[HBASE-20881] Introduce a region transition procedure to handle all the state transition for a region

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha-1, 2.2.0
• Component/s: amv2, proc-v2
• Hadoop Flags: Incompatible change, Reviewed

Release Note

Introduced a new TransitRegionStateProcedure to replace the old AssignProcedure/UnassignProcedure/MoveRegionProcedure. In the old code, MRP will not be attached to RegionStateNode, so it can not be interrupted by ServerCrashProcedure, which introduces lots of tricky code to deal with races, and also causes lots of other difficulties on how to prevent scheduling redundant or even conflict procedures for a region.

And now TRSP is the only one procedure which can bring region online or offline. When you want to schedule one, you need to check whether there is already one attached to the RegionStateNode, under the lock of the RegionStateNode. If not just go ahead, and if there is one, then you should do something, for example, give up and fail directly, or tell the TRSP to give up(This is what SCP does). Since the check and attach are both under the lock of RSN, it will greatly reduce the possible races, and make the code much simpler.

• Assignee: Duo Zhang
• Reporter: Duo Zhang
• Created: 13/Jul/18 02:37
• Updated: 07/Nov/23 04:36
• Resolved: 26/Aug/18 10:16

Description

Now have an AssignProcedure, an UnssignProcedure, and also a MoveRegionProcedure which schedules an AssignProcedure and an UnssignProcedure to move a region. This makes the logic a bit complicated, as MRP is not a RIT, so when SCP can not interrupt it directly...

Issue Links

• breaks: HBASE-21095 The timeout retry logic for several procedures are broken after master restarts
• contains: HBASE-21016 Find another way to test the backoff mechanism in TRSP
• is related to: HBASE-21075 Confirm that we can (rolling) upgrade from 2.0.x and 2.1.x to 2.2.x after HBASE-20881
• is related to: HBASE-21082 Reimplement assign/unassign related procedure metrics
• is related to: HBASE-21017 Revisit the expected states for open/close
• is related to: HBASE-21025 Add cache for TableStateManager
• links to: Review Board