Copilot commented on code in PR #8584:
URL: https://github.com/apache/hbase/pull/8584#discussion_r3918125748
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hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java:
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@@ -1092,6 +1092,24 @@ public void removeRegion(final RegionInfo regionInfo) {
flushedSequenceIdByRegion.remove(encodedName);
}
+ /**
+ * Called on region OPEN to seed {@link #flushedSequenceIdByRegion} with the
region's
+ * {@code openSeqNum}. Without this, the entry stays absent until the
hosting server's next
+ * heartbeat, so {@link #getLastFlushedSequenceId} returns {@link
HConstants#NO_SEQNUM} and
+ * WALSplitter conservatively treats already-durable edits as unflushed -
producing orphaned
+ * recovered.edits when the source server crashes soon after a drain-move.
Uses {@code merge} with
+ * {@link Math#max} so a heartbeat-supplied value (which may reflect flushes
after open) is never
+ * regressed - and, unlike {@code putIfAbsent}, a stale-low prior value is
lifted to
+ * {@code openSeqNum}. Safe because at OPEN a region cannot have flushed
past its own
+ * {@code openSeqNum}. See HBASE-30335.
+ */
+ public void reportRegionOpen(final RegionInfo regionInfo, final long
openSeqNum) {
+ if (openSeqNum < 0) { // NO_SEQNUM == -1
+ return;
+ }
+ flushedSequenceIdByRegion.merge(regionInfo.getEncodedNameAsBytes(),
openSeqNum, Math::max);
Review Comment:
This `merge` is atomic, but the heartbeat writer is not:
`updateLastFlushedSequenceIds` reads the current value at line 292 and later
performs a conditional `put` at line 300. An in-flight stale heartbeat can
therefore read an absent entry, this call can install `openSeqNum`, and then
the heartbeat can overwrite it with an older completed sequence ID, violating
the monotonic watermark guarantee and potentially restoring the WAL-splitting
failure. Please make the heartbeat update use the same atomic max operation and
cover this interleaving in the test.
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