lordcheng10 opened a new pull request, #18633:
URL: https://github.com/apache/pulsar/pull/18633
### Motivation
For exclusive subscriptions, if two consumers are created repeatedly, the
second consumer will block.
**Steps to reproduce:**
Start the following program twice. When starting the second time, the
subscribe method will block and will not throw an exception:
ConsumerBusyException: Exclusive consumer is already connected
```
String topic = "test1";
List<Integer> partitions = new ArrayList<>();
for (int i = 0; i < 120; i++) {
partitions.add(i);
}
List<String> realTopics = partitions.stream()
.map(idx -> topic + "-partition-" + idx)
.collect(Collectors.toList());
Map<String, Object> consumerParams = Collections.emptyMap();
System.out.println("begin subscribe " + LocalTime.now());
Consumer<byte[]> consumer;
try {
consumer = client.newConsumer()
.loadConf(consumerParams)
.topics(realTopics)
.subscriptionName(testName)
.subscriptionType(SubscriptionType.Exclusive)
.subscriptionInitialPosition(SubscriptionInitialPosition.Latest)
.subscribe();
} catch (Exception ex) {
System.out.println("after subscribe " + LocalTime.now() );
}
```
The reasons are as follows:
When the 1121 line of code is executed, the consumers list may be empty,
which will cause the subscribeFuture to fail to complete, and eventually cause
the subscribe method to block forever and not throw an exception:
https://github.com/apache/pulsar/blob/355ba6002fc33b2716f59ca5d3a4fac667ecf3e1/pulsar-client/src/main/java/org/apache/pulsar/client/impl/MultiTopicsConsumerImpl.java#L1121-L1144
### Modifications
Make subscribeFuture complete when the filtered consumer collection is empty：
```
List<ConsumerImpl> filterConsumers =
consumers.values().stream().filter(consumer1 -> {
String consumerTopicName = consumer1.getTopic();
if
(TopicName.get(consumerTopicName).getPartitionedTopicName()
.equals(TopicName.get(topicName).getPartitionedTopicName())) {
toCloseNum.incrementAndGet();
return true;
} else {
return false;
}
}).collect(Collectors.toList());
if (filterConsumers.isEmpty()) {
subscribeFuture.completeExceptionally(error);
return;
}
```
### Documentation
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