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From "Zhao Yi Ming (Jira)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-14768) In some cases, erasure blocks are corruption when they are reconstruct.
Date Wed, 11 Sep 2019 14:20:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-14768?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16927610#comment-16927610
] 

Zhao Yi Ming commented on HDFS-14768:
-------------------------------------

[~gjhkael] I tried the following code(which you said can stabilize reproduce the problem),
but I can always hit the DN can not decommissioned successfully, the LOG as following. Anything
I missed? Can you help? Thanks!

!image-2019-09-11-22-18-36-154.png!

 
{code:java}
// code placeholder
public void testFileDecommission() throws Exception {
		LOG.info("Starting test testFileDecommission");
		final Path ecFile = new Path(ecDir, "testFileDecommission");
		int writeBytes = cellSize * dataBlocks;
		writeStripedFile(dfs, ecFile, writeBytes);
		Assert.assertEquals(0, bm.numOfUnderReplicatedBlocks());
		FileChecksum fileChecksum1 = dfs.getFileChecksum(ecFile, writeBytes);


		LocatedBlocks locatedBlocks = StripedFileTestUtil.getLocatedBlocks(ecFile, dfs);


		LocatedBlock lb = dfs.getClient().getLocatedBlocks(ecFile.toString(), 0).get(0);
		DatanodeInfo[] dnLocs = lb.getLocations();


		LocatedStripedBlock lastBlock = (LocatedStripedBlock) locatedBlocks.getLastLocatedBlock();


		DatanodeInfo[] storageInfos = lastBlock.getLocations();


		//
		DatanodeDescriptor datanodeDescriptor = cluster.getNameNode().getNamesystem().getBlockManager()
				.getDatanodeManager().getDatanode(storageInfos[6].getDatanodeUuid());
		for (int i = 0; i < 100; i++) {
			datanodeDescriptor.incrementPendingReplicationWithoutTargets();
		}
		assertEquals(dataBlocks + parityBlocks, dnLocs.length);
		int[] decommNodeIndex = { 3, 4 };


		final List<DatanodeInfo> decommisionNodes = new ArrayList<DatanodeInfo>();
		// add the node which will be decommissioning
		decommisionNodes.add(dnLocs[decommNodeIndex[0]]);
		decommisionNodes.add(dnLocs[decommNodeIndex[1]]);
		decommissionNode(0, decommisionNodes, AdminStates.DECOMMISSIONED);


		assertEquals(decommisionNodes.size(), fsn.getNumDecomLiveDataNodes());


		// assertNull(checkFile(dfs, ecFile, 9, decommisionNodes, numDNs));


		// Ensure decommissioned datanode is not automatically shutdown
		DFSClient client = getDfsClient(cluster.getNameNode(0), conf);
		assertEquals("All datanodes must be alive", numDNs, client.datanodeReport(DatanodeReportType.LIVE).length);


		FileChecksum fileChecksum2 = dfs.getFileChecksum(ecFile, writeBytes);
		Assert.assertTrue("Checksum mismatches!", fileChecksum1.equals(fileChecksum2));


		StripedFileTestUtil.checkData(dfs, ecFile, writeBytes, decommisionNodes, null, blockGroupSize);
	}
{code}
 

 

> In some cases, erasure blocks are corruption  when they are reconstruct.
> ------------------------------------------------------------------------
>
>                 Key: HDFS-14768
>                 URL: https://issues.apache.org/jira/browse/HDFS-14768
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode, erasure-coding, hdfs, namenode
>    Affects Versions: 3.0.2
>            Reporter: guojh
>            Assignee: guojh
>            Priority: Major
>              Labels: patch
>             Fix For: 3.3.0
>
>         Attachments: HDFS-14768.000.patch, image-2019-09-11-22-18-36-154.png
>
>
> Policy is RS-6-3-1024K, version is hadoop 3.0.2;
> We suppose a file's block Index is [0,1,2,3,4,5,6,7,8], And decommission index[3,4],
increase the index 6 datanode's
> pendingReplicationWithoutTargets  that make it large than replicationStreamsHardLimit(we
set 14). Then, After the method chooseSourceDatanodes of BlockMananger, the liveBlockIndices
is [0,1,2,3,4,5,7,8], Block Counter is, Live:7, Decommission:2. 
> In method scheduleReconstruction of BlockManager, the additionalReplRequired is 9 - 7
= 2. After Namenode choose two target Datanode, will assign a erasureCode task to target datanode.
> When datanode get the task will build  targetIndices from liveBlockIndices and target
length. the code is blow.
> {code:java}
> // code placeholder
> targetIndices = new short[targets.length];
> private void initTargetIndices() { 
>   BitSet bitset = reconstructor.getLiveBitSet();
>   int m = 0; hasValidTargets = false; 
>   for (int i = 0; i < dataBlkNum + parityBlkNum; i++) {  
>     if (!bitset.get) {    
>       if (reconstructor.getBlockLen > 0) {
>        if (m < targets.length) {
>          targetIndices[m++] = (short)i;
>          hasValidTargets = true;
>         }
>       }
>     }
>  }
> {code}
> targetIndices[0]=6, and targetIndices[1] is aways 0 from initial value.
> The StripedReader is  aways create reader from first 6 index block, and is [0,1,2,3,4,5]
> Use the index [0,1,2,3,4,5] to build target index[6,0] will trigger the isal bug. the
block index6's data is corruption(all data is zero).
> I write a unit test can stabilize repreduce.
> {code:java}
> // code placeholder
> public void testFileDecommission() throws Exception {
>   LOG.info("Starting test testFileDecommission");
>   final Path ecFile = new Path(ecDir, "testFileDecommission");
>   int writeBytes = cellSize * dataBlocks;
>   writeStripedFile(dfs, ecFile, writeBytes);
>   Assert.assertEquals(0, bm.numOfUnderReplicatedBlocks());
>   FileChecksum fileChecksum1 = dfs.getFileChecksum(ecFile, writeBytes);
>   LocatedBlocks locatedBlocks =
>       StripedFileTestUtil.getLocatedBlocks(ecFile, dfs);
>   LocatedBlock lb = dfs.getClient().getLocatedBlocks(ecFile.toString(), 0)
>       .get(0);
>   DatanodeInfo[] dnLocs = lb.getLocations();
>   LocatedStripedBlock lastBlock =
>       (LocatedStripedBlock)locatedBlocks.getLastLocatedBlock();
>   DatanodeInfo[] storageInfos = lastBlock.getLocations();
>   // 
>   DatanodeDescriptor datanodeDescriptor = cluster.getNameNode().getNamesystem()
>       .getBlockManager().getDatanodeManager().getDatanode(storageInfos[6].getDatanodeUuid());
>   for (int i = 0; i < 100; i++) {
>     datanodeDescriptor.incrementPendingReplicationWithoutTargets();
>   }
>   assertEquals(dataBlocks + parityBlocks, dnLocs.length);
>   int[] decommNodeIndex = {3, 4};
>   final List<DatanodeInfo> decommisionNodes = new ArrayList<DatanodeInfo>();
>   // add the node which will be decommissioning
>   decommisionNodes.add(dnLocs[decommNodeIndex[0]]);
>   decommisionNodes.add(dnLocs[decommNodeIndex[1]]);
>   decommissionNode(0, decommisionNodes, AdminStates.DECOMMISSIONED);
>   assertEquals(decommisionNodes.size(), fsn.getNumDecomLiveDataNodes());
>   //assertNull(checkFile(dfs, ecFile, 9, decommisionNodes, numDNs));
>   // Ensure decommissioned datanode is not automatically shutdown
>   DFSClient client = getDfsClient(cluster.getNameNode(0), conf);
>   assertEquals("All datanodes must be alive", numDNs,
>       client.datanodeReport(DatanodeReportType.LIVE).length);
>   FileChecksum fileChecksum2 = dfs.getFileChecksum(ecFile, writeBytes);
>   Assert.assertTrue("Checksum mismatches!",
>       fileChecksum1.equals(fileChecksum2));
>   StripedFileTestUtil.checkData(dfs, ecFile, writeBytes, decommisionNodes,
>       null, blockGroupSize);
> }
> {code}
>  



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