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From "Sahil Takiar (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-15355) Concurrency issues during parallel moveFile due to HDFSUtils.setFullFileStatus
Date Mon, 05 Dec 2016 22:34:58 GMT

    [ https://issues.apache.org/jira/browse/HIVE-15355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15723583#comment-15723583
] 

Sahil Takiar commented on HIVE-15355:
-------------------------------------

Some comments:

* Is {{Collections.unmodifiableList(...)}} null safe, what happens if {{aclStatus.getEntries()}}
returns null
* Test {{HdfsUtils.HadoopStatus.getAclEntries()}} could be as simple as invoking the method,
trying the modify it, and then expecting an {{UnsupportedOperationException}}
* Tests for {{HdfsUtils.setFullFileStatus}} may be trickier, one idea is to pass in a mock
{{HadoopFileStatus}} and ensure that {{getAclEntries}} is invoked, but not {{getAclStatus().getEntries()}}

> Concurrency issues during parallel moveFile due to HDFSUtils.setFullFileStatus
> ------------------------------------------------------------------------------
>
>                 Key: HIVE-15355
>                 URL: https://issues.apache.org/jira/browse/HIVE-15355
>             Project: Hive
>          Issue Type: Bug
>    Affects Versions: 2.1.0, 2.2.0
>            Reporter: Vihang Karajgaonkar
>            Assignee: Vihang Karajgaonkar
>         Attachments: HIVE-15355.01.patch
>
>
> It is possible to run into concurrency issues during multi-threaded moveFile issued when
processing queries like {{INSERT OVERWRITE TABLE ... SELECT ..}} when there are multiple files
in the staging directory which is a subdirectory of the target directory. The issue is hard
to reproduce but following stacktrace is one such example:
> {noformat}
> INFO  : Loading data to table functional_text_gzip.alltypesaggmultifilesnopart from hdfs://localhost:20500/test-warehouse/alltypesaggmultifilesnopart_text_gzip/.hive-staging_hive_2016-12-01_19-58-21_712_8968735301422943318-1/-ext-10000
> ERROR : Failed with exception java.lang.ArrayIndexOutOfBoundsException
> org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.ArrayIndexOutOfBoundsException
>         at org.apache.hadoop.hive.ql.metadata.Hive.moveFile(Hive.java:2858)
>         at org.apache.hadoop.hive.ql.metadata.Hive.replaceFiles(Hive.java:3124)
>         at org.apache.hadoop.hive.ql.metadata.Hive.loadTable(Hive.java:1701)
>         at org.apache.hadoop.hive.ql.exec.MoveTask.execute(MoveTask.java:313)
>         at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:214)
>         at org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:100)
>         at org.apache.hadoop.hive.ql.Driver.launchTask(Driver.java:1976)
>         at org.apache.hadoop.hive.ql.Driver.execute(Driver.java:1689)
>         at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1421)
>         at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1205)
>         at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1200)
>         at org.apache.hive.service.cli.operation.SQLOperation.runQuery(SQLOperation.java:237)
>         at org.apache.hive.service.cli.operation.SQLOperation.access$300(SQLOperation.java:88)
>         at org.apache.hive.service.cli.operation.SQLOperation$3$1.run(SQLOperation.java:293)
>         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:1796)
> Getting log thread is interrupted, since query is done!
>         at org.apache.hive.service.cli.operation.SQLOperation$3.run(SQLOperation.java:306)
>         at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
>         at java.util.concurrent.FutureTask.run(FutureTask.java:262)
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>         at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.ArrayIndexOutOfBoundsException
>         at java.lang.System.arraycopy(Native Method)
>         at java.util.ArrayList.removeRange(ArrayList.java:616)
>         at java.util.ArrayList$SubList.removeRange(ArrayList.java:1021)
>         at java.util.AbstractList.clear(AbstractList.java:234)
>         at com.google.common.collect.Iterables.removeIfFromRandomAccessList(Iterables.java:213)
>         at com.google.common.collect.Iterables.removeIf(Iterables.java:184)
>         at org.apache.hadoop.hive.shims.Hadoop23Shims.removeBaseAclEntries(Hadoop23Shims.java:865)
>         at org.apache.hadoop.hive.shims.Hadoop23Shims.setFullFileStatus(Hadoop23Shims.java:757)
>         at org.apache.hadoop.hive.ql.metadata.Hive$3.call(Hive.java:2835)
>         at org.apache.hadoop.hive.ql.metadata.Hive$3.call(Hive.java:2828)
>         ... 4 more
> ERROR : FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.MoveTask
> {noformat}
> Quick online search also shows some other instances like the one mentioned in http://stackoverflow.com/questions/38900333/get-concurrentmodificationexception-in-step-2-create-intermediate-flat-hive-tab
> The issue seems to be coming from the below code :
> {code}
> if (aclEnabled) {
>       aclStatus =  sourceStatus.getAclStatus();
>       if (aclStatus != null) {
>         LOG.trace(aclStatus.toString());
>         aclEntries = aclStatus.getEntries();
>         removeBaseAclEntries(aclEntries);
>         //the ACL api's also expect the tradition user/group/other permission in the
form of ACL
>         aclEntries.add(newAclEntry(AclEntryScope.ACCESS, AclEntryType.USER, sourcePerm.getUserAction()));
>         aclEntries.add(newAclEntry(AclEntryScope.ACCESS, AclEntryType.GROUP, sourcePerm.getGroupAction()));
>         aclEntries.add(newAclEntry(AclEntryScope.ACCESS, AclEntryType.OTHER, sourcePerm.getOtherAction()));
>       }
>     }
> {code}
> removeBaseAclEntries removes objects from {{List<AclEntry> aclEntries}} When HDFSUtils.setFullFileStatus()
method is called from multiple threads like from https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/metadata/Hive.java#L2835
it is possible that multiple threads try to modify the {{List<AclEntry> aclEntries}}
leading to concurrency issues. 
> We should either move that block into a thread-safe region or call setFullFileStatus
when all the threads converge.



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