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Date: Wed, 13 Jul 2016 13:58:20 +0000 (UTC)
From: "Steve Loughran (JIRA)" <jira@apache.org>
To: common-issues@hadoop.apache.org
Message-ID: <JIRA.12973196.1464296094000.16285.1468418300903@Atlassian.JIRA>
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Subject: [jira] [Updated] (HADOOP-13208) S3A listFiles(recursive=true) to do
 a bulk listObjects instead of walking the pseudo-tree of directories
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archived-at: Wed, 13 Jul 2016 13:58:23 -0000


     [ https://issues.apache.org/jira/browse/HADOOP-13208?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steve Loughran updated HADOOP-13208:
------------------------------------
    Attachment: HADOOP-13208-branch-2-011.patch

Patch 011: fix up TestS3ADirectoryPerformance to correctly validate the number of requests made during the listStatus() call, changed the assert to only expect two object list requests (the initial is-directory probe and the followup listing). Split the counter of object list requests into one for the initial request and one for followup actions.

> S3A 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
>         Attachments: HADOOP-13208-branch-2-001.patch, HADOOP-13208-branch-2-007.patch, HADOOP-13208-branch-2-008.patch, HADOOP-13208-branch-2-009.patch, HADOOP-13208-branch-2-010.patch, HADOOP-13208-branch-2-011.patch
>
>   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


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