[Caideyipi]

Summary

Subscription polling and batch emission copy regionIdToBatch.keySet() while the prefetch path may structurally update the same map under per-region locks. A concurrent update can make the snapshot fail and abort polling.

Use ConcurrentHashMap for region batch tracking while retaining the existing per-region locks for batch operations. Add a regression test that runs poll and emit snapshots alongside prefetch-style inserts and removals.

Validation

• mvn spotless:apply -P with-integration-tests -pl iotdb-core/datanode
• mvn -o -pl iotdb-core/datanode -am clean test -Dtest=SubscriptionPipeEventBatchesConcurrencyTest -Dsurefire.failIfNoSpecifiedTests=false (28 reactor modules; 1 test passed)

[sonarqubecloud]

Quality Gate failed

Failed conditions
C Reliability Rating on New Code (required ≥ A)

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[Caideyipi]

Initial independent self-review for PR head d392b0b against master.

The complete diff and relevant subscription batch, segment-lock, and prefetch queue lifecycle paths were inspected. No actionable issues were found, and no fixes were needed. The ConcurrentHashMap change safely supports concurrent region-key snapshots while preserving the existing per-region locks.

Local verification: the newly added concurrency regression test was reported passing locally; it was not rerun during this review round. The local checkout remained master at 65ef92f; the confirmed remote PR head is d392b0b.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 48.28%. Comparing base (65ef92f) to head (d392b0b).

Files with missing lines	Patch %	Lines
...tion/event/batch/SubscriptionPipeEventBatches.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #19116      +/-   ##
============================================
- Coverage     48.29%   48.28%   -0.01%     
  Complexity      625      625              
============================================
  Files          5572     5572              
  Lines        411719   411719              
  Branches      54229    54229              
============================================
- Hits         198820   198798      -22     
- Misses       212899   212921      +22     

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