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From "Kihwal Lee (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-7990) IBR delete ack should not be delayed
Date Fri, 27 Mar 2015 14:08:54 GMT

     [ https://issues.apache.org/jira/browse/HDFS-7990?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kihwal Lee updated HDFS-7990:
-----------------------------
       Resolution: Fixed
    Fix Version/s: 2.8.0
     Hadoop Flags: Reviewed
           Status: Resolved  (was: Patch Available)

I've committed this to trunk and branch-2.

> IBR delete ack should not be delayed
> ------------------------------------
>
>                 Key: HDFS-7990
>                 URL: https://issues.apache.org/jira/browse/HDFS-7990
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 2.0.0-alpha
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>             Fix For: 2.8.0
>
>         Attachments: HDFS-7990.patch
>
>
> HDFS-395 added the incremental BR feature.  A concern was avoiding a race condition with
ack-ing block invalidates followed by the directory scanner re-adding the block before the
async delete service removes the block, possibly resulting in a full BR that includes the
previously delete ack-ed block.
> The solution was to batch & delay block deletion acks via a hardcoded interval of
100 * heartbeat interval (default: 5min).  The delay isn't required:
> #  The {{FSDatasetSpi}} tracks blocks pending deletions precisely so the scanner won't
re-add the block to the volume map
> # Block receiving, received, and deleted go into the same pending report.  A block received
event will trigger an immediate IBR which includes the deletion acks.  Ie. The delay is meaningless
for all but a quiescent cluster
> # Failing to promptly report deleted blocks on a quiescent cluster prevents the NN from
updating the block maps to remove the locations



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