[HDFS-15237] Get checksum of EC file failed, when some block is missing or corrupt

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Duplicate
• Affects Version/s: 3.2.1
• Component/s: ec, hdfs
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Chenyu Zheng
• Created: 24/Mar/20 09:35
• Updated: 10/Nov/20 21:11
• Resolved: 04/Nov/20 05:42

Description

When we distcp from an ec directory to another one, I found some error like this.

2020-03-20 20:18:21,366 WARN [main] org.apache.hadoop.hdfs.FileChecksumHelper: src=/EC/6-3/****/000325_0, datanodes[6]=DatanodeInfoWithStorage[10.200.128.40:9866,DS-65ac4407-9d33-4c59-8f72-dd1d80d26d9f,DISK]2020-03-20 20:18:21,366 WARN [main] org.apache.hadoop.hdfs.FileChecksumHelper: src=/EC/6-3/****/000325_0, datanodes[6]=DatanodeInfoWithStorage[10.200.128.40:9866,DS-65ac4407-9d33-4c59-8f72-dd1d80d26d9f,DISK]java.io.EOFException: Unexpected EOF while trying to read response from server at org.apache.hadoop.hdfs.protocolPB.PBHelperClient.vintPrefixed(PBHelperClient.java:550) at org.apache.hadoop.hdfs.FileChecksumHelper$StripedFileNonStripedChecksumComputer.tryDatanode(FileChecksumHelper.java:709) at org.apache.hadoop.hdfs.FileChecksumHelper$StripedFileNonStripedChecksumComputer.checksumBlockGroup(FileChecksumHelper.java:664) at org.apache.hadoop.hdfs.FileChecksumHelper$StripedFileNonStripedChecksumComputer.checksumBlocks(FileChecksumHelper.java:638) at org.apache.hadoop.hdfs.FileChecksumHelper$FileChecksumComputer.compute(FileChecksumHelper.java:252) at org.apache.hadoop.hdfs.DFSClient.getFileChecksumInternal(DFSClient.java:1790) at org.apache.hadoop.hdfs.DFSClient.getFileChecksumWithCombineMode(DFSClient.java:1810) at org.apache.hadoop.hdfs.DistributedFileSystem$33.doCall(DistributedFileSystem.java:1691) at org.apache.hadoop.hdfs.DistributedFileSystem$33.doCall(DistributedFileSystem.java:1688) at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81) at org.apache.hadoop.hdfs.DistributedFileSystem.getFileChecksum(DistributedFileSystem.java:1700) at org.apache.hadoop.tools.mapred.RetriableFileCopyCommand.doCopy(RetriableFileCopyCommand.java:138) at org.apache.hadoop.tools.mapred.RetriableFileCopyCommand.doExecute(RetriableFileCopyCommand.java:115) at org.apache.hadoop.tools.util.RetriableCommand.execute(RetriableCommand.java:87) at org.apache.hadoop.tools.mapred.CopyMapper.copyFileWithRetry(CopyMapper.java:259) at org.apache.hadoop.tools.mapred.CopyMapper.map(CopyMapper.java:220) at org.apache.hadoop.tools.mapred.CopyMapper.map(CopyMapper.java:48) at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146) at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:799) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:347) at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:174) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1730) at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:168)

And Then I found some error in datanode like this

2020-03-20 20:54:16,573 INFO org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient: SASL encryption trust check: localHostTrusted = false, remoteHostTrusted = false
2020-03-20 20:54:16,577 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: bd-hadoop-128050.zeus.lianjia.com:9866:DataXceiver error processing BLOCK_GROUP_CHECKSUM operation src: /10.201.1.38:33264 dst: /10.200.128.50:9866
java.lang.UnsupportedOperationException
 at java.nio.ByteBuffer.array(ByteBuffer.java:994)
 at org.apache.hadoop.hdfs.server.datanode.erasurecode.StripedBlockChecksumReconstructor.reconstruct(StripedBlockChecksumReconstructor.java:90)
 at org.apache.hadoop.hdfs.server.datanode.BlockChecksumHelper$BlockGroupNonStripedChecksumComputer.recalculateChecksum(BlockChecksumHelper.java:711)
 at org.apache.hadoop.hdfs.server.datanode.BlockChecksumHelper$BlockGroupNonStripedChecksumComputer.compute(BlockChecksumHelper.java:489)
 at org.apache.hadoop.hdfs.server.datanode.DataXceiver.blockGroupChecksum(DataXceiver.java:1047)
 at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opStripedBlockChecksum(Receiver.java:327)
 at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:119)
 at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:292)
 at java.lang.Thread.run(Thread.java:748)

The reason is that: When some block is missing or corrupt, datanode will trigger to call recalculateChecksum. But if StripedBlockChecksumReconstructor.targetBuffer is DirectByteBuffer, we couldn't use DirectByteBuffer.array(), so throw the exception. Then we could't get checksum.

Issue Links

• is duplicated by: HDFS-15643 EC: Fix checksum computation in case of native encoders
• links to: GitHub Pull Request #2306