HelloWorld.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.twill.example.yarn;

import org.apache.hadoop.yarn.conf.YarnConfiguration;
import org.apache.twill.api.AbstractTwillRunnable;
import org.apache.twill.api.TwillController;
import org.apache.twill.api.TwillRunnerService;
import org.apache.twill.api.logging.PrinterLogHandler;
import org.apache.twill.common.Services;
import org.apache.twill.yarn.YarnTwillRunnerService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.PrintWriter;
import java.util.concurrent.ExecutionException;

/**
 * Hello World example using twill-yarn to run a TwillApplication over YARN.
 */
public class HelloWorld {
  public static Logger LOG = LoggerFactory.getLogger(HelloWorld.class);

  /**
   * Hello World runnable that is provided to TwillRunnerService to be run.
   */
  private static class HelloWorldRunnable extends AbstractTwillRunnable {
    @Override
    public void run() {
      LOG.info("Hello World. My first distributed application.");
    }

    @Override
    public void stop() {
    }
  }

  public static void main(String[] args) {
    if (args.length < 1) {
      System.err.println("Arguments format: <host:port of zookeeper server>");
    }

    String zkStr = args[0];

    final TwillRunnerService twillRunner =
      new YarnTwillRunnerService(
        new YarnConfiguration(), zkStr);
    twillRunner.startAndWait();

    final TwillController controller =
      twillRunner.prepare(new HelloWorldRunnable())
        .addLogHandler(new PrinterLogHandler(new PrintWriter(System.out, true)))
        .start();

    Runtime.getRuntime().addShutdownHook(new Thread() {
      @Override
      public void run() {
        controller.stopAndWait();
        twillRunner.stopAndWait();
      }
    });

    try {
      Services.getCompletionFuture(controller).get();
    } catch (InterruptedException e) {
      e.printStackTrace();
    } catch (ExecutionException e) {
      e.printStackTrace();
    }
  }
}