hadoop-common-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-13208) listFiles(recursive=true) to do a bulk listObjects instead of walking the pseudo-tree of directories
Date Thu, 26 May 2016 20:59:12 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-13208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15302913#comment-15302913
] 

Steve Loughran commented on HADOOP-13208:
-----------------------------------------

One little detail, nothing has been written down about how listFiles() really works, there
are no FS contract tests. HADOOP-13207 covers this.

> listFiles(recursive=true) to do a bulk listObjects instead of walking the pseudo-tree
of directories
> ----------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-13208
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13208
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>    Affects Versions: 2.8.0
>            Reporter: Steve Loughran
>            Assignee: Steve Loughran
>            Priority: Minor
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> A major cost in split calculation against object stores turns out be listing the directory
tree itself. That's because against S3, it takes S3A two HEADs and two lists to list the content
of any directory path (2 HEADs + 1 list for getFileStatus(); the next list to query the contents).
> Listing a directory could be improved slightly by combining the final two listings. However,
a listing of a directory tree will still be O(directories). In contrast, a recursive {{listFiles()}}
operation should be implementable by a bulk listing of all descendant paths; one List operation
per thousand descendants. 
> As the result of this call is an iterator, the ongoing listing can be implemented within
the iterator itself



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: common-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: common-issues-help@hadoop.apache.org


Mime
View raw message