HBASE-30169 Split completed parent region added to RIT list on host RS and master crash

[Umeshkumar9414]

• Bug: When a host RegionServer and master crashes, regionCrashed() blindly added all hosted regions to RIT, including split-completed parent regions that should never be reassigned.
  • Fix: Added isSplitOrMerged() guard in regionCrashed() to skip split/merged regions. Extracted isSplitOrMerged() and isReplica() helpers to reduce duplication with handleRegionStateNodeOperation().
  • Removed broken isRegionInTransition(RegionInfo) API — RegionInfo.COMPARATOR considers offline/split flags, so lookups failed when those flags differed between the query and stored instance. Replaced
    with encoded-name-based lookup in test utility.
  • Added test testRITWithSplitTableRegion — splits a region, crashes the hosting RS, restarts the master, and verifies the split parent is NOT in the RIT list.

[Copilot]

Pull request overview

Fixes an assignment tracking bug where split/merged parent regions could be incorrectly added to the master’s Regions-In-Transition (RIT) list during RegionServer crash handling, especially across master restarts. This improves correctness of assignment state tracking and adds regression coverage for the crash + master restart scenario.

Changes:

• Skip adding split/merged (and replica) regions to RIT during regionCrashed, and refactor shared guards into helpers.
• Remove the broken AssignmentManager.isRegionInTransition(RegionInfo) API and replace test checks with an encoded-name-based lookup helper.
• Add a regression test that splits a region, expires the hosting RS, restarts the master, and verifies the split parent is not in RIT.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransactionOnCluster.java	Updates tests to use the new encoded-name-based RIT check utility.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionSplit.java	Adds regression test for split-parent not appearing in RIT after RS+master crash/restart; modernizes a few assertions.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/AssignmentTestingUtil.java	Introduces encoded-name-based isRegionInTransition helper and updates existing wait helper to use it.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionInTransitionTracker.java	Adds split/merged guard in regionCrashed, extracts helper predicates, and removes the public containsKey-based RIT query method.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java	Removes the now-deleted isRegionInTransition(RegionInfo) API.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Umeshkumar9414]

Failing test is related to compaction. Unrelated to PR. Can look seperatly later.

[apurtell]

An AI assisted review finds:

This check isSplitOrMerged has been moved out of regionCrashed , where it formerly guarded calls to both visitRegionState and markRegionsAsCrashed. After this refactor, now only visitRegionState is guarded. A split parent in SPLIT state whose location is still equal to the crashed server (the parent stays in regionStates in this state until the catalog janitor cleans it) will now be processed in regionCrashed when this didn't used to be possible.

Recommendation:

Add & !AssignmentManagerUtil.isSplitOrMerged(node) to the if (crashedServerName.equals(node.getRegionLocation())) branch in markRegionsAsCrashed, just like the same check guard visitRegionState.