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https://issues.apache.org/jira/browse/MAPREDUCE-5957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14063151#comment-14063151
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Sangjin Lee commented on MAPREDUCE-5957:
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Thanks for the feedback Jason.
I do like the idea of providing a convenience method that wraps the logic of
setting and unsetting the classloader around code. I think it will lead to
easier and more obvious handling of this. I'll update the patch to do that
(lambda would have been very nice btw).
Also, a good catch about the committer event handler thread creation. I'll also
handle that scenario.
I think the latest patch should cover at least all these known cases, except
for one. It's the composite service's serviceInit() and serviceStart(). In case
of the speculator, it's added as a service to the parent composite service. As
such, super.serviceInit() and super.serviceStart() will invoke its
serviceInit() and serviceStart(). If it loads classes via configuration
classloader or TCCL, it will break.
Note that normal classloading will still work. For that matter, if any of these
classes loads other classes in the normal way, that still works fine.
> AM throws ClassNotFoundException with job classloader enabled if custom
> output format/committer is used
> -------------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5957
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5957
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 2.4.0
> Reporter: Sangjin Lee
> Assignee: Sangjin Lee
> Attachments: MAPREDUCE-5957.patch, MAPREDUCE-5957.patch,
> MAPREDUCE-5957.patch
>
>
> With the job classloader enabled, the MR AM throws ClassNotFoundException if
> a custom output format class is specified.
> {noformat}
> org.apache.hadoop.yarn.exceptions.YarnRuntimeException:
> java.lang.RuntimeException: java.lang.ClassNotFoundException: Class
> com.foo.test.TestOutputFormat not found
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.createOutputCommitter(MRAppMaster.java:473)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.serviceInit(MRAppMaster.java:374)
> at
> org.apache.hadoop.service.AbstractService.init(AbstractService.java:163)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster$1.run(MRAppMaster.java:1459)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:415)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.initAndStartAppMaster(MRAppMaster.java:1456)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.main(MRAppMaster.java:1389)
> Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException:
> Class com.foo.test.TestOutputFormat not found
> at
> org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1895)
> at
> org.apache.hadoop.mapreduce.task.JobContextImpl.getOutputFormatClass(JobContextImpl.java:222)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.createOutputCommitter(MRAppMaster.java:469)
> ... 8 more
> Caused by: java.lang.ClassNotFoundException: Class
> com.foo.test.TestOutputFormat not found
> at
> org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:1801)
> at
> org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1893)
> ... 10 more
> {noformat}
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