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https://issues.apache.org/jira/browse/HADOOP-17975?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Stephen O'Donnell resolved HADOOP-17975.
----------------------------------------
Resolution: Fixed
> Fallback to simple auth does not work for a secondary DistributedFileSystem
> instance
> ------------------------------------------------------------------------------------
>
> Key: HADOOP-17975
> URL: https://issues.apache.org/jira/browse/HADOOP-17975
> Project: Hadoop Common
> Issue Type: Bug
> Components: ipc
> Reporter: István Fajth
> Assignee: István Fajth
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.4.0, 3.2.4, 3.3.3
>
> Time Spent: 10h 10m
> Remaining Estimate: 0h
>
> The following code snippet demonstrates what is necessary to cause a failure
> in connection to a non secure cluster with fallback to SIMPLE auth allowed
> from a secure cluster.
> {code:java}
> Configuration conf = new Configuration();
> conf.setBoolean("ipc.client.fallback-to-simple-auth-allowed", true);
> URI fsUri = new URI("hdfs://<nn_uri>");
> conf.setBoolean("fs.hdfs.impl.disable.cache", true);
> FileSystem fs = FileSystem.get(fsUri, conf);
> FSDataInputStream src = fs.open(new Path("/path/to/a/file"));
> FileOutputStream dst = new FileOutputStream(File.createTempFile("foo",
> "bar"));
> IOUtils.copyBytes(src, dst, 1024);
> // The issue happens even if we re-enable cache at this point
> //conf.setBoolean("fs.hdfs.impl.disable.cache", false);
> // The issue does not happen when we close the first FileSystem object
> // before creating the second.
> //fs.close();
> FileSystem fs2 = FileSystem.get(fsUri, conf);
> FSDataInputStream src2 = fs2.open(new Path("/path/to/a/file"));
> FileOutputStream dst2 = new FileOutputStream(File.createTempFile("foo",
> "bar"));
> IOUtils.copyBytes(src2, dst2, 1024);
> {code}
> The problem is that when the DfsClient is created it creates an instance of
> AtomicBoolean, which is propagated down into the IPC layer, where the
> Client.Connection instance in setupIOStreams sets its value. This connection
> object is cached and re-used to multiplex requests against the same DataNode.
> In case of creating a second DfsClient, the AtomicBoolean reference in the
> client is a new AtomicBoolean, but the Client.Connection instance is the
> same, and as it has a socket already open to the DataNode, it returns
> immediatelly from setupIOStreams, leaving the fallbackToSimpleAuth
> AtomicBoolean false as it is created in the DfsClient.
> This AtomicBoolean on the other hand controls how the SaslDataTransferClient
> handles the connection in the above level, and with this value left on the
> default false, the SaslDataTransferClient of the second DfsClient will not
> fall back to SIMPLE authentication but will try to send a SASL handshake when
> connecting to the DataNode.
>
> The access to the FileSystem via the second DfsClient fails with exceptions
> like the following one, then fails the read with a BlockMissingException like
> below:
> {code}
> WARN hdfs.DFSClient: Failed to connect to /<dn_ip>:<dn_port> for file <file>
> for block BP-531773307-<nn_ip>-1634685133591:blk_1073741826_1002, add to
> deadNodes and continue.
> java.io.EOFException: Unexpected EOF while trying to read response from server
> at
> org.apache.hadoop.hdfs.protocolPB.PBHelperClient.vintPrefixed(PBHelperClient.java:552)
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.sasl.DataTransferSaslUtil.readSaslMessage(DataTransferSaslUtil.java:215)
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.doSaslHandshake(SaslDataTransferClient.java:455)
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.getSaslStreams(SaslDataTransferClient.java:393)
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.send(SaslDataTransferClient.java:267)
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.checkTrustAndSend(SaslDataTransferClient.java:215)
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.peerSend(SaslDataTransferClient.java:160)
> at
> org.apache.hadoop.hdfs.DFSUtilClient.peerFromSocketAndKey(DFSUtilClient.java:648)
> at
> org.apache.hadoop.hdfs.DFSClient.newConnectedPeer(DFSClient.java:2980)
> at
> org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.nextTcpPeer(BlockReaderFactory.java:822)
> at
> org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:747)
> at
> org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.build(BlockReaderFactory.java:380)
> at
> org.apache.hadoop.hdfs.DFSInputStream.getBlockReader(DFSInputStream.java:658)
> at
> org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:589)
> at
> org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:771)
> at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:840)
> at java.io.DataInputStream.read(DataInputStream.java:100)
> at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:94)
> at DfsClientTest3.main(DfsClientTest3.java:30)
> {code}
> {code}
> org.apache.hadoop.hdfs.BlockMissingException: Could not obtain block:
> BP-813026743-<nn_ip>-1495248833293:blk_1139767762_66027405 file=/path/to/file
> {code}
>
> The DataNode in the meantime logs the following:
> {code}
> ERROR org.apache.hadoop.hdfs.server.datanode.DataNode:
> <dn_host>:<dn_port>:DataXceiver error processing unknown operation src:
> /<client_ip>:<client_port> dst: /<dn_ip>:<dn_port>
> java.io.IOException: Version Mismatch (Expected: 28, Received: -8531 )
> at
> org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.readOp(Receiver.java:70)
> at
> org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:222)
> at java.lang.Thread.run(Thread.java:748)
> {code}
> This happens only if the second client is connecting to the same DataNode as
> the first one did, so might seem intermittent in case the clients are reading
> different files, but happens always if the two client reads the same file
> with replication factor 1.
> We ran into this issue during running HBase ExportSnapshot tool to move a
> snapshot from a non-secure to a secure cluster, the issue is loosely related
> to HBASE-12819 and HBASE-20433 and similar problems, I am linking these so
> that HBase team will see how this is relevant for them.
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