[jira] [Assigned] (FLINK-3271) Using webhdfs in a flink topology throws classnotfound exception

["Abhishek Agarwal (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-3271?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Abhishek Agarwal reassigned FLINK-3271:
---------------------------------------

    Assignee: Abhishek Agarwal

> Using webhdfs in a flink topology throws classnotfound exception
> ----------------------------------------------------------------
>
>                 Key: FLINK-3271
>                 URL: https://issues.apache.org/jira/browse/FLINK-3271
>             Project: Flink
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 0.10.1
>            Reporter: Abhishek Agarwal
>            Assignee: Abhishek Agarwal
>
> I was just trying to run a storm topology on flink using flink-storm. I got this exception - 
> {noformat}
> Caused by: java.lang.NoClassDefFoundError: org/mortbay/util/ajax/JSON
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.jsonParse(WebHdfsFileSystem.java:325)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$FsPathResponseRunner.getResponse(WebHdfsFileSystem.java:727)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.runWithRetry(WebHdfsFileSystem.java:610)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.access$100(WebHdfsFileSystem.java:458)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner$1.run(WebHdfsFileSystem.java:487)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at javax.security.auth.Subject.doAs(Subject.java:422)
> 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem$AbstractRunner.run(WebHdfsFileSystem.java:483)
> 	at org.apache.hadoop.hdfs.web.WebHdfsFileSystem.listStatus(WebHdfsFileSystem.java:1277)
> {noformat}
> My topology list some files on hdfs using webhdfs API. org.mortbay.util.ajax.JSON was included in the application uber jar. I noticed that flink loads the application jar in a child classloader. This is what most likely happened - 
> 1. WebHdfsFileSystem class was loaded through parent class loader since it is included in flink-dist.jar.
> 2. WebHdfsFileSystem has reference to the org.mortbay.util.ajax.JSON but since it is loaded through parent class loader, WebHdfsFileSystem can't read a class in child class loader. 
> Ideally all the referenced classes should be available in the distribution jar so that these sort of issues may not occur. 



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