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https://issues.apache.org/jira/browse/HDFS-17509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17845171#comment-17845171
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ASF GitHub Bot commented on HDFS-17509:
---------------------------------------
ZanderXu commented on code in PR #6784:
URL: https://github.com/apache/hadoop/pull/6784#discussion_r1596183555
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hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterClientProtocol.java:
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@@ -667,39 +667,28 @@ public void rename2(final String src, final String dst,
public void concat(String trg, String[] src) throws IOException {
rpcServer.checkOperation(NameNode.OperationCategory.WRITE);
- // See if the src and target files are all in the same namespace
- LocatedBlocks targetBlocks = getBlockLocations(trg, 0, 1);
- if (targetBlocks == null) {
- throw new IOException("Cannot locate blocks for target file - " + trg);
- }
- LocatedBlock lastLocatedBlock = targetBlocks.getLastLocatedBlock();
- String targetBlockPoolId = lastLocatedBlock.getBlock().getBlockPoolId();
- for (String source : src) {
- LocatedBlocks sourceBlocks = getBlockLocations(source, 0, 1);
- if (sourceBlocks == null) {
- throw new IOException(
- "Cannot located blocks for source file " + source);
- }
- String sourceBlockPoolId =
- sourceBlocks.getLastLocatedBlock().getBlock().getBlockPoolId();
- if (!sourceBlockPoolId.equals(targetBlockPoolId)) {
- throw new IOException("Cannot concatenate source file " + source
- + " because it is located in a different namespace"
- + " with block pool id " + sourceBlockPoolId
- + " from the target file with block pool id "
- + targetBlockPoolId);
- }
- }
+ // Concat only effects when all files in same namespace.
+ // And in router view, a file only exists in one RemoteLocation.
Review Comment:
> For a file in Router view with more than one nameservices, I think should
thrown Exception for concat method.
For multiple namespaces contain one same file case, RBF just return the file
in the first namespace currently, such as: getBlockLocation, getFileInfo, etc.
So If you want to thrown Exception for concat, maybe you need to modify all
RPCs to throw Exception for this case.
May we can use getFileInfo instead of getBlockLocation to fix this bug. BTW,
getFileInfo is no needed if this path only mounts to one namespace.
> RBF: Fix ClientProtocol.concat will throw NPE if tgr is a empty file.
> ----------------------------------------------------------------------
>
> Key: HDFS-17509
> URL: https://issues.apache.org/jira/browse/HDFS-17509
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: liuguanghua
> Priority: Minor
> Labels: pull-request-available
>
> hdfs dfs -concat /tmp/merge /tmp/t1 /tmp/t2
> When /tmp/merge is a empty file, this command will throw NPE via DFSRouter.
>
>
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