Spark Launcher waiting for job completion infinitely

问题

I am trying to submit a JAR with Spark job into the YARN cluster from Java code. I am using SparkLauncher to submit SparkPi example:

Process spark = new SparkLauncher()
    .setAppResource("C:\\spark-1.4.1-bin-hadoop2.6\\lib\\spark-examples-1.4.1-hadoop2.6.0.jar")
    .setMainClass("org.apache.spark.examples.SparkPi")
    .setMaster("yarn-cluster")
    .launch();
System.out.println("Waiting for finish...");
int exitCode = spark.waitFor();
System.out.println("Finished! Exit code:" + exitCode);

There are two problems:

1. While submitting in "yarn-cluster" mode, the application is sucessfully submitted to YARN and executes successfully (it is visible in the YARN UI, reported as SUCCESS and pi is printed in the output). However, the submitting application is never notified that processing is finished - it hangs infinitely after printing "Waiting to finish..." The log of the container can be found here
2. While submitting in "yarn-client" mode, the application does not appear in YARN UI and the submitting application hangs at "Waiting to finish..." When hanging code is killed, the application shows up in YARN UI and it is reported as SUCCESS, but the output is empty (pi is not printed out). The log of the container can be found here

I tried to execute the submitting application both with Oracle Java 7 and 8.

回答1:

I got help in the Spark mailing list. The key is to read / clear getInputStream and getErrorStream() on the Process. The child process might fill up the buffer and cause a deadlock - see Oracle docs regarding Process. The streams should be read in separate threads:

Process spark = new SparkLauncher()
    .setSparkHome("C:\\spark-1.4.1-bin-hadoop2.6")
    .setAppResource("C:\\spark-1.4.1-bin-hadoop2.6\\lib\\spark-examples-1.4.1-hadoop2.6.0.jar")
    .setMainClass("org.apache.spark.examples.SparkPi").setMaster("yarn-cluster").launch();

InputStreamReaderRunnable inputStreamReaderRunnable = new InputStreamReaderRunnable(spark.getInputStream(), "input");
Thread inputThread = new Thread(inputStreamReaderRunnable, "LogStreamReader input");
inputThread.start();

InputStreamReaderRunnable errorStreamReaderRunnable = new InputStreamReaderRunnable(spark.getErrorStream(), "error");
Thread errorThread = new Thread(errorStreamReaderRunnable, "LogStreamReader error");
errorThread.start();

System.out.println("Waiting for finish...");
int exitCode = spark.waitFor();
System.out.println("Finished! Exit code:" + exitCode);

where InputStreamReaderRunnable class is:

public class InputStreamReaderRunnable implements Runnable {

    private BufferedReader reader;

    private String name;

    public InputStreamReaderRunnable(InputStream is, String name) {
        this.reader = new BufferedReader(new InputStreamReader(is));
        this.name = name;
    }

    public void run() {
        System.out.println("InputStream " + name + ":");
        try {
            String line = reader.readLine();
            while (line != null) {
                System.out.println(line);
                line = reader.readLine();
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

回答2:

Since this is an old post, i would like to add an update that might help whom ever read this post after. In spark 1.6.0 there are some added functions in SparkLauncher class. Which is:

def startApplication(listeners: <repeated...>[Listener]): SparkAppHandle

http://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.launcher.SparkLauncher

You can run the application with out the need for additional threads for the stdout and stderr handling plush there is a nice status reporting of the application running. Use this code:

  val env = Map(
      "HADOOP_CONF_DIR" -> hadoopConfDir,
      "YARN_CONF_DIR" -> yarnConfDir
    )
  val handler = new SparkLauncher(env.asJava)
      .setSparkHome(sparkHome)
      .setAppResource("Jar/location/.jar")
      .setMainClass("path.to.the.main.class")
      .setMaster("yarn-client")
      .setConf("spark.app.id", "AppID if you have one")
      .setConf("spark.driver.memory", "8g")
      .setConf("spark.akka.frameSize", "200")
      .setConf("spark.executor.memory", "2g")
      .setConf("spark.executor.instances", "32")
      .setConf("spark.executor.cores", "32")
      .setConf("spark.default.parallelism", "100")
      .setConf("spark.driver.allowMultipleContexts","true")
      .setVerbose(true)
      .startApplication()
println(handle.getAppId)
println(handle.getState)

You can keep enquering the state if the spark application until it give success. For information about how the Spark Launcher server works in 1.6.0. see this link: https://github.com/apache/spark/blob/v1.6.0/launcher/src/main/java/org/apache/spark/launcher/LauncherServer.java

回答3:

I implemented using CountDownLatch, and it works as expected. This is for SparkLauncher version 2.0.1 and it works in Yarn-cluster mode too.

    ...
final CountDownLatch countDownLatch = new CountDownLatch(1);
SparkAppListener sparkAppListener = new SparkAppListener(countDownLatch);
SparkAppHandle appHandle = sparkLauncher.startApplication(sparkAppListener);
Thread sparkAppListenerThread = new Thread(sparkAppListener);
sparkAppListenerThread.start();
long timeout = 120;
countDownLatch.await(timeout, TimeUnit.SECONDS);    
    ...

private static class SparkAppListener implements SparkAppHandle.Listener, Runnable {
    private static final Log log = LogFactory.getLog(SparkAppListener.class);
    private final CountDownLatch countDownLatch;
    public SparkAppListener(CountDownLatch countDownLatch) {
        this.countDownLatch = countDownLatch;
    }
    @Override
    public void stateChanged(SparkAppHandle handle) {
        String sparkAppId = handle.getAppId();
        State appState = handle.getState();
        if (sparkAppId != null) {
            log.info("Spark job with app id: " + sparkAppId + ",\t State changed to: " + appState + " - "
                    + SPARK_STATE_MSG.get(appState));
        } else {
            log.info("Spark job's state changed to: " + appState + " - " + SPARK_STATE_MSG.get(appState));
        }
        if (appState != null && appState.isFinal()) {
            countDownLatch.countDown();
        }
    }
    @Override
    public void infoChanged(SparkAppHandle handle) {}
    @Override
    public void run() {}
}

来源：https://stackoverflow.com/questions/31754328/spark-launcher-waiting-for-job-completion-infinitely