[HBASE-7050] Document locking of HRegion

• Type: Task
• Status: Closed
• Priority: Minor
• Resolution: Not A Problem
• Component/s: documentation, Transactions/MVCC
• Assignee: Unassigned
• Reporter: Gregory Chanan
• Created: 25/Oct/12 03:07
• Updated: 14/Jun/22 22:17
• Resolved: 14/Jun/22 22:17

Description

Would be good to have some documentation on the locking in HRegion. In particular, the updateLock and the row locks.

With the optimizations that have been made, e.g. HBASE-5541 this isn't straightforward.

When do these locks need to be held? What structures do they protect access to? Why does the updateLock not need to be held during rollback? Those sorts of questions.

I've started do to some of this, but haven't fully fleshed it out.