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[improve][broker]Optimize InMemoryDelayedDeliveryTracker by maintaining state #23918

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[improve][broker]Optimize InMemoryDelayedDeliveryTracker by maintaining state #23918

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19 changes: 18 additions & 1 deletion ...broker/src/main/java/org/apache/pulsar/broker/delayed/InMemoryDelayedDeliveryTracker.java
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Original file line number Diff line number Diff line change
Expand Up @@ -218,9 +218,26 @@ public NavigableSet<Position> getScheduledMessages(int maxMessages) {
return positions;
}

public boolean shouldSkipMessage(long ledgerId, long entryId) {
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it better to keep the method name with BucketDelayedDeliveryTracker, change shouldSkipMessage to contains.

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@yunmaoQu yunmaoQu Feb 3, 2025 •
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@dao-jun ok

for (Long2ObjectMap<Roaring64Bitmap> ledgerMap : delayedMessageMap.values()) {
Roaring64Bitmap entryIds = ledgerMap.get(ledgerId);
if (entryIds != null && entryIds.contains(entryId)) {
return true;
}
}
return false;
}

@Override
public CompletableFuture<Void> clear() {
this.delayedMessageMap.clear();
long cutoffTime = getCutoffTime();
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why only clear expired index?

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@yunmaoQu yunmaoQu Feb 3, 2025 •
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@dao-jun The decision to clear only expired indices in the clear() method of the InMemoryDelayedDeliveryTracker is aimed at optimizing performance and maintaining the logical state of the message delivery system.

By focusing on expired messages, we reduce the overhead associated with clearing and re-adding valid messages, which enhances performance, especially in scenarios with a high volume of delayed messages. This approach also allows us to retain the state of valid messages, enabling more efficient message delivery without needing to re-read them from storage.

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I doubt that it will introduce memory leak problem. For example, we need to clear all delayed messages at method:
org.apache.pulsar.broker.service.persistent.PersistentDispatcherMultipleConsumers#clearDelayedMessages

IMO, the payoff of re-adding valid messages for once is acceptable, while the risk of such change is great.

delayedMessageMap.headMap(cutoffTime).clear();

if (log.isDebugEnabled()) {
log.debug("[{}] Cleared expired delayed messages before {}, remaining messages: {}",
dispatcher.getName(), cutoffTime, getNumberOfDelayedMessages());
}

return CompletableFuture.completedFuture(null);
}

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11 changes: 4 additions & 7 deletions ...va/org/apache/pulsar/broker/service/persistent/PersistentDispatcherMultipleConsumers.java
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Original file line number Diff line number Diff line change
Expand Up @@ -193,12 +193,6 @@ public synchronized CompletableFuture<Void> addConsumer(Consumer consumer) {
shouldRewindBeforeReadingOrReplaying = false;
}
redeliveryMessages.clear();
delayedDeliveryTracker.ifPresent(tracker -> {
// Don't clean up BucketDelayedDeliveryTracker, otherwise we will lose the bucket snapshot
if (tracker instanceof InMemoryDelayedDeliveryTracker) {
tracker.clear();
}
});
}

if (isConsumersExceededOnSubscription()) {
Expand Down Expand Up @@ -448,7 +442,10 @@ protected Predicate<Position> createReadEntriesSkipConditionForNormalRead() {
// Filter out and skip read delayed messages exist in DelayedDeliveryTracker
if (delayedDeliveryTracker.isPresent()) {
final DelayedDeliveryTracker deliveryTracker = delayedDeliveryTracker.get();
if (deliveryTracker instanceof BucketDelayedDeliveryTracker) {
if (deliveryTracker instanceof InMemoryDelayedDeliveryTracker) {
skipCondition = position -> ((InMemoryDelayedDeliveryTracker) deliveryTracker)
.shouldSkipMessage(position.getLedgerId(), position.getEntryId());
} else if (deliveryTracker instanceof BucketDelayedDeliveryTracker) {
skipCondition = position -> ((BucketDelayedDeliveryTracker) deliveryTracker)
.containsMessage(position.getLedgerId(), position.getEntryId());
Comment on lines -451 to 450
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@thetumbled thetumbled Feb 18, 2025 •
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change shouldSkipMessage to contains to avoid duplicate code.

}
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