[jira] [Resolved] (HBASE-24994) Add hedgedReadOpsInCurThread metric

["Duo Zhang (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-24994?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Duo Zhang resolved HBASE-24994.
-------------------------------
    Fix Version/s: 2.4.0
                   1.7.0
     Hadoop Flags: Reviewed
       Resolution: Fixed

Merged to master, branch-2 and branch-1.

Thanks [~akiraluca] for contributing.

Mind filling the release note about the new metrics?

Thanks.

> Add hedgedReadOpsInCurThread metric
> -----------------------------------
>
>                 Key: HBASE-24994
>                 URL: https://issues.apache.org/jira/browse/HBASE-24994
>             Project: HBase
>          Issue Type: Improvement
>          Components: metrics
>            Reporter: Javier Akira Luca de Tena
>            Assignee: Javier Akira Luca de Tena
>            Priority: Minor
>             Fix For: 3.0.0-alpha-1, 1.7.0, 2.4.0
>
>
> When adding Hedged Reads metrics at https://issues.apache.org/jira/browse/HBASE-12220, hedgedReadOpsInCurThread was not included.
> I wonder if there was any reason to not include them. If not, I will provide pull request to include them soon.
>  
> Hedged reads use same thread pool for the original read:
>  [https://github.com/apache/hadoop/blob/0b8464d75227fcee2c6e7f2410377b3d53d3d5f8/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L1349-L1357]
>  When the executor is full and rejects the task, it will be executed in current thread, increasing this metric:
>  [https://github.com/apache/hadoop/blob/0b8464d75227fcee2c6e7f2410377b3d53d3d5f8/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java#L2913-L2918]
> This metric is very useful to determine if the hedged reads thread pool (dfs.client.hedged.read.threadpool.size) is undersized.



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