[jira] [Resolved] (HADOOP-19447) Add Caching Mechanism to HostResolver to Avoid Redundant Hostname Resolutions

["Shilun Fan (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-19447?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shilun Fan resolved HADOOP-19447.
---------------------------------
       Fix Version/s: 3.5.0
        Hadoop Flags: Reviewed
    Target Version/s: 3.5.0
          Resolution: Fixed

> Add Caching Mechanism to HostResolver to Avoid Redundant Hostname Resolutions
> -----------------------------------------------------------------------------
>
>                 Key: HADOOP-19447
>                 URL: https://issues.apache.org/jira/browse/HADOOP-19447
>             Project: Hadoop Common
>          Issue Type: New Feature
>          Components: common, yarn
>            Reporter: Jiandan Yang 
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 3.5.0
>
>
> *Background:*
>  
> Currently, the two implementations of org.apache.hadoop.security.SecurityUtil.HostResolver, *StandardHostResolver and QualifiedHostResolver* in Hadoop performs hostname resolution each time it is called. *Each heartbeat between the AM and RM causes the RM to invoke the* HostResolver#getByName {*}method once{*}. In large-scale clusters running numerous applications, this results in *a high frequency of redundant hostname resolutions.*
>  
> *Proposal:*
>  
> Introduce a caching mechanism in HostResolver to store resolved hostnames for a configurable duration. This would:
> •Reduce redundant DNS queries.
> •Improve performance for frequently used hostnames.
> •Allow configuration options for cache size and TTL (Time-to-Live).
>  
> *Suggested Implementation:*
> 1.{*}Leverage Existing CachedResolver{*}:
> The NodesListManager.CachedResolver class in Hadoop already implements a caching mechanism for hostname resolution. Instead of introducing an entirely new solution, we propose *extracting the caching logic from* NodesListManager.CachedResolver {*}into a separate reusable utility class{*}.
> 2.{*}Create a Shared Caching Utility{*}:
> •Extract the caching logic from NodesListManager.CachedResolver.
> •Implement a new class, e.g., HostnameCache, and place it in the Hadoop Common module to ensure it can be used across different components.
> 3.{*}Integrate{*} HostnameCache with *HostResolver &QualifiedHostResolver*:
> •Modify HostResolver to use HostnameCache for hostname lookups.
> •Update NodesListManager.CachedResolver to use HostnameCache instead of its own internal cache.



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