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https://issues.apache.org/jira/browse/HDFS-4128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13487392#comment-13487392
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Colin Patrick McCabe commented on HDFS-4128:
--------------------------------------------
Aborting definitely seems like the safest thing to do-- do we know that all
transactions are applied atomically (i.e. if they fail and throw an exception
in the middle, is there rollback of whatever they did to the FSImage?) I'm not
clear on that point.
> 2NN gets stuck in inconsistent state if edit log replay fails in the middle
> ---------------------------------------------------------------------------
>
> Key: HDFS-4128
> URL: https://issues.apache.org/jira/browse/HDFS-4128
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: name-node
> Affects Versions: 2.0.2-alpha
> Reporter: Todd Lipcon
>
> We saw the following issue in a cluster:
> - The 2NN downloads an edit log segment:
> {code}
> 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
> {code}
> - It fails in the middle of replay due to an OOME:
> {code}
> 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
> {code}
> - Future checkpoints then fail because the prior edit log replay only got
> halfway through the stream:
> {code}
> 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.
> {code}
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