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Date: Thu, 2 Nov 2017 21:29:00 +0000 (UTC)
From: "huaxiang sun (JIRA)" <jira@apache.org>
To: dev@hbase.apache.org
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Subject: [jira] [Created] (HBASE-19163) "Maximum Lock Acquired" from region
 server's batch processing
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archived-at: Thu, 02 Nov 2017 21:29:06 -0000

huaxiang sun created HBASE-19163:
------------------------------------

             Summary: "Maximum Lock Acquired" from region server's batch processing
                 Key: HBASE-19163
                 URL: https://issues.apache.org/jira/browse/HBASE-19163
             Project: HBase
          Issue Type: Bug
          Components: regionserver
    Affects Versions: 1.2.7
            Reporter: huaxiang sun
            Assignee: huaxiang sun
            Priority: Major


In one of use cases, we found the following exception and replication is stuck.

{code}
2017-10-25 19:41:17,199 WARN  [hconnection-0x28db294f-shared--pool4-t936] client.AsyncProcess: #3, table=foo, attempt=5/5 failed=262836ops, last exception: java.io.IOException: java.io.IOException: Maximum lock count exceeded
        at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2215)
        at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:109)
        at org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:185)
        at org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:165)
Caused by: java.lang.Error: Maximum lock count exceeded
        at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.fullTryAcquireShared(ReentrantReadWriteLock.java:528)
        at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryAcquireShared(ReentrantReadWriteLock.java:488)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1327)
        at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.tryLock(ReentrantReadWriteLock.java:871)
        at org.apache.hadoop.hbase.regionserver.HRegion.getRowLock(HRegion.java:5163)
        at org.apache.hadoop.hbase.regionserver.HRegion.doMiniBatchMutation(HRegion.java:3018)
        at org.apache.hadoop.hbase.regionserver.HRegion.batchMutate(HRegion.java:2877)
        at org.apache.hadoop.hbase.regionserver.HRegion.batchMutate(HRegion.java:2819)
        at org.apache.hadoop.hbase.regionserver.RSRpcServices.doBatchOp(RSRpcServices.java:753)
        at org.apache.hadoop.hbase.regionserver.RSRpcServices.doNonAtomicRegionMutation(RSRpcServices.java:715)
        at org.apache.hadoop.hbase.regionserver.RSRpcServices.multi(RSRpcServices.java:2148)
        at org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:33656)
        at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2170)
        ... 3 more

{code}

While we are still examining the data pattern, it is sure that there are too many mutations in the batch against the same row, this exceeds the maximum 64k shared lock count and it throws an error and failed the whole batch.

There are two approaches to solve this issue.

1). Let's say there are mutations against the same row in the batch, we just need to acquire the lock once for the same row vs to acquire the lock for each mutation.
2). We catch the error and start to process whatever it gets and loop back.

With HBASE-17924, approach 1 seems easy to implement now. 
Create the jira and will post update/patch when investigation moving forward.


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