[HADOOP-13047] S3a Forward seek in stream length to be configurable

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.8.0
• Component/s: fs/s3
• Assignee: Steve Loughran
• Reporter: Steve Loughran
• Created: 21/Apr/16 19:10
• Updated: 12/May/16 18:26
• Resolved: 12/May/16 18:26

Description

Even with lazy seek, tests can show that sometimes a short-distance forward seek is triggering a close + reopen, because the threshold for the seek is simply available bytes in the inner stream.

A configurable threshold would allow data to be read and discarded before that seek. This should be beneficial over long-haul networks as the time to set up the TCP channel is high, and TCP-slow-start means that the ramp up of bandwidth is slow. In such deployments, it will better to read forward than re-open, though the exact "best" number will vary with client and endpoint.

Issue Links

• Is contained by: HADOOP-13028 add low level counter metrics for S3A; use in read performance tests