[jira] [Commented] (MAPREDUCE-6139) ConcurrentModificationException in ContainerLogAppender

["Gera Shegalov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6139?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14197178#comment-14197178 ] 

Gera Shegalov commented on MAPREDUCE-6139:
------------------------------------------

Hi [~kamrul], thanks for reporting the issue.

This occurs when there mapreduce.task.userlog.limit.kb > 0. I recommend not to use the original log limit implementation as it has other serious problems such as the potential to lose the valuable diagnostic information in the tail and a long delay until one can see the log to begin with. MAPREDUCE-5672 provided an alternative based on RollingFileAppender that does not have these problems which I recommend to start using.

Coming back to the problem in this scenario. One of the pending events in the Queue generated a new warn LogEvent via Token.toString and modified the tail queue while the iterator is still in progress in the {{close}} stack frame. I would fix this as follows: 
introduce instance boolean variable {{closed}} and set it to {{true}} immediately when {{close}} is invoked. Then we can make CLA's {{append}} a nop when {{closed}} is {{true}}.

> ConcurrentModificationException in ContainerLogAppender
> -------------------------------------------------------
>
>                 Key: MAPREDUCE-6139
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6139
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Mohammad Kamrul Islam
>            Assignee: Mohammad Kamrul Islam
>            Priority: Critical
>         Attachments: ContainerLogAppender.java
>
>
> Context:
> * Hadoop-2.3.0
> * Using Oozie 4.0.1
> * Pig version 0.11.x
> The job is submitted by Oozie to launch Pig script.
> The following exception traces were found on MR task log:
> In syslog:
> {noformat}
> 2014-10-24 20:37:29,317 WARN [Thread-5] org.apache.hadoop.util.ShutdownHookManager: ShutdownHook '' failed, java.util.ConcurrentModificationException
> java.util.ConcurrentModificationException
> 	at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
> 	at java.util.LinkedList$ListItr.next(LinkedList.java:888)
> 	at org.apache.hadoop.yarn.ContainerLogAppender.close(ContainerLogAppender.java:94)
> 	at org.apache.log4j.helpers.AppenderAttachableImpl.removeAllAppenders(AppenderAttachableImpl.java:141)
> 	at org.apache.log4j.Category.removeAllAppenders(Category.java:891)
> 	at org.apache.log4j.Hierarchy.shutdown(Hierarchy.java:471)
> 	at org.apache.log4j.LogManager.shutdown(LogManager.java:267)
> 	at org.apache.hadoop.mapred.TaskLog.syncLogsShutdown(TaskLog.java:286)
> 	at org.apache.hadoop.mapred.TaskLog$2.run(TaskLog.java:339)
> 	at org.apache.hadoop.util.ShutdownHookManager$1.run(ShutdownHookManager.java:54)
> 2014-10-24 20:37:29,395 INFO [main] org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Stopping MapTask metrics system...
> {noformat}
> in stderr:
> {noformat}
> java.util.ConcurrentModificationException
> 	at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
> 	at java.util.LinkedList$ListItr.next(LinkedList.java:888)
> 	at org.apache.hadoop.yarn.ContainerLogAppender.close(ContainerLogAppender.java:94)
> 	at org.apache.log4j.helpers.AppenderAttachableImpl.removeAllAppenders(AppenderAttachableImpl.java:141)
> 	at org.apache.log4j.Category.removeAllAppenders(Category.java:891)
> 	at org.apache.log4j.PropertyConfigurator.parseCategory(PropertyConfigurator.java:759)
> 	at org.apache.log4j.PropertyConfigurator.configureRootCategory(PropertyConfigurator.java:648)
> 	at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:514)
> 	at org.apache.log4j.PropertyConfigurator.configure(PropertyConfigurator.java:440)
> 	at org.apache.pig.Main.configureLog4J(Main.java:740)
> 	at org.apache.pig.Main.run(Main.java:384)
> 	at org.apache.pig.PigRunner.run(PigRunner.java:49)
> 	at org.apache.oozie.action.hadoop.PigMain.runPigJob(PigMain.java:283)
> 	at org.apache.oozie.action.hadoop.PigMain.run(PigMain.java:223)
> 	at org.apache.oozie.action.hadoop.LauncherMain.run(LauncherMain.java:37)
> 	at org.apache.oozie.action.hadoop.PigMain.main(PigMain.java:76)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> 	at java.lang.reflect.Method.invoke(Method.java:483)
> 	at org.apache.oozie.action.hadoop.LauncherMapper.map(LauncherMapper.java:226)
> 	at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:54)
> 	at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:430)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:342)
> 	at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:167)
> 	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:1548)
> 	at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)
> {noformat}



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