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From Elkhan Dadashov <>
Subject Re: SparkLauncher not notified about finished job - hangs infinitely.
Date Fri, 31 Jul 2015 17:02:07 GMT
Hi Tomasz,

*Answer to your 1st question*:

Clear/read the error (spark.getErrorStream()) and output
(spark.getInputStream()) stream buffers before you call spark.waitFor(), it
would be better to clear/read them with 2 different threads. Then it should
work fine.

As Spark job is launched as subprocess, and according to Oracle

"By default, the created subprocess does not have its own terminal or
console. All its standard I/O (i.e. stdin, stdout, stderr) operations will
be redirected to the parent process, where they can be accessed via the
streams obtained using the methodsgetOutputStream(), getInputStream(), and
getErrorStream(). The parent process uses these streams to feed input to
and get output from the subprocess. Because some native platforms only
provide limited buffer size for standard input and output streams, failure
to promptly write the input stream or read the output stream of the
subprocess may cause the subprocess to block, or even deadlock.

On Fri, Jul 31, 2015 at 2:45 AM, Tomasz GuziaƂek <> wrote:

> 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
> successfully submitted to YARN and executes successfully (it is visible in
> the YARN UI, reported as SUCCESS and PI value 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 value is not printed out).
> The log of the container can be found here:
> I tried to execute the submitting application both with Oracle Java 8 and
> 7.
> Any hints what might be wrong?
> Best regards,
> Tomasz


Best regards,
Elkhan Dadashov

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