Fix: deadlock while closing non-shared consumer (apache#1591)

* Fix: deadlock while closing non-shared consumer

* removing consumer async cause failure in unsubscribe. so, remove subscription async from topic

pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentSubscription.java

@@ -153,7 +153,11 @@ public synchronized void removeConsumer(Consumer consumer) throws BrokerServiceE
             if (!cursor.isDurable()) {
                 // If cursor is not durable, we need to clean up the subscription as well
                 close();
-                topic.removeSubscription(subName);
+                // when topic closes: it iterates through concurrent-subscription map to close each subscription. so,
+                // topic.remove again try to access same map which creates deadlock. so, execute it in different thread.
+                topic.getBrokerService().pulsar().getExecutor().submit(() ->{
+                    topic.removeSubscription(subName);
+                });
             }
         }