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Date: Wed, 29 Oct 2008 07:49:44 -0700 (PDT)
From: "Nigel Daley (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Updated: (HADOOP-4340) "hadoop jar" always returns exit code
 0 (success) to the shell when jar throws a fatal exception
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     [ https://issues.apache.org/jira/browse/HADOOP-4340?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nigel Daley updated HADOOP-4340:
--------------------------------

    Fix Version/s: 0.19.0
                   0.18.2

> "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
>          Components: examples, mapred
>    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
>            Assignee: Amareshwari Sriramadasu
>             Fix For: 0.18.2, 0.19.0
>
>         Attachments: patch-4340-1.txt, patch-4340.txt
>
>
> 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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