[jira] [Commented] (HDFS-17896) Move logAllocatedBlock out of lock in FSNamesystem.getAdditionalBlock to reduce latency

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-17896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18070182#comment-18070182 ] 

ASF GitHub Bot commented on HDFS-17896:
---------------------------------------

CapMoon commented on PR #8360:
URL: https://github.com/apache/hadoop/pull/8360#issuecomment-4166684461

   Failed UTs are not relevant to this pr.




> Move logAllocatedBlock out of lock in FSNamesystem.getAdditionalBlock to reduce latency
> ---------------------------------------------------------------------------------------
>
>                 Key: HDFS-17896
>                 URL: https://issues.apache.org/jira/browse/HDFS-17896
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs
>    Affects Versions: 3.4.3
>            Reporter: yue.wang
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: logAllocatedBlock takes lots of time.png
>
>
> The {{logAllocatedBlock}} method in {{FSNamesystem.getAdditionalBlock}} is currently called while holding global lock. Flame graph analysis shows this logging path (via SLF4J/Log4j appenders) contributes non-trivial latency, blocking other NameNode operations.
>  
> Since {{logAllocatedBlock}} is only for audit/diagnostic logging and does not modify shared state, we can safely move it after releasing global lock to reduce lock hold time and improve write throughput.
>  
> This change preserves all existing logging behavior while eliminating unnecessary lock contention from I/O-bound logging operations.
>  
> Flame graph:



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