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https://issues.apache.org/jira/browse/HBASE-5623?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Zhihong Yu updated HBASE-5623:
------------------------------
Hadoop Flags: Reviewed
Status: Patch Available (was: Open)
Patch makes sense.
> Race condition when rolling the HLog and hlogFlush
> --------------------------------------------------
>
> Key: HBASE-5623
> URL: https://issues.apache.org/jira/browse/HBASE-5623
> Project: HBase
> Issue Type: Bug
> Components: wal
> Affects Versions: 0.94.0
> Reporter: Enis Soztutar
> Assignee: Enis Soztutar
> Attachments: HBASE-5623_v0.patch
>
>
> When doing a ycsb test with a large number of handlers
> (regionserver.handler.count=60), I get the following exceptions:
> {code}
> Caused by: org.apache.hadoop.ipc.RemoteException: java.io.IOException:
> java.lang.NullPointerException
> at
> org.apache.hadoop.io.SequenceFile$Writer.getLength(SequenceFile.java:1099)
> at
> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogWriter.getLength(SequenceFileLogWriter.java:314)
> at org.apache.hadoop.hbase.regionserver.wal.HLog.syncer(HLog.java:1291)
> at org.apache.hadoop.hbase.regionserver.wal.HLog.sync(HLog.java:1388)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.doMiniBatchPut(HRegion.java:2192)
> at org.apache.hadoop.hbase.regionserver.HRegion.put(HRegion.java:1985)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.multi(HRegionServer.java:3400)
> at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:366)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1351)
> at org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:920)
> at
> org.apache.hadoop.hbase.ipc.WritableRpcEngine$Invoker.invoke(WritableRpcEngine.java:152)
> at $Proxy1.multi(Unknown Source)
> at
> org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation$3$1.call(HConnectionManager.java:1691)
> at
> org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation$3$1.call(HConnectionManager.java:1689)
> at
> org.apache.hadoop.hbase.client.ServerCallable.withoutRetries(ServerCallable.java:214)
> {code}
> and
> {code}
> java.lang.NullPointerException
> at
> org.apache.hadoop.io.SequenceFile$Writer.checkAndWriteSync(SequenceFile.java:1026)
> at
> org.apache.hadoop.io.SequenceFile$Writer.append(SequenceFile.java:1068)
> at
> org.apache.hadoop.io.SequenceFile$Writer.append(SequenceFile.java:1035)
> at
> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogWriter.append(SequenceFileLogWriter.java:279)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog$LogSyncer.hlogFlush(HLog.java:1237)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.syncer(HLog.java:1271)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.sync(HLog.java:1391)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.doMiniBatchPut(HRegion.java:2192)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.put(HRegion.java:1985)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.multi(HRegionServer.java:3400)
> at sun.reflect.GeneratedMethodAccessor33.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:366)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1351)
> {code}
> It seems the root cause of the issue is that we open a new log writer and
> close the old one at HLog#rollWriter() holding the updateLock, but the other
> threads doing syncer() calls
> {code}
> logSyncerThread.hlogFlush(this.writer);
> {code}
> without holding the updateLock. LogSyncer only synchronizes against
> concurrent appends and flush(), but not on the passed writer, which can be
> closed already by rollWriter(). In this case, since
> SequenceFile#Writer.close() sets it's out field as null, we get the NPE.
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