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From "ChiaHung Lin (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Edited] (HAMA-378) Lost connection to BSP Master [host/ip:port]. Retrying...
Date Wed, 27 Apr 2011 02:39:03 GMT

    [ https://issues.apache.org/jira/browse/HAMA-378?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13025568#comment-13025568
] 

ChiaHung Lin edited comment on HAMA-378 at 4/27/11 2:38 AM:
------------------------------------------------------------

The groom server has path referred to the jar file copied it. And the jar file exists on the
groom server, but the file to be unpacked in the path is not a correct one. 

>From what has been discovered, it looks like when executing findContainingJar() in BSPJob,
my_class.getClassLoader() would be different from what has been proposed in RunJar, in which
the context class loader is set to URLClassLoader. Also, the jar file in command e.g. `hama
jar path/to/eaxmple.jar` is added to classpath (if what perceived is correct). But in the
findContainingJar function, the context loader is not the one proposed i.e. URLClassLoader;
therefore, url.getProtocol() only returns `file' instead of `jar', resulting the execution
of findContaingJar function returns null. Thus, bsp.jar is not set in configuration. 

This is just what is discovered, but it might be a red herring and a further investigation
may be required. 




      was (Author: chl501):
    The jar file exists on the groom server, but the file to be unpacked in the path is not
a correct one. 

>From what has been discovered, it looks like when executing findContainingJar() in BSPJob,
my_class.getClassLoader() would be different from what has been proposed in RunJar, in which
the context class loader is set to URLClassLoader. Also, the jar file in command e.g. `hama
jar path/to/eaxmple.jar` is added to classpath (if what perceived is correct). But in the
findContainingJar function, the context loader is not the one proposed i.e. URLClassLoader;
therefore, url.getProtocol() only returns `file' instead of `jar', resulting the execution
of findContaingJar function returns null. Thus, bsp.jar is not set in configuration. 

This is just what is discovered, but it might be a red herring and a further investigation
may be required. 



  
> Lost connection to BSP Master [host/ip:port].  Retrying... 
> -----------------------------------------------------------
>
>                 Key: HAMA-378
>                 URL: https://issues.apache.org/jira/browse/HAMA-378
>             Project: Hama
>          Issue Type: Improvement
>          Components: bsp
>            Reporter: ChiaHung Lin
>            Priority: Minor
>
> When submitting a job, at the server side the GroomServer reports message
>     Lost connection to BSP Master [host/ip:port].  Retrying... java.lang.NullPointerException
> This seems because the script hama only includes jar files (such as hama-0.3.0-examples.jar)
located under basedir, the same folder as build.xml. Also, a quick check shows that when submitting
a job, the ClassLader used is sun.misc.Launcher$AppClassLoader, instead of java.net.URLClassLoader.
This might not be the root cause, but a further investigation may be required. 

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