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https://issues.apache.org/jira/browse/HDFS-6315?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14020181#comment-14020181
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Haohui Mai commented on HDFS-6315:
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The v2 patch moves all edit log operations into {{FSNameSystem}} except for
{{rename}} and {{delete}}. These two functions require more changes thus I plan
to address them in a separate jira.
The patch makes the following changes:
# It moves the edit log operations of {{setReplication}}, {{setPermission}},
{{setOwner}}, {{concat}}, {{setQuota}}, and all ACL / XAttr operations into
their respective callees.
# The patch moves {{persistBlock}} and {{persistNewBlock}} into FSDirectory.
The original code protects these two methods with the lock of the
{{FSDirectory}}. The patch moves them out of the lock because these two methods
only log the edit logs, where the logging itself has been made synchronized in
the {{EditLog}} class.
With the above changes, this patch no longer leaks the lock of the
{{FSDirectory}} into {{FSNameSystem}}. [~daryn], do you have any more comments?
> Decouple recording edit logs from FSDirectory
> ---------------------------------------------
>
> Key: HDFS-6315
> URL: https://issues.apache.org/jira/browse/HDFS-6315
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Haohui Mai
> Assignee: Haohui Mai
> Attachments: HDFS-6315.000.patch, HDFS-6315.001.patch,
> HDFS-6315.002.patch
>
>
> Currently both FSNamesystem and FSDirectory record edit logs. This design
> requires both FSNamesystem and FSDirectory to be tightly coupled together to
> implement a durable namespace.
> This jira proposes to separate the responsibility of implementing the
> namespace and providing durability with edit logs. Specifically, FSDirectory
> implements the namespace (which should have no edit log operations), and
> FSNamesystem implement durability by recording the edit logs.
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