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https://issues.apache.org/jira/browse/FLINK-3271?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15126432#comment-15126432
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ASF GitHub Bot commented on FLINK-3271:
---------------------------------------
Github user abhishekagarwal87 commented on the pull request:
https://github.com/apache/flink/pull/1543#issuecomment-178038559
Hi @StephanEwen
how does separating out hadoop classes solve the classloader problem? Since
even if the jars are different, they will be loaded in parent classloader and
application jar is in child classloader.
> 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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