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https://issues.apache.org/jira/browse/MAPREDUCE-5837?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Haohui Mai updated MAPREDUCE-5837:
----------------------------------
Resolution: Fixed
Fix Version/s: 2.5.0
Status: Resolved (was: Patch Available)
I've committed the patch to trunk and branch-2. Thanks Chris for the review.
> MRAppMaster fails when checking on uber mode
> --------------------------------------------
>
> Key: MAPREDUCE-5837
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5837
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Haohui Mai
> Assignee: Haohui Mai
> Priority: Critical
> Fix For: 2.5.0
>
> Attachments: MAPREDUCE-5837.000.patch
>
>
> When the MRAppMaster determines whether the job should run in the uber mode,
> it call {{Class.forName()}} to check whether the class is derived from
> {{ChainMapper}}:
> {code}
> try {
> String mapClassName = conf.get(MRJobConfig.MAP_CLASS_ATTR);
> if (mapClassName != null) {
> Class<?> mapClass = Class.forName(mapClassName);
> if (ChainMapper.class.isAssignableFrom(mapClass))
> isChainJob = true;
> }
> } catch (ClassNotFoundException cnfe) {
> // don't care; assume it's not derived from ChainMapper
> }
> {code}
> The problem here is that {{Class.forName()}} can also throw
> {{NoClassDefError}}. It happens when the additional dependent jar is
> unavailable to the MRAppMaster. For example, the MRAppMaster complains about
> a MR job on Scala:
> {noformat}
> 2014-04-15 11:52:55,877 FATAL [main]
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster: Error starting MRAppMaster
> java.lang.NoClassDefFoundError: scala/Function1
> at java.lang.Class.forName0(Native Method)
> at java.lang.Class.forName(Class.java:190)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.isChainJob(JobImpl.java:1282)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.makeUberDecision(JobImpl.java:1224)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.access$3700(JobImpl.java:136)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl$InitTransition.transition(JobImpl.java:1425)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl$InitTransition.transition(JobImpl.java:1363)
> at
> org.apache.hadoop.yarn.state.StateMachineFactory$MultipleInternalArc.doTransition(StateMachineFactory.java:385)
> at
> org.apache.hadoop.yarn.state.StateMachineFactory.doTransition(StateMachineFactory.java:302)
> at
> org.apache.hadoop.yarn.state.StateMachineFactory.access$300(StateMachineFactory.java:46)
> at
> org.apache.hadoop.yarn.state.StateMachineFactory$InternalStateMachine.doTransition(StateMachineFactory.java:448)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.handle(JobImpl.java:976)
> at
> org.apache.hadoop.mapreduce.v2.app.job.impl.JobImpl.handle(JobImpl.java:135)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster$JobEventDispatcher.handle(MRAppMaster.java:1263)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.serviceStart(MRAppMaster.java:1063)
> at
> org.apache.hadoop.service.AbstractService.start(AbstractService.java:193)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster$1.run(MRAppMaster.java:1480)
> 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:1606)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.initAndStartAppMaster(MRAppMaster.java:1476)
> at
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster.main(MRAppMaster.java:1409)
> Caused by: java.lang.ClassNotFoundException: scala.Function1
> at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
> at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
> ... 22 more
> {noformat}
>
> The proposed fix is to catch {{NoClassDefError}} at the corresponding places.
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