[HBASE-14465] Backport 'Allow rowlock to be reader/write' to branch-1

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0, 1.3.0
• Component/s: regionserver
• Hadoop Flags: Incompatible change, Reviewed

Release Note

Locks on row are now reader/writer rather than exclusive.

Moves sequenceid out of HRegion and into MVCC class; MVCC is now in charge. A WAL append is still stamped in same way (we pass MVCC context in a few places where we previously we did not).

MVCC methods cleaned up. Make a bit more sense now. Less of them.

Simplifies our update of MemStore/WAL. Now we update memstore AFTER we add to WAL (but before we sync). This fixes possible dataloss when two edits came in with same coordinates; we could order the edits in memstore differently to how they arrived in the WAL.

Marked as an incompatible change because it breaks Distributed Log Replay, a feature we'd determined already was unreliable and to be removed (See http://search-hadoop.com/m/YGbbhTJpoal8GD1).

• Assignee: Michael Stack
• Reporter: Michael Stack
• Created: 23/Sep/15 00:58
• Updated: 17/Jun/22 18:44
• Resolved: 30/Sep/15 19:44

Description

Backport to branch-1.

You want this in 1.2 busbey? Its cleanup and fixes a possible dataloss. On other hand, its a bit of refactoring.

Issue Links

• breaks: HBASE-17069 RegionServer writes invalid META entries for split daughters in some circumstances
• causes: HBASE-20146 Regions are stuck while opening when WAL is disabled