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https://issues.apache.org/jira/browse/HBASE-17501?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15883108#comment-15883108
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stack commented on HBASE-17501:
-------------------------------
Thank you for the patch [~lumost]. It looks good. Is there a utility class
adjacent that you could move this into....
388 try {
389 // attempt to seek inside of current blockReader
390 istream.seek(seekPoint);
391 } catch (NullPointerException | IOException e) {
392 // if the seek throws a null pointer exception or IOException
attempt to seek on an alternative copy of the data
393 // this can occur if the blockReader on the DFSInputStream is null
394 istream.seekToNewSource(seekPoint);
395 }
... since it repeats.
I like the reseek when NPE. You think we should reseek on an IOE too?
Thanks boss.
> NullPointerException after Datanodes Decommissioned and Terminated
> ------------------------------------------------------------------
>
> Key: HBASE-17501
> URL: https://issues.apache.org/jira/browse/HBASE-17501
> Project: HBase
> Issue Type: Bug
> Affects Versions: 1.2.0
> Environment: CentOS Derivative with a derivative of the 3.18.43
> kernel. HBase on CDH5.9.0 with some patches. HDFS CDH 5.9.0 with no patches.
> Reporter: Patrick Dignan
> Priority: Minor
> Attachments: HBASE_17501.patch
>
>
> We recently encountered an interesting NullPointerException in HDFS that
> bubbles up to HBase, and is resolved be restarting the regionserver. The
> issue was exhibited while we were replacing a set of nodes in one of our
> clusters with a new set. We did the following:
> 1. Turn off the HBase balancer
> 2. Gracefully move the regions off the nodes we’re shutting off using a tool
> we wrote to do so
> 3. Decommission the datanodes using the HDFS exclude hosts file and hdfs
> dfsadmin -refreshNodes
> 4. Wait for the datanodes to decommission fully
> 5. Terminate the VMs the instances are running inside.
> A few notes. We did not shutdown the datanode processes, and the nodes were
> therefore not marked as dead by the namenode. We simply terminated the
> datanode VM (in this case an AWS instance). The nodes were marked as
> decommissioned. We are running our clusters with DNS, and when we terminate
> VMs, the associated CName is removed and no longer resolves. The errors do
> not seem to resolve without a restart.
> After we did this, the remaining regionservers started throwing
> NullPointerExceptions with the following stack trace:
> 2017-01-19 23:09:05,638 DEBUG org.apache.hadoop.hbase.ipc.RpcServer:
> RpcServer.RW.fifo.Q.read.handler=80,queue=14,port=60020: callId: 1727723891
> service: ClientService methodName: Scan size: 216 connection:
> 172.16.36.128:31538
> java.io.IOException
> at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2214)
> at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:123)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:204)
> at
> org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:183)
> Caused by: java.lang.NullPointerException
> at org.apache.hadoop.hdfs.DFSInputStream.seek(DFSInputStream.java:1564)
> at org.apache.hadoop.fs.FSDataInputStream.seek(FSDataInputStream.java:62)
> at
> org.apache.hadoop.hbase.io.hfile.HFileBlock$AbstractFSReader.readAtOffset(HFileBlock.java:1434)
> at
> org.apache.hadoop.hbase.io.hfile.HFileBlock$FSReaderImpl.readBlockDataInternal(HFileBlock.java:1682)
> at
> org.apache.hadoop.hbase.io.hfile.HFileBlock$FSReaderImpl.readBlockData(HFileBlock.java:1542)
> at
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2.readBlock(HFileReaderV2.java:445)
> at
> org.apache.hadoop.hbase.io.hfile.HFileBlockIndex$BlockIndexReader.loadDataBlockWithScanInfo(HFileBlockIndex.java:266)
> at
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2$AbstractScannerV2.seekTo(HFileReaderV2.java:642)
> at
> org.apache.hadoop.hbase.io.hfile.HFileReaderV2$AbstractScannerV2.seekTo(HFileReaderV2.java:592)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seekAtOrAfter(StoreFileScanner.java:294)
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.seek(StoreFileScanner.java:199)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.seekScanners(StoreScanner.java:343)
> at
> org.apache.hadoop.hbase.regionserver.StoreScanner.<init>(StoreScanner.java:198)
> at
> org.apache.hadoop.hbase.regionserver.HStore.createScanner(HStore.java:2106)
> at
> org.apache.hadoop.hbase.regionserver.HStore.getScanner(HStore.java:2096)
> at
> org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.<init>(HRegion.java:5544)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.instantiateRegionScanner(HRegion.java:2569)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:2555)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.getScanner(HRegion.java:2536)
> at
> org.apache.hadoop.hbase.regionserver.RSRpcServices.scan(RSRpcServices.java:2405)
> at
> org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:33738)
> at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2170)
> ... 3 more
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