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https://issues.apache.org/jira/browse/HBASE-17379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15783205#comment-15783205
]
stack commented on HBASE-17379:
-------------------------------
Thanks [~eshcar] (and [~anastas]). I was worried that applying blind
synchronizations, while it might 'fix' the problem, we'd just be causing new
issues instead.
Loads of work has been done to undo synchronizations in read and write. Lets be
careful adding them back.
> Lack of synchronization in CompactionPipeline#getScanners()
> -----------------------------------------------------------
>
> Key: HBASE-17379
> URL: https://issues.apache.org/jira/browse/HBASE-17379
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.0.0
> Reporter: Ted Yu
> Assignee: Ted Yu
> Attachments: 17379.v1.txt, 17379.v2.txt, 17379.v3.txt, 17379.v4.txt,
> 17379.v5.txt
>
>
> From
> https://builds.apache.org/job/PreCommit-HBASE-Build/5053/testReport/org.apache.hadoop.hbase.regionserver/TestHRegionWithInMemoryFlush/testWritesWhileGetting/
> :
> {code}
> java.io.IOException: java.util.ConcurrentModificationException
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.handleException(HRegion.java:5886)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.initializeScanners(HRegion.java:5856)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.<init>(HRegion.java:5819)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.instantiateRegionScanner(HRegion.java:2786)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:2766)
> at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:7036)
> at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:7015)
> at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:6994)
> at
> org.apache.hadoop.hbase.regionserver.TestHRegion.testWritesWhileGetting(TestHRegion.java:4141)
> 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:498)
> at
> org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
> at
> org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
> at
> org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
> at
> org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
> at
> org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
> at
> org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
> at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
> at org.junit.rules.RunRules.evaluate(RunRules.java:20)
> at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
> at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
> at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
> at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
> at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
> at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
> at
> org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
> at
> org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: java.util.ConcurrentModificationException: null
> at
> java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
> at java.util.LinkedList$ListItr.next(LinkedList.java:888)
> at
> org.apache.hadoop.hbase.regionserver.CompactionPipeline.getScanners(CompactionPipeline.java:220)
> at
> org.apache.hadoop.hbase.regionserver.CompactingMemStore.getScanners(CompactingMemStore.java:298)
> at
> org.apache.hadoop.hbase.regionserver.HStore.getScanners(HStore.java:1154)
> at org.apache.hadoop.hbase.regionserver.Store.getScanners(Store.java:97)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.getScannersNoCompaction(StoreScanner.java:353)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.<init>(StoreScanner.java:210)
> at
> org.apache.hadoop.hbase.regionserver.HStore.createScanner(HStore.java:1892)
> at
> org.apache.hadoop.hbase.regionserver.HStore.getScanner(HStore.java:1880)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.initializeScanners(HRegion.java:5842)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.<init>(HRegion.java:5819)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.instantiateRegionScanner(HRegion.java:2786)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:2766)
> at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:7036)
> {code}
> The cause is in CompactionPipeline#getScanners() where there is no
> synchronization around iterating pipeline.
> The code causing ConcurrentModificationException:
> {code}
> for (Segment segment : this.pipeline) {
> {code}
> was introduced by HBASE-17081
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