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From "Chris Nauroth (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-12444) Consider implementing lazy seek in S3AInputStream
Date Fri, 08 Apr 2016 18:05:25 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-12444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15232616#comment-15232616

Chris Nauroth commented on HADOOP-12444:

I am +1 for patch v007, pending commit of the pre-requisite HADOOP-12994 and a fresh pre-commit
run.  [~rajesh.balamohan], thank you for the patch.  [~stevel@apache.org], thank you for reviewing
and expanding the contract tests to improve coverage of this.

> Consider implementing lazy seek in S3AInputStream
> -------------------------------------------------
>                 Key: HADOOP-12444
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12444
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>    Affects Versions: 2.7.1
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>         Attachments: HADOOP-12444-004.patch, HADOOP-12444-005.patch, HADOOP-12444-006.patch,
HADOOP-12444-007.patch, HADOOP-12444.1.patch, HADOOP-12444.2.patch, HADOOP-12444.3.patch,
HADOOP-12444.WIP.patch, hadoop-aws-test-reports.tar.gz
> - Currently, "read(long position, byte[] buffer, int offset, int length)" is not implemented
in S3AInputStream (unlike DFSInputStream). So, "readFully(long position, byte[] buffer, int
offset, int length)" in S3AInputStream goes through the default implementation of seek(),
read(), seek() in FSInputStream. 
> - However, seek() in S3AInputStream involves re-opening of connection to S3 everytime
> - It would be good to consider having a lazy seek implementation to reduce connection
overheads to S3. (e.g Presto implements lazy seek. https://github.com/facebook/presto/blob/master/presto-hive/src/main/java/com/facebook/presto/hive/PrestoS3FileSystem.java#L623)

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