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Chris Nauroth commented on HADOOP-12444:
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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
(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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