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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4340) "hadoop jar" always returns exit code 0 (success) to the shell when jar throws a fatal exception
Date Mon, 06 Oct 2008 09:59:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12637057#action_12637057
] 

Steve Loughran commented on HADOOP-4340:
----------------------------------------

Looking at the stack trace, the cause is t

JobShell.main() doesn't set an exit code

  public static void main(String[] argv) throws Exception {
    JobShell jshell = new JobShell();
    ToolRunner.run(jshell, argv);
  }

It should go System.exit(ToolRunner.run(...)))

question is, what is going to break?

> "hadoop jar" always returns exit code 0 (success) to the shell when jar throws a fatal
exception 
> -------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-4340
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4340
>             Project: Hadoop Core
>          Issue Type: Bug
>    Affects Versions: 0.18.1, 0.19.0, 0.20.0
>         Environment: Ubuntu 8.04 Server, 7 Hadoop nodes, GNU bash, version 3.2.39(1)-release
(i486-pc-linux-gnu)
>            Reporter: David Litster
>
> Running "hadoop jar" always returns 0 (success) when the jar dies with a stack trace.
 As an example, run these commands:
> /usr/local/hadoop/bin/hadoop jar /usr/local/hadoop/hadoop-0.18.1-examples.jar pi 10 10
2>&1; echo $?
> exits with 0
> /usr/local/hadoop/bin/hadoop jar /usr/local/hadoop/hadoop-0.18.1-examples.jar pi 2>&1;
echo $?
> exits with 255
> /usr/local/hadoop/bin/hadoop jar /usr/local/hadoop/hadoop-0.18.1-examples.jar  2>&1;
echo $?
> exits with 0 
> This seems to be expected behavior.  However, running:
> /usr/local/hadoop/bin/hadoop jar /usr/local/hadoop/hadoop-0.18.1-examples.jar pi 10 badparam
2>&1; echo $?
> java.lang.NumberFormatException: For input string: "badparam"
>         at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
>         at java.lang.Long.parseLong(Long.java:403)
>         at java.lang.Long.parseLong(Long.java:461)
>         at org.apache.hadoop.examples.PiEstimator.run(PiEstimator.java:241)
>         at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
>         at org.apache.hadoop.examples.PiEstimator.main(PiEstimator.java:252)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>         at java.lang.reflect.Method.invoke(Method.java:597)
>         at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
>         at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
>         at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:53)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>         at java.lang.reflect.Method.invoke(Method.java:597)
>         at org.apache.hadoop.util.RunJar.main(RunJar.java:155)
>         at org.apache.hadoop.mapred.JobShell.run(JobShell.java:54)
>         at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
>         at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
>         at org.apache.hadoop.mapred.JobShell.main(JobShell.java:68)
> exits with 0.
> In my opinion, if a jar throws an exception that kills the program being run, and the
developer doesn't catch the exception and do a sane exit with a exit code, hadoop should at
least exit with a non-zero exit code.
> As another example, while running a main class that exits with an exit code of 201, Hadoop
will preserve the correct exit code:
>     public static void main(String[] args) throws Exception {
>     System.exit(201);
>   }
> But when deliberately creating a null pointer exception, Hadoop exits with 0.
>   public static void main(String[] args) throws Exception {
> 	Object o = null;
> 	o.toString();
>     System.exit(201);
>   }
> This behaviour makes it very difficult, if not impossible, to use Hadoop programatically
with tools such as HOD or non-Java data processing frameworks, since if a jar crashes with
an unhandled exception, Hadoop doesn't inform the calling program in a well-bahaved way (polling
stderr for output is not a very good way to detect application failure).     
> I'm not a Java programmer, so I don't know what the best code to signal failure would
be.
> Please let me know what other information I can include about my setup
> Thanks.

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