[GitHub] [pulsar] rdhabalia commented on a change in pull request #5371: fix potential deadlock that can occur in addConsumer

[GitBox <gi...@apache.org>]

rdhabalia commented on a change in pull request #5371: fix potential deadlock that can occur in addConsumer
URL: https://github.com/apache/pulsar/pull/5371#discussion_r335720118
 
 

 ##########
 File path: pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentDispatcherMultipleConsumers.java
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 @@ -158,9 +158,13 @@ public synchronized void addConsumer(Consumer consumer) throws BrokerServiceExce
     private boolean isConsumersExceededOnTopic() {
         Policies policies;
         try {
+            // Use getDataIfPresent from zk cache to make the call non-blocking and prevent deadlocks in addConsumer
             policies = topic.getBrokerService().pulsar().getConfigurationCache().policiesCache()
-                    .get(AdminResource.path(POLICIES, TopicName.get(topic.getName()).getNamespace()))
-                    .orElseGet(() -> new Policies());
+                    .getDataIfPresent(AdminResource.path(POLICIES, TopicName.get(topic.getName()).getNamespace()));
+
+            if (policies == null) {
+                policies = new Policies();
 
 Review comment:
   We should just return false instead of creating empty object.

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