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https://issues.apache.org/jira/browse/HDFS-6315?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13990064#comment-13990064
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Daryn Sharp commented on HDFS-6315:
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I am also working towards the goal of removing or minimizing the use of the FSD
lock, but I recall it's being used to protect non-threadsafe data structures
(like the inode map and snapshot manager). It's spurred by the work to add
fine grain locking to the namesystem - which has been derailed by other
pressing issues. Do keep in mind that hopefully in the next few months there
will not be a globally held FSN so don't entirely remove the FSD lock believing
the FSN lock will cover for it.
bq. The change can be reverted when removing the lock of FSDirectory.
I'm curious what you have in mind. HDFS-5693 appears to be a valuable change.
I thoughts deletes used to do something similar while collecting blocks, but
that whole region of code has been changed.
> 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
>
>
> 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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