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https://issues.apache.org/jira/browse/PHOENIX-3111?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15398720#comment-15398720
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Samarth Jain commented on PHOENIX-3111:
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[~rajeshbabu] - my question is an extension to what [~jamestaylor] had. Does
the split process creates its own instance of UngroupedAggregateRegionObserver?
If yes, then wouldn't it see default values of member variables
isRegionClosing, scansReferenceCount etc? If yes, how is the whole
synchronization going to work? I *think* you are probably going to need a
singleton to track state at the region server level. See
StatisticsCollectionRunTracker as an example of how this could be done.
> Possible Deadlock/delay while building index, upsert select, delete rows at
> server
> ----------------------------------------------------------------------------------
>
> Key: PHOENIX-3111
> URL: https://issues.apache.org/jira/browse/PHOENIX-3111
> Project: Phoenix
> Issue Type: Bug
> Reporter: Sergio Peleato
> Assignee: Rajeshbabu Chintaguntla
> Priority: Critical
> Fix For: 4.8.1
>
> Attachments: PHOENIX-3111.patch
>
>
> There is a possible deadlock while building local index or running upsert
> select, delete at server. The situation might happen in this case.
> In the above queries we scan mutations from table and write back to same
> table in that case there is a chance of memstore might reach the threshold of
> blocking memstore size then RegionTooBusyException might be thrown back to
> client and queries might retry scanning.
> Let's suppose if we take a local index build index case we first scan from
> the data table and prepare index mutations and write back to same table.
> So there is chance of memstore full as well in that case we try to flush the
> region. But if the split happen in between then split might be waiting for
> write lock on the region to close and flush wait for readlock because the
> write lock in the queue until the local index build completed. Local index
> build won't complete because we are not allowed to write until there is
> flush. This might not be complete deadlock situation but the queries might
> take lot of time to complete in this cases.
> {noformat}
> "regionserver//192.168.0.53:16201-splits-1469165876186" #269 prio=5
> os_prio=31 tid=0x00007f7fb2050800 nid=0x1c033 waiting on condition
> [0x0000000139b68000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00000006ede72550> (a
> java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
> at
> java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock(ReentrantReadWriteLock.java:943)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.doClose(HRegion.java:1422)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.close(HRegion.java:1370)
> - locked <0x00000006ede69d00> (a java.lang.Object)
> at
> org.apache.hadoop.hbase.regionserver.SplitTransactionImpl.stepsBeforePONR(SplitTransactionImpl.java:394)
> at
> org.apache.hadoop.hbase.regionserver.SplitTransactionImpl.createDaughters(SplitTransactionImpl.java:278)
> at
> org.apache.hadoop.hbase.regionserver.SplitTransactionImpl.execute(SplitTransactionImpl.java:561)
> at
> org.apache.hadoop.hbase.regionserver.SplitRequest.doSplitting(SplitRequest.java:82)
> at
> org.apache.hadoop.hbase.regionserver.SplitRequest.run(SplitRequest.java:154)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> Locked ownable synchronizers:
> - <0x00000006ee132098> (a
> java.util.concurrent.ThreadPoolExecutor$Worker)
> {noformat}
> {noformat}
> "MemStoreFlusher.0" #170 prio=5 os_prio=31 tid=0x00007f7fb6842000 nid=0x19303
> waiting on condition [0x00000001388e9000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00000006ede72550> (a
> java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireShared(AbstractQueuedSynchronizer.java:967)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireShared(AbstractQueuedSynchronizer.java:1283)
> at
> java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.lock(ReentrantReadWriteLock.java:727)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.flushcache(HRegion.java:1986)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.flush(HRegion.java:1950)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:501)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:471)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher.access$800(MemStoreFlusher.java:75)
> at
> org.apache.hadoop.hbase.regionserver.MemStoreFlusher$FlushHandler.run(MemStoreFlusher.java:259)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> As a fix we need to block region splits if building index, upsert select,
> delete rows running at server.
> Thanks [~sergey.soldatov] for the help in understanding the bug and analyzing
> it. [~speleato] for finding it.
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