[jira] [Commented] (HADOOP-18740) s3a prefetch cache blocks should be accessed by RW locks

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

    [ https://issues.apache.org/jira/browse/HADOOP-18740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17727670#comment-17727670 ] 

ASF GitHub Bot commented on HADOOP-18740:
-----------------------------------------

MayankSinghParmar commented on PR #5675:
URL: https://github.com/apache/hadoop/pull/5675#issuecomment-1568970535

   I want to implement a new cache replacement algorithm in hdfs but I don't know which part of module to use and modify. Can any one please help me find the modules and functions which need to override to add my own caching replacement algorithm in hdfs




> s3a prefetch cache blocks should be accessed by RW locks
> --------------------------------------------------------
>
>                 Key: HADOOP-18740
>                 URL: https://issues.apache.org/jira/browse/HADOOP-18740
>             Project: Hadoop Common
>          Issue Type: Sub-task
>            Reporter: Viraj Jasani
>            Assignee: Viraj Jasani
>            Priority: Major
>
> In order to implement LRU or LFU based cache removal policies for s3a prefetched cache blocks, it is important for all cache reader threads to acquire read lock and similarly cache file removal mechanism (fs close or cache eviction) to acquire write lock before accessing the files.
> As we maintain the block entries in an in-memory map, we should be able to introduce read-write lock per cache file entry, we don't need coarse-grained lock shared by all entries.
>  
> This is a prerequisite to HADOOP-18291.



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