarnConfiguration();
TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181");
runner.startAndWait();
TwillController controller = runner.prepare(new HelloWorldRunnable())
.start();
Services.getCompletionFuture(controller).get();
}](https://image.slidesharecdn.com/twillapachecon2014-140422025503-phpapp02/85/Harnessing-the-power-of-YARN-with-Apache-Twill-29-320.jpg)
![ApacheCon 2014
Hello World
public class HelloWorld {
static Logger LOG = LoggerFactory.getLogger(HelloWorld.class);
static class HelloWorldRunnable extends AbstractTwillRunnable {
@Override
public void run() {
LOG.info("Hello World");
}
}
public static void main(String[] args) throws Exception {
YarnConfiguration conf = new YarnConfiguration();
TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181");
runner.startAndWait();
TwillController controller = runner.prepare(new HelloWorldRunnable())
.start();
Services.getCompletionFuture(controller).get();
}](https://image.slidesharecdn.com/twillapachecon2014-140422025503-phpapp02/85/Harnessing-the-power-of-YARN-with-Apache-Twill-30-320.jpg)
![ApacheCon 2014
Hello World
public class HelloWorld {
static Logger LOG = LoggerFactory.getLogger(HelloWorld.class);
static class HelloWorldRunnable extends AbstractTwillRunnable {
@Override
public void run() {
LOG.info("Hello World");
}
}
public static void main(String[] args) throws Exception {
YarnConfiguration conf = new YarnConfiguration();
TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181");
runner.startAndWait();
TwillController controller = runner.prepare(new HelloWorldRunnable())
.start();
Services.getCompletionFuture(controller).get();
}](https://image.slidesharecdn.com/twillapachecon2014-140422025503-phpapp02/85/Harnessing-the-power-of-YARN-with-Apache-Twill-31-320.jpg)
![ApacheCon 2014
Hello World
public class HelloWorld {
static Logger LOG = LoggerFactory.getLogger(HelloWorld.class);
static class HelloWorldRunnable extends AbstractTwillRunnable {
@Override
public void run() {
LOG.info("Hello World");
}
}
public static void main(String[] args) throws Exception {
YarnConfiguration conf = new YarnConfiguration();
TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181");
runner.startAndWait();
TwillController controller = runner.prepare(new HelloWorldRunnable())
.start();
Services.getCompletionFuture(controller).get();
}](https://image.slidesharecdn.com/twillapachecon2014-140422025503-phpapp02/85/Harnessing-the-power-of-YARN-with-Apache-Twill-32-320.jpg)
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Harnessing the power of YARN with Apache Twill
- 1. Harnessing the Power of YARN with Apache Twill Terence Yim [email protected] @chtyim
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- 11. ApacheCon 2014 The Answer is YARN • Resource Manager of Hadoop 2.0! • Separates ! • Resource Management! • Programming Paradigm! • (Almost) any distributed app in Hadoop cluster! • Application Master to negotiate resources
- 12. ApacheCon 2014 A YARN Application data data data data data data YARN Resource Manager App Master
- 13. ApacheCon 2014 A Multi-Purpose Cluster t AM AM AM AM AM YARN Resource Manager
- 14. ApacheCon 2014 Node Mgr Node Mgr YARN - How it works YARN Resource Manager YARN! Client 1. 1. Submit App Master AM 2. 2. Start App Master in a Container 3. 3. Request Containers Task TaskTask 4. 4. Start Tasks in Containers
- 15. ApacheCon 2014 Starting the App Master YARN Resource Manager YARN! Client Node Mgr . . . Local file system Local file system HDFS distributed file system Local file system! ! AM AM.jar AM.jar 1) copy to HDFS AM.jar 2) copy to local 3) load Node Mgr
- 16. ApacheCon 2014 The YARN Client 1. Connect to the Resource Manager.! 2. Request a new application ID.! 3. Create a submission context and a container launch context.! 4. Define the local resources for the AM.! 5. Define the environment for the AM.! 6. Define the command to run for the AM.! 7. Define the resource limits for the AM.! 8. Submit the request to start the app master.
- 17. ApacheCon 2014 Writing the YARN Client 1. Connect to the Resource Manager: YarnConfiguration yarnConf = new YarnConfiguration(conf); InetSocketAddress rmAddress = NetUtils.createSocketAddr(yarnConf.get( YarnConfiguration.RM_ADDRESS, YarnConfiguration.DEFAULT_RM_ADDRESS)); LOG.info("Connecting to ResourceManager at " + rmAddress); configuration rmServerConf = new Configuration(conf); rmServerConf.setClass( YarnConfiguration.YARN_SECURITY_INFO, ClientRMSecurityInfo.class, SecurityInfo.class); ClientRMProtocol resourceManager = ((ClientRMProtocol) rpc.getProxy( ClientRMProtocol.class, rmAddress, appsManagerServerConf)); !
- 18. ApacheCon 2014 Writing the YARN Client 2) Request an application ID: GetNewApplicationRequest request = Records.newRecord(GetNewApplicationRequest.class); GetNewApplicationResponse response = resourceManager.getNewApplication(request); LOG.info("Got new ApplicationId=" + response.getApplicationId()); 3) Create a submission context and a launch context ! ApplicationSubmissionContext appContext = Records.newRecord(ApplicationSubmissionContext.class); appContext.setApplicationId(appId); appContext.setApplicationName(appName); ContainerLaunchContext amContainer = Records.newRecord(ContainerLaunchContext.class);
- 19. ApacheCon 2014 Writing the YARN Client 4. Define the local resources: Map<String, LocalResource> localResources = Maps.newHashMap(); // assume the AM jar is here: Path jarPath; // <- known path to jar file ! // Create a resource with location, time stamp and file length LocalResource amJarRsrc = Records.newRecord(LocalResource.class); amJarRsrc.setType(LocalResourceType.FILE); amJarRsrc.setResource(ConverterUtils.getYarnUrlFromPath(jarPath)); FileStatus jarStatus = fs.getFileStatus(jarPath); amJarRsrc.setTimestamp(jarStatus.getModificationTime()); amJarRsrc.setSize(jarStatus.getLen()); localResources.put("AppMaster.jar", amJarRsrc); ! amContainer.setLocalResources(localResources);
- 20. ApacheCon 2014 Writing the YARN Client 5. Define the environment: // Set up the environment needed for the launch context Map<String, String> env = new HashMap<String, String>(); ! // Setup the classpath needed. // Assuming our classes are available as local resources in the // working directory, we need to append "." to the path. String classPathEnv = "$CLASSPATH:./*:"; env.put("CLASSPATH", classPathEnv); ! // setup more environment env.put(...); ! amContainer.setEnvironment(env); !
- 21. ApacheCon 2014 Writing the YARN Client 6. Define the command to run for the AM: // Construct the command to be executed on the launched container String command = "${JAVA_HOME}" + /bin/java" + " MyAppMaster" + " arg1 arg2 arg3" + " 1>" + ApplicationConstants.LOG_DIR_EXPANSION + "/stdout" + " 2>" + ApplicationConstants.LOG_DIR_EXPANSION + "/stderr"; ! List<String> commands = new ArrayList<String>(); commands.add(command); ! // Set the commands into the container spec amContainer.setCommands(commands); !
- 22. ApacheCon 2014 Writing the YARN Client 7. Define the resource limits for the AM: // Define the resource requirements for the container. // For now, YARN only supports memory constraints. // If the process takes more memory, it is killed by the framework. Resource capability = Records.newRecord(Resource.class); capability.setMemory(amMemory); amContainer.setResource(capability); // Set the container launch content into the submission context appContext.setAMContainerSpec(amContainer); ! ! ! !
- 23. ApacheCon 2014 Writing the YARN Client 8. Submit the request to start the app master: // Create the request to send to the Resource Manager SubmitApplicationRequest appRequest = Records.newRecord(SubmitApplicationRequest.class); appRequest.setApplicationSubmissionContext(appContext); ! // Submit the application to the ApplicationsManager resourceManager.submitApplication(appRequest); ! ! ! ! !
- 24. ApacheCon 2014 Node Mgr Node Mgr YARN - How it works YARN Resource Manager YARN! Client 1. 1. Submit App Master AM 2. 2. Start App Master in a Container 3. 3. Request Containers Task TaskTask 4. 4. Start Tasks in Containers
- 25. ApacheCon 2014 YARN is complex • Three different protocols to learn! • Client -> RM, AM -> RM, AM -> NM! • Asynchronous protocols! • Full Power at the expense of simplicity! • Duplication of code ! • App masters! • YARN clients
- 26. Can it be easier?
- 27. ApacheCon 2014 YARN App vs Multi-threaded App YARN Application Multi-threaded Java Application YARN Client java command to launch application with options and arguments Application Master main() method preparing threads Task in Container Runnable implementation, each runs in its own Thread
- 28. ApacheCon 2014 Apache Twill • Adds simplicity to the power of YARN! • Java thread-like programming model! • Incubated at Apache Software Foundation (Nov 2013)! • Current release: 0.2.0-incubating
- 29. ApacheCon 2014 Hello World public class HelloWorld { static Logger LOG = LoggerFactory.getLogger(HelloWorld.class); static class HelloWorldRunnable extends AbstractTwillRunnable { @Override public void run() { LOG.info("Hello World"); } } public static void main(String[] args) throws Exception { YarnConfiguration conf = new YarnConfiguration(); TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181"); runner.startAndWait(); TwillController controller = runner.prepare(new HelloWorldRunnable()) .start(); Services.getCompletionFuture(controller).get(); }
- 30. ApacheCon 2014 Hello World public class HelloWorld { static Logger LOG = LoggerFactory.getLogger(HelloWorld.class); static class HelloWorldRunnable extends AbstractTwillRunnable { @Override public void run() { LOG.info("Hello World"); } } public static void main(String[] args) throws Exception { YarnConfiguration conf = new YarnConfiguration(); TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181"); runner.startAndWait(); TwillController controller = runner.prepare(new HelloWorldRunnable()) .start(); Services.getCompletionFuture(controller).get(); }
- 31. ApacheCon 2014 Hello World public class HelloWorld { static Logger LOG = LoggerFactory.getLogger(HelloWorld.class); static class HelloWorldRunnable extends AbstractTwillRunnable { @Override public void run() { LOG.info("Hello World"); } } public static void main(String[] args) throws Exception { YarnConfiguration conf = new YarnConfiguration(); TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181"); runner.startAndWait(); TwillController controller = runner.prepare(new HelloWorldRunnable()) .start(); Services.getCompletionFuture(controller).get(); }
- 32. ApacheCon 2014 Hello World public class HelloWorld { static Logger LOG = LoggerFactory.getLogger(HelloWorld.class); static class HelloWorldRunnable extends AbstractTwillRunnable { @Override public void run() { LOG.info("Hello World"); } } public static void main(String[] args) throws Exception { YarnConfiguration conf = new YarnConfiguration(); TwillRunnerService runner = new YarnTwillRunnerService(conf, "localhost:2181"); runner.startAndWait(); TwillController controller = runner.prepare(new HelloWorldRunnable()) .start(); Services.getCompletionFuture(controller).get(); }
- 33. Twill is easy.
- 34. ApacheCon 2014 Architecture ! ! Twill! Client! ! ! …! ! ! Twill Runnable Twill Runner Twill Runnable This is the only programming interface you need Node Mgr Twill! AM YARN Resource Manager Task Task Task Task Task Task Node Mgr Node Mgr Node Mgr 1. 2. 3. 4.
- 35. ApacheCon 2014 Twill Application What if my app needs more than one type of task?! ! ! ! ! ! ! !
- 36. ApacheCon 2014 Twill Application What if my app needs more than one type of task?! • Define a TwillApplication with multiple TwillRunnables inside:! public class MyTwillApplication implements TwillApplication { ! @Override public TwillSpecification configure() { return TwillSpecification.Builder.with() .setName("Search") .withRunnable() .add("crawler", new CrawlerTwillRunnable()).noLocalFiles() .add("indexer", new IndexerTwillRunnable()).noLocalFiles() .anyOrder() .build(); } }
- 37. ApacheCon 2014 Features • Real-time logging! • Resource report! • State recovery! • Elastic scaling! • Command messages! • Service discovery! • Bundle jar execution
- 38. ApacheCon 2014 Real-Time Logging ! ! Twill! Client! Twill Runner LogHandler to receive logs from all runnables Node Mgr AM+ Kafka YARN Resource Manager Task Task Task Task Task Task Node Mgr Node Mgr Node Mgr log stream log log appender to send logs to Kafka
- 39. ApacheCon 2014 Real-time Logging TwillController controller = runner.prepare(new HelloWorldRunnable()) .addLogHandler(new PrinterLogHandler( new PrintWriter(System.out, true))) .start(); ! OR ! ! controller.addLogHandler(new PrinterLogHandler( new PrintWriter(System.out, true))); ! !
- 40. ApacheCon 2014 Resource Report • Twill Application Master exposes HTTP endpoint! • Resource information for each container (AM and Runnables)! • Memory and virtual core! • Number of live instances for each Runnable! • Hostname of the container is running on! • Container ID! • Registered as AM tracking URL
- 41. ApacheCon 2014 Resource Report • Programmatic access to resource report.! ! ! ResourceReport report = controller.getResourceReport(); Collection<TwillRunResources> resources = report.getRunnableResource("MyRunnable"); ! ! ! !
- 42. ApacheCon 2014 State Recovery • What happens to the Twill app if the client terminates?! • It keeps running! • Can a new client take over control?
- 43. ApacheCon 2014 ! ! Twill! Client! State Recovery Twill Runner Recover state from ZooKeeper Node Mgr AM+ Kafka YARN Resource Manager Task Task Task Task Task Task Node Mgr Node Mgr Node Mgr ZooKeeper ZooKeeper ZooKeeper state
- 44. ApacheCon 2014 State Recovery • All live instances of an application! ! ! Iterable<TwillController> controllers = runner.lookup("HelloWorld");! • A particular live instance! ! ! TwillController controller = runner.lookup(“HelloWorld”, RunIds.fromString("lastRunId")); • All live instances of all applications! ! ! Iterable<LiveInfo> liveInfos = runner.lookupLive();
- 45. ApacheCon 2014 ! ! Twill! Client! Command Messages Twill Runner Send command message to runnables Node Mgr AM+ Kafka YARN Resource Manager Task Task Task Task Task Task Node Mgr Node Mgr Node Mgr ZooKeeper ZooKeeper ZooKeeper message
- 46. ApacheCon 2014 Command Messages • Send to all Runnables:! ! ListenableFuture<Command> completion = controller.sendCommand( Command.Builder.of("gc").build()); • Send to the “indexer” Runnable:! ! ListenableFuture<Command> completion = controller.sendCommand("indexer", Command.Builder.of("flush").build()); • The Runnable implementation defines how to handle it:! ! void handleCommand(Command command) throws Exception;
- 47. ApacheCon 2014 Elastic Scaling • Change the instance count of a live runnable! ! ListenableFuture<Integer> completion = controller.changeInstances("crawler", 10); // Wait for change complete completion.get(); • Implemented by a command message to the AM.! !
- 48. ApacheCon 2014 Service Discovery • Running a service in Twill! • What host/port should a client connect to?
- 49. ApacheCon 2014 ! ! Twill! Client! Service Discovery Twill Runner Watch for change in discovery nodes Node Mgr AM+ Kafka YARN Resource Manager Task Task Task Task Task Task Node Mgr Node Mgr Node Mgr ZooKeeper ZooKeeper ZooKeeper Service changes Register service
- 50. ApacheCon 2014 Service Discovery • In TwillRunnable, register as a named service:! ! @Override public void initialize(TwillContext context) { // Starts server on random port int port = startServer(); context.announce("service", port); } • Discover by service name on client side:! ! ServiceDiscovered serviceDiscovered = controller.discoverService(“service"); !
- 51. ApacheCon 2014 Bundle Jar Execution • Different library dependencies than Twill! • Run existing application in YARN
- 52. ApacheCon 2014 Bundle Jar Execution • Bundle Jar contains classes and all libraries depended on inside a jar.! ! MyMain.class MyRecord.class lib/guava-16.0.1.jar lib/netty-all-4.0.17.jar • Easy to create with build tools! • Maven - maven-bundle-plugin! • Gradle - apply plugin: 'osgi' !
- 53. ApacheCon 2014 Bundle Jar Execution • Execute with BundledJarRunnable! • See BundledJarExample in the source tree.! ! java org.apache.twill.example.yarn.BundledJarExample <zkConnectStr> <bundleJarPath> <mainClass> <args…> ! • Successfully run Presto on YARN! • Non-intrusive, no code modification for Presto! • Simple maven project to use Presto in embedded way and create Bundle Jar! !
- 54. ApacheCon 2014 The Road Ahead • Scripts for easy life cycle management and scaling! • Distributed coordination within application! • Remote debugging! • Non-Java application! • Suspend and resume application! • Metrics! • Local runner service! • …
- 55. ApacheCon 2014 Summary • YARN is powerful! • Allows applications other than M/R in Hadoop cluster! • YARN is complex! • Complex protocols, boilerplate code! • Twill makes YARN easy! • Java Thread-like runnables! • Add-on features required by many distributed applications! • Productivity Boost! • Developers can focus on application logic
- 56. ApacheCon 2014 Thank You • Twill is Open Source and needs your contributions! • twill.incubator.apache.org! • [email protected]! ! • Continuuity is hiring! • continuuity.com/careers