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https://issues.apache.org/jira/browse/HDFS-12978?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Shvachko updated HDFS-12978:
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Status: Patch Available (was: Open)
# The patch Introduces a configuration parameter to specify how many
transactions StandbyNode should process while holding the namesystem write lock.
# The default behavior is as in current code to process the entire segment
under the lock.
# I modified {{TestEditLogTailer}} to test 3 transactions per lock.
# The patch applies both to trunk and the feature branch. We may want to
consider applying this directly to trunk, since it could be useful when reads
from Standby are enabled, and stale reads are OK.
> Fine-grained locking while consuming journal stream.
> ----------------------------------------------------
>
> Key: HDFS-12978
> URL: https://issues.apache.org/jira/browse/HDFS-12978
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Konstantin Shvachko
> Assignee: Konstantin Shvachko
> Priority: Major
> Attachments: HDFS-12978.001.patch
>
>
> In current implementation SBN consumes the entire segment of transactions
> under a single namesystem lock, which does not allow reads over a long period
> of time until the segment is processed. We should break the lock into fine
> grained chunks. In extreme case each transaction should release the lock once
> it is applied.
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