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[pulsar-broker] Fix Deadlock by Consumer and Reader #6728

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Apr 14, 2020
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[pulsar-broker] Fix Deadlock by Consumer and Reader #6728

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76 changes: 39 additions & 37 deletions pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java
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Original file line number Diff line number Diff line change
Expand Up @@ -692,49 +692,51 @@ private CompletableFuture<? extends Subscription> getNonDurableSubscription(Stri
CompletableFuture<Subscription> subscriptionFuture = new CompletableFuture<>();
log.info("[{}][{}] Creating non-durable subscription at msg id {}", topic, subscriptionName, startMessageId);

// Create a new non-durable cursor only for the first consumer that connects
Subscription subscription = subscriptions.computeIfAbsent(subscriptionName, name -> {
MessageIdImpl msgId = startMessageId != null ? (MessageIdImpl) startMessageId
: (MessageIdImpl) MessageId.latest;

long ledgerId = msgId.getLedgerId();
long entryId = msgId.getEntryId();
if (ledgerId >= 0
&& msgId instanceof BatchMessageIdImpl) {
// When the start message is relative to a batch, we need to take one step back on the previous message,
// because the "batch" might not have been consumed in its entirety.
// The client will then be able to discard the first messages if needed.
entryId = msgId.getEntryId() - 1;
}
synchronized (ledger) {
// Create a new non-durable cursor only for the first consumer that connects
Subscription subscription = subscriptions.computeIfAbsent(subscriptionName, name -> {
MessageIdImpl msgId = startMessageId != null ? (MessageIdImpl) startMessageId
: (MessageIdImpl) MessageId.latest;

long ledgerId = msgId.getLedgerId();
long entryId = msgId.getEntryId();
if (ledgerId >= 0
&& msgId instanceof BatchMessageIdImpl) {
// When the start message is relative to a batch, we need to take one step back on the previous message,
// because the "batch" might not have been consumed in its entirety.
// The client will then be able to discard the first messages if needed.
entryId = msgId.getEntryId() - 1;
}

Position startPosition = new PositionImpl(ledgerId, entryId);
ManagedCursor cursor = null;
try {
cursor = ledger.newNonDurableCursor(startPosition, subscriptionName);
} catch (ManagedLedgerException e) {
subscriptionFuture.completeExceptionally(e);
}
Position startPosition = new PositionImpl(ledgerId, entryId);
ManagedCursor cursor = null;
try {
cursor = ledger.newNonDurableCursor(startPosition, subscriptionName);
} catch (ManagedLedgerException e) {
subscriptionFuture.completeExceptionally(e);
}

return new PersistentSubscription(this, subscriptionName, cursor, false);
});
return new PersistentSubscription(this, subscriptionName, cursor, false);
});

if (!subscriptionFuture.isDone()) {
if (startMessageRollbackDurationSec > 0) {
long timestamp = System.currentTimeMillis() - TimeUnit.SECONDS.toMillis(startMessageRollbackDurationSec);
subscription.resetCursor(timestamp).handle((s, ex) -> {
if (ex != null) {
log.warn("[{}] Failed to reset cursor {} position at timestamp {}", topic, subscriptionName,
startMessageRollbackDurationSec);
}
if (!subscriptionFuture.isDone()) {
if (startMessageRollbackDurationSec > 0) {
long timestamp = System.currentTimeMillis() - TimeUnit.SECONDS.toMillis(startMessageRollbackDurationSec);
subscription.resetCursor(timestamp).handle((s, ex) -> {
if (ex != null) {
log.warn("[{}] Failed to reset cursor {} position at timestamp {}", topic, subscriptionName,
startMessageRollbackDurationSec);
}
subscriptionFuture.complete(subscription);
return null;
});
} else {
subscriptionFuture.complete(subscription);
return null;
});
}
} else {
subscriptionFuture.complete(subscription);
// failed to initialize managed-cursor: clean up created subscription
subscriptions.remove(subscriptionName);
}
} else {
// failed to initialize managed-cursor: clean up created subscription
subscriptions.remove(subscriptionName);
}

return subscriptionFuture;
Expand Down