Why Does the LoadIncrementalHFiles Tool Fail to Be Executed and "Permission denied" Is Displayed?

Question

Why does the LoadIncrementalHFiles tool fail to be executed and "Permission denied" is displayed when a Linux user is manually created in a normal cluster and DataNode in the cluster is used to import data in batches?

2020-09-20 14:53:53,808 WARN  [main] shortcircuit.DomainSocketFactory: error creating DomainSocket
java.net.ConnectException: connect(2) error: Permission denied when trying to connect to '/var/run/FusionInsight-HDFS/dn_socket'
	at org.apache.hadoop.net.unix.DomainSocket.connect0(Native Method)
	at org.apache.hadoop.net.unix.DomainSocket.connect(DomainSocket.java:256)
	at org.apache.hadoop.hdfs.shortcircuit.DomainSocketFactory.createSocket(DomainSocketFactory.java:168)
	at org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.nextDomainPeer(BlockReaderFactory.java:804)
	at org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.createShortCircuitReplicaInfo(BlockReaderFactory.java:526)
	at org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.create(ShortCircuitCache.java:785)
	at org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache.fetchOrCreate(ShortCircuitCache.java:722)
	at org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.getBlockReaderLocal(BlockReaderFactory.java:483)
	at org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.build(BlockReaderFactory.java:360)
	at org.apache.hadoop.hdfs.DFSInputStream.getBlockReader(DFSInputStream.java:663)
	at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:594)
	at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:776)
	at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:845)
	at java.io.DataInputStream.readFully(DataInputStream.java:195)
	at org.apache.hadoop.hbase.io.hfile.FixedFileTrailer.readFromStream(FixedFileTrailer.java:401)
	at org.apache.hadoop.hbase.io.hfile.HFile.isHFileFormat(HFile.java:651)
	at org.apache.hadoop.hbase.io.hfile.HFile.isHFileFormat(HFile.java:634)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.visitBulkHFiles(LoadIncrementalHFiles.java:1090)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.discoverLoadQueue(LoadIncrementalHFiles.java:1006)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.prepareHFileQueue(LoadIncrementalHFiles.java:257)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.doBulkLoad(LoadIncrementalHFiles.java:364)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.run(LoadIncrementalHFiles.java:1263)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.run(LoadIncrementalHFiles.java:1276)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.run(LoadIncrementalHFiles.java:1311)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
	at org.apache.hadoop.hbase.tool.LoadIncrementalHFiles.main(LoadIncrementalHFiles.java:1333)

Answer

If the client that the LoadIncrementalHFiles tool depends on is installed in the cluster and is on the same node as DataNode, HDFS creates short-circuit read during the execution of the tool to improve performance. The short-circuit read depends on the /var/run/FusionInsight-HDFS directory (dfs.domain.socket.path). The default permission on this directory is 750. This user does not have the permission to operate the directory.

To solve the preceding problem, perform the following operations:

Method 1: Create a user (recommended).

1. Create a user on Manager. By default, the user group contains the ficommon group.

   [root@xxx-xxx-xxx-xxx ~]# id test
   uid=20038(test) gid=9998(ficommon) groups=9998(ficommon)

2. Import data again.

Method 2: Change the owner group of the current user.

1. Add the user to the ficommon group.

   [root@xxx-xxx-xxx-xxx ~]# usermod -a -G ficommon test
   [root@xxx-xxx-xxx-xxx ~]# id test
   uid=2102(test) gid=2102(test) groups=2102(test),9998(ficommon)

2. Import data again.