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https://issues.apache.org/jira/browse/HDFS-4128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13590586#comment-13590586
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Daryn Sharp commented on HDFS-4128:
-----------------------------------
Patch looks straightforward. A few comments:
* Default of 60 retries seems a bit high, esp. for a cluster with a large image
and edits. I'd think something like the standard 3 would be sufficient because
if the 2NN aborts it will get the attention faster of the admin.
* I think ">= maxRetries" should be ">" because ">=" means attempts instead of
retries. Ie. Currently if I specify 1 max retry, it doesn't retry at all.
* Given the former issue, there should be a test that maxRetries is actually
honored.
* Spelling police told me "occured" should be "occurred" :)
> 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: namenode
> Affects Versions: 2.0.2-alpha
> Reporter: Todd Lipcon
> Assignee: Kihwal Lee
> Attachments: hdfs-4128.patch
>
>
> 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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