[HDFS-10519] Add a configuration option to enable in-progress edit log tailing

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha1
• Component/s: ha
• Target Version/s: 2.9.0
• Release Note: Add a configuration option to enable in-progress edit tailing and a related unit test
• Assignee: Jiayi Zhou
• Reporter: Jiayi Zhou
• Created: 13/Jun/16 21:13
• Updated: 31/Oct/19 00:21
• Resolved: 28/Jul/16 00:59

Description

Standby Namenode has the option to do in-progress edit log tailing to improve the data freshness. In-progress tailing is already implemented, but it's not enabled as default configuration. And there's no related configuration key to turn it on.
Adding a related configuration key to let Standby Namenode is reasonable and would be a basis for further improvement on Standby Namenode.

Issue Links

• breaks: HDFS-13145 SBN crash when transition to ANN with in-progress edit tailing enabled
• is depended upon by: HDFS-10702 Add a Client API and Proxy Provider to enable stale read from Standby
• is related to: HDFS-14317 Standby does not trigger edit log rolling when in-progress edit log tailing is enabled
• is related to: HDFS-10877 Make RemoteEditLogManifest.committedTxnId optional in Protocol Buffers
• relates to: HDFS-12836 startTxId could be greater than endTxId when tailing in-progress edit log
• relates to: HDFS-13145 SBN crash when transition to ANN with in-progress edit tailing enabled
• relates to: HDFS-12943 Consistent Reads from Standby Node