[HDFS-4128] 2NN gets stuck in inconsistent state if edit log replay fails in the middle

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.2-alpha
• Fix Version/s: 0.23.7, 2.1.0-beta
• Component/s: namenode
• Target Version/s: 2.0.3-alpha
• Assignee: Kihwal Lee
• Reporter: Todd Lipcon
• Created: 29/Oct/12 21:24
• Updated: 03/Sep/14 22:55
• Resolved: 04/Mar/13 16:52

Description

We saw the following issue in a cluster:

• The 2NN downloads an edit log segment:

  2012-10-29 12:30:57,433 INFO org.apache.hadoop.hdfs.server.namenode.FSImage: Reading /xxxxxxx/current/edits_0000000000049136809-0000000000049176162 expecting start txid #49136809
  

• It fails in the middle of replay due to an OOME:

  2012-10-29 12:31:21,021 ERROR org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader: Encountered exception on operation AddOp [length=0, path=/xxxxxxxx
  java.lang.OutOfMemoryError: Java heap space
  

• Future checkpoints then fail because the prior edit log replay only got halfway through the stream:

  2012-10-29 12:32:21,214 INFO org.apache.hadoop.hdfs.server.namenode.FSImage: Reading /xxxxx/current/edits_0000000000049176163-0000000000049177224 expecting start txid #49144432
  2012-10-29 12:32:21,216 ERROR org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode: Exception in doCheckpoint
  java.io.IOException: There appears to be a gap in the edit log.  We expected txid 49144432, but got txid 49176163.
  

Issue Links

• is related to: HDFS-5074 Allow starting up from an fsimage checkpoint in the middle of a segment