poorbarcode commented on code in PR #24096:
URL: https://github.com/apache/pulsar/pull/24096#discussion_r2006829543
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pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentSubscription.java:
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@@ -538,6 +556,127 @@ public void deleteFailed(ManagedLedgerException
exception, Object ctx) {
}
};
+ private void updatePendingAckMessagesAfterAcknowledged(Consumer ackFrom,
List<Position> positions) {
+ Dispatcher dispatcher0 = getDispatcher();
+ if (dispatcher0 != null) {
+ /*
+ * There is a race condition which leads us to add this
"synchronized" block.
+ * - consumer-1 received msg-A
+ * - consumption task is in-progress
+ * - topic was unloaded
+ * - reset messages to consumer-2
+ * At this moment, race-condition occurs:
+ * - consumer-1 is acknowledging msg-A
+ * - dispatcher is delivering msg-A to consumer-2
+ * Issue: broker received the acknowledging of msg-A, but no
consumer has pending acknowledge that relate
+ * to msg-A so broker can not know how many single messages in
the batched message.
+ * Solve: to get a precise messages number, this "synchronized"
block is needed.
+ */
+ synchronized (dispatcher0) {
Review Comment:
- There is a race condition which was described by the code comments.
- There are no other locks in the thread, `cursor.lock.writeLock()` has
released when execute `delete callback`
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