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From "Thomas Demoor (JIRA)" <j...@apache.org>
Subject [jira] [Moved] (HADOOP-12444) Consider implementing lazy seek in S3AInputStream
Date Mon, 28 Sep 2015 07:51:04 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-12444?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Thomas Demoor moved HDFS-9150 to HADOOP-12444:
----------------------------------------------

    Component/s:     (was: HDFS)
     Issue Type: Improvement  (was: Bug)
            Key: HADOOP-12444  (was: HDFS-9150)
        Project: Hadoop Common  (was: Hadoop HDFS)

> Consider implementing lazy seek in S3AInputStream
> -------------------------------------------------
>
>                 Key: HADOOP-12444
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12444
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Rajesh Balamohan
>
> - 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
(https://github.com/apache/hadoop/blob/trunk/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AInputStream.java#L115).
 
> - 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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