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Posted to hdfs-dev@hadoop.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2012/09/19 04:49:07 UTC
[jira] [Created] (HDFS-3955) QJM: Make acceptRecovery() atomic
Todd Lipcon created HDFS-3955:
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Summary: QJM: Make acceptRecovery() atomic
Key: HDFS-3955
URL: https://issues.apache.org/jira/browse/HDFS-3955
Project: Hadoop HDFS
Issue Type: Sub-task
Components: ha
Affects Versions: QuorumJournalManager (HDFS-3077)
Reporter: Todd Lipcon
Assignee: Todd Lipcon
Per one of the TODOs in Journal.java, there is currently a lack of atomicity in the {{acceptRecovery()}} code path. In particular, we have the following actions executed non-atomically:
- Download a new edits_inprogress_N from some other node
- Persist the paxos recovery file to disk.
If the JN crashes between these two steps, then we may be left in the state whereby the edits_inprogress file has different data than the Paxos data left over on the disk from a previous recovery attempt. This causes the next {{prepareRecovery()}} to fail with an AssertionError.
I discovered this by randomly injecting a fault between the two steps, and then running the randomized fault test on a cluster. This resulted in some AssertionErrors in the test logs.
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[jira] [Resolved] (HDFS-3955) QJM: Make acceptRecovery() atomic
Posted by "Todd Lipcon (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/HDFS-3955?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Todd Lipcon resolved HDFS-3955.
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Resolution: Fixed
Fix Version/s: QuorumJournalManager (HDFS-3077)
Hadoop Flags: Reviewed
> QJM: Make acceptRecovery() atomic
> ---------------------------------
>
> Key: HDFS-3955
> URL: https://issues.apache.org/jira/browse/HDFS-3955
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha
> Affects Versions: QuorumJournalManager (HDFS-3077)
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: QuorumJournalManager (HDFS-3077)
>
> Attachments: hdfs-3955.txt
>
>
> Per one of the TODOs in Journal.java, there is currently a lack of atomicity in the {{acceptRecovery()}} code path. In particular, we have the following actions executed non-atomically:
> - Download a new edits_inprogress_N from some other node
> - Persist the paxos recovery file to disk.
> If the JN crashes between these two steps, then we may be left in the state whereby the edits_inprogress file has different data than the Paxos data left over on the disk from a previous recovery attempt. This causes the next {{prepareRecovery()}} to fail with an AssertionError.
> I discovered this by randomly injecting a fault between the two steps, and then running the randomized fault test on a cluster. This resulted in some AssertionErrors in the test logs.
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