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From "Robert Yokota (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16270) When using region replicas, get thousands of occurrences of UnexpectedStateException: Current snapshot id is -1
Date Sat, 30 Jul 2016 07:52:20 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16270?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15400525#comment-15400525

Robert Yokota commented on HBASE-16270:

It appears that this.snapshotId is set to -1 at the end of clearSnapshot().  So one way I
could see the above error happening is if two threads are concurrently calling HStore.updateStoreFiles.
 In HStore.updateStoreFiles there is write lock that is obtained.  The second thread will
wait for the lock, and when it obtains the lock it will call clearSnapshot() after the first
thread has already called it.  Since the snapshot has already been cleared (this.snapshotId
set to -1), the second call to clearSnapshot should just return, instead of throwing UnexpectedStateException.

> When using region replicas, get thousands of occurrences of UnexpectedStateException:
Current snapshot id is -1
> ---------------------------------------------------------------------------------------------------------------
>                 Key: HBASE-16270
>                 URL: https://issues.apache.org/jira/browse/HBASE-16270
>             Project: HBase
>          Issue Type: Bug
>          Components: Replication
>    Affects Versions: 1.1.2
>            Reporter: Robert Yokota
>         Attachments: HBASE-16270-branch-1.2.patch, HBASE-16270-master.patch
> We have an HBase (1.1.2) production cluster with 58 region servers and a staging cluster
with 6 region servers.
> For both clusters, we enabled region replicas with the following settings:
> hbase.regionserver.storefile.refresh.period = 0
> hbase.region.replica.replication.enabled = true
> hbase.region.replica.replication.memstore.enabled = true
> hbase.master.hfilecleaner.ttl = 3600000
> hbase.master.loadbalancer.class = org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer
> hbase.meta.replica.count = 3
> hbase.regionserver.meta.storefile.refresh.period = 30000
> hbase.region.replica.wait.for.primary.flush = true
> hbase.region.replica.storefile.refresh.memstore.multiplier = 4
> We then altered our HBase tables to have REGION_REPLICATION => 2
> Both clusters got into a state where a few region servers were spewing the following
error below in the HBase logs.  In one instance the error occurred over 70K times.  At this
time, these region servers would see 10x write traffic (the hadoop.HBase.RegionServer.Server.writeRequestCount
metric) and in some instances would crash.
> At the same time, we would see secondary regions move and then go into the "reads are
disabled" state for extended periods.  
> It appears there is a race condition where the DefaultMemStore::clearSnapshot method
might be called more than once in succession. The first call would set snapshotId to -1, but
the second call would throw an exception.  It seems the second call should just return if
the snapshotId is already -1, rather than throwing an exception.
> Thu Jul 21 08:38:50 UTC 2016, RpcRetryingCaller{globalStartTime=1469090201543, pause=100,
retries=35}, org.apache.hadoop.hbase.regionserver.UnexpectedStateException: org.apache.hadoop.hbase.regionserver.UnexpectedStateException:
Current snapshot id is -1,passed 1469085004304
>         at org.apache.hadoop.hbase.regionserver.DefaultMemStore.clearSnapshot(DefaultMemStore.java:187)
>         at org.apache.hadoop.hbase.regionserver.HStore.updateStorefiles(HStore.java:1054)
>         at org.apache.hadoop.hbase.regionserver.HStore.access$500(HStore.java:128)
>         at org.apache.hadoop.hbase.regionserver.HStore$StoreFlusherImpl.replayFlush(HStore.java:2270)
>         at org.apache.hadoop.hbase.regionserver.HRegion.replayFlushInStores(HRegion.java:4487)
>         at org.apache.hadoop.hbase.regionserver.HRegion.replayWALFlushCommitMarker(HRegion.java:4388)
>         at org.apache.hadoop.hbase.regionserver.HRegion.replayWALFlushMarker(HRegion.java:4191)
>         at org.apache.hadoop.hbase.regionserver.RSRpcServices.doReplayBatchOp(RSRpcServices.java:776)
>         at org.apache.hadoop.hbase.regionserver.RSRpcServices.replay(RSRpcServices.java:1655)
>         at org.apache.hadoop.hbase.protobuf.generated.AdminProtos$AdminService$2.callBlockingMethod(AdminProtos.java:22255)
>         at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2114)
>         at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:101)
>         at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:130)
>         at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:107)
>         at java.lang.Thread.run(Thread.java:745)

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