Rajesh Balamohan created HDFS-9150:
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Summary: Consider implementing lazy seek in S3AInputStream
Key: HDFS-9150
URL: https://issues.apache.org/jira/browse/HDFS-9150
Project: Hadoop HDFS
Issue Type: Bug
Components: HDFS
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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