[HDFS-5944] LeaseManager:findLeaseWithPrefixPath can't handle path like /a/b/ right and cause SecondaryNameNode failed do checkpoint

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.2.0, 2.2.0
• Fix Version/s: 1.3.0, 2.4.0
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: yunjiong zhao
• Reporter: yunjiong zhao
• Created: 13/Feb/14 03:43
• Updated: 10/Apr/14 13:11
• Resolved: 20/Feb/14 22:40

Description

In our cluster, we encountered error like this:
java.io.IOException: saveLeases found path /XXX/20140206/04_30/_SUCCESS.slc.log but is not under construction.
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.saveFilesUnderConstruction(FSNamesystem.java:6217)
at org.apache.hadoop.hdfs.server.namenode.FSImageFormat$Saver.save(FSImageFormat.java:607)
at org.apache.hadoop.hdfs.server.namenode.FSImage.saveCurrent(FSImage.java:1004)
at org.apache.hadoop.hdfs.server.namenode.FSImage.saveNamespace(FSImage.java:949)

What happened:
Client A open file /XXX/20140206/04_30/_SUCCESS.slc.log for write.
And Client A continue refresh it's lease.
Client B deleted /XXX/20140206/04_30/
Client C open file /XXX/20140206/04_30/_SUCCESS.slc.log for write
Client C closed the file /XXX/20140206/04_30/_SUCCESS.slc.log
Then secondaryNameNode try to do checkpoint and failed due to failed to delete lease hold by Client A when Client B deleted /XXX/20140206/04_30/.

The reason is a bug in findLeaseWithPrefixPath:
int srclen = prefix.length();
if (p.length() == srclen || p.charAt(srclen) == Path.SEPARATOR_CHAR)

{ entries.put(entry.getKey(), entry.getValue()); }

Here when prefix is /XXX/20140206/04_30/, and p is /XXX/20140206/04_30/SUCCESS.slc.log, p.charAt(srcllen) is ''.
The fix is simple, I'll upload patch later.