[pulsar] 01/04: Fix deadlock that occurred during topic ownership check (#8406)

[rx...@apache.org]

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rxl pushed a commit to branch branch-2.6
in repository https://gitbox.apache.org/repos/asf/pulsar.git

commit fe3a258c3a696683009d8ff2771a3e4df757ea7f
Author: Masahiro Sakamoto <ma...@yahoo-corp.jp>
AuthorDate: Fri Oct 30 04:00:37 2020 +0900

    Fix deadlock that occurred during topic ownership check (#8406)
    
    
    (cherry picked from commit f96bc6305f54cd1845af64707ba4b94a7e9d861a)
---
 .../apache/pulsar/broker/namespace/NamespaceService.java   | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/pulsar-broker/src/main/java/org/apache/pulsar/broker/namespace/NamespaceService.java b/pulsar-broker/src/main/java/org/apache/pulsar/broker/namespace/NamespaceService.java
index f2995ee..a1acf28 100644
--- a/pulsar-broker/src/main/java/org/apache/pulsar/broker/namespace/NamespaceService.java
+++ b/pulsar-broker/src/main/java/org/apache/pulsar/broker/namespace/NamespaceService.java
@@ -931,7 +931,19 @@ public class NamespaceService {
         if (bundle.isPresent()) {
             return ownershipCache.getOwnedBundle(bundle.get()) != null;
         } else {
-            return ownershipCache.getOwnedBundle(getBundle(topicName)) != null;
+            // Calling `getBundle(TopicName)` here can cause a deadlock.
+            // cf. https://github.com/apache/pulsar/pull/4190
+            //
+            // This method returns false once if the bundle metadata is not cached, but gets the metadata asynchronously
+            // to cache it. Otherwise, the clients will never be able to connect to the topic due to ServiceUnitNotReadyException.
+            // cf. https://github.com/apache/pulsar/pull/5919
+            getBundleAsync(topicName).thenAccept(bundle2 -> {
+                LOG.info("Succeeded in getting bundle {} for topic - [{}]", bundle2, topicName);
+            }).exceptionally(ex -> {
+                LOG.warn("Failed to get bundle for topic - [{}] {}", topicName, ex.getMessage());
+                return null;
+            });
+            return false;
         }
     }