[HBASE-25596] Fix NPE in ReplicationSourceManager as well as avoid permanently unreplicated data due to EOFException from WAL

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha-1, 1.7.0, 2.5.0, 2.4.2
• Component/s: Replication
• Hadoop Flags: Reviewed
• Assignee: Sandeep Pal
• Reporter: Sandeep Pal
• Created: 22/Feb/21 21:48
• Updated: 02/Jul/21 03:10
• Resolved: 03/Mar/21 19:41

Description

There seems to be a major issue with how we handle the EOF exception from WALEntryStream. 

Problem:

When we see EOFException, we try to handle it and remove it from the log queue, but we never try to ship the existing batch of entries. This is a permanent data loss in replication.

 

Secondly, we do not stop the reader on encountering the EOFException and thus if EOFException was on the last WAL, we still try to process the WALEntry stream and ship the empty batch with lastWALPath set to null. This is the reason of NPE as below which crash the region server. 

2021-02-16 15:33:21,293 ERROR [,60020,1613262147968] regionserver.ReplicationSource - Unexpected exception in ReplicationSourceWorkerThread, currentPath=nulljava.lang.NullPointerExceptionat org.apache.hadoop.hbase.replication.regionserver.ReplicationSourceManager.logPositionAndCleanOldLogs(ReplicationSourceManager.java:193)at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceShipperThread.updateLogPosition(ReplicationSource.java:831)at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceShipperThread.shipEdits(ReplicationSource.java:746)at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceShipperThread.run(ReplicationSource.java:650)2021-02-16 15:33:21,294 INFO [,60020,1613262147968] regionserver.HRegionServer - STOPPED: Unexpected exception in ReplicationSourceWorkerThread

 

 

Issue Links

• links to: GitHub Pull Request #2975
• links to: GitHub Pull Request #2987
• links to: GitHub Pull Request #2990
• links to: GitHub Pull Request #3008

Sub-Tasks

• Backport HBASE-25596 and HBASE-25992 to branch-2.3: Open
• ReplicationSourceWALReader#run - Reset sleepMultiplier in loop once out of any IOE: Resolved
• Polish the ReplicationSourceWALReader code for 2.x after HBASE-25596: Resolved