[jira] [Updated] (ACCUMULO-3745) deadlock in SourceSwitchingIterator

["Josh Elser (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ACCUMULO-3745?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Josh Elser updated ACCUMULO-3745:
---------------------------------
    Assignee: Keith Turner

> deadlock in SourceSwitchingIterator
> -----------------------------------
>
>                 Key: ACCUMULO-3745
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3745
>             Project: Accumulo
>          Issue Type: Bug
>          Components: tserver
>    Affects Versions: 1.5.0, 1.5.1, 1.5.2, 1.6.0, 1.6.1, 1.6.2
>         Environment: Large production cluster, with complex iterator trees.
>            Reporter: Eric Newton
>            Assignee: Keith Turner
>            Priority: Blocker
>             Fix For: 1.5.3, 1.7.0, 1.6.3
>
>         Attachments: ACCUMULO-3745-1.patch, ACCUMULO-3745-2.patch, ACCUMULO-3745-3.patch
>
>          Time Spent: 1h 20m
>  Remaining Estimate: 0h
>
> Details come from an offline cluster, so it's difficult to reproduce the exact details.  A very complex iterator was running over tablet. "deepCopy" may have been called a couple dozen times, which may have contributed to the problem.
> Relevant facts:
> A scan and a minor compaction created a deadlock which was detected by the java runtime.
> {noformat}
> "Query... ":
>   waiting to lock monitor 0x1234 (object 0x1234, a java.util.Collections$SynchronizedRandomAccessList), 
>   which is held by "minor compactor 1"
> "minor compactor 1":
>  waiting to lock monitor 0x9876 (object 0x9876, a org.apache.accumulo.core.iterators.system.SourceSwitchingIterator), 
>  which is held by "Query..."
> {noformat}
> Java stacks:
> {noformat}
> "Query..."
>   at java.util.Collections@SynchronizedCollection.add(Collections.java:1636)
>   - waiting to lock <0x1234> (a java.util.Collections$SynchronizedRandomAccessList)
>   at org.apache.accumulo.core.iterators.system.SourceSwitchingIterator.<init>(SourceSwitchingIterator.java:72)
>  at org.apache.accumulo.core.iterators.system.SourceSwitchingIterator.deepCopy(SourceSwitchingIterator:85)
>  - locked <0x9876> (a org.apache.accumulo.core.iterators.system.SourceSwitchingIterator)
>   ... PartialMutationSkippingIterator.deepCopy(InMememoryMap.java:113)
>  ... InMemoryMap#MemoryIterator.deepCopy(InnMemoryMap.java:623)
>  ...
> {noformat}
> and:
> {noformat}
> "minor compactor 1":
>  at org.apache.accumulo.core.iterators.system.SourceSwitchingIterarot._switchNow(SourceSwitchingIterator:171)
>  - waiting to lock <0x9876> (a org.apache.accumulo.core.iterators.system.SourceSwitchingIterator)
>  at org.apache.accumulo.iterators.system.SourceSwitchingIterator.switchNow(SourceSwitchingIterator.java:184)
>  locked <0x1234> (a java.util.Collections#SynhronizedRandomAccessList)
>  at org.apache.accumulo.tserver.InMemoryMap$MemoryIterator.switchNow(InMemoryMap.java:647)
>  ...
> {noformat}



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