[GitHub] sijie closed pull request #1558: [dlog] Issue 1544: ConcurrentModificationException with nonblocking logReader.readNext(true)

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

sijie closed pull request #1558: [dlog] Issue 1544: ConcurrentModificationException with nonblocking logReader.readNext(true)
URL: https://github.com/apache/bookkeeper/pull/1558
 
 
   

This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:

As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):

diff --git a/stream/distributedlog/core/src/main/java/org/apache/distributedlog/impl/ZKLogSegmentMetadataStore.java b/stream/distributedlog/core/src/main/java/org/apache/distributedlog/impl/ZKLogSegmentMetadataStore.java
index d78b4550f7..f688f445db 100644
--- a/stream/distributedlog/core/src/main/java/org/apache/distributedlog/impl/ZKLogSegmentMetadataStore.java
+++ b/stream/distributedlog/core/src/main/java/org/apache/distributedlog/impl/ZKLogSegmentMetadataStore.java
@@ -476,8 +476,12 @@ void notifyLogStreamDeleted(String logSegmentsPath,
             return;
         }
         this.submitTask(logSegmentsPath, () -> {
-            for (LogSegmentNamesListener listener : listeners.keySet()) {
-                listener.onLogStreamDeleted();
+            // the listener map might be updated in different threads (e.g. unregisterLogSegmentListener)
+            // so access it under a synchronization block
+            synchronized (listeners) {
+                for (LogSegmentNamesListener listener : listeners.keySet()) {
+                    listener.onLogStreamDeleted();
+                }
             }
         });
 
@@ -490,8 +494,12 @@ void notifyLogSegmentsUpdated(String logSegmentsPath,
             return;
         }
         this.submitTask(logSegmentsPath, () -> {
-            for (VersionedLogSegmentNamesListener listener : listeners.values()) {
-                listener.onSegmentsUpdated(segments);
+            // the listener map might be updated in different threads (e.g. unregisterLogSegmentListener)
+            // so access it under a synchronization block
+            synchronized (listeners) {
+                for (VersionedLogSegmentNamesListener listener : listeners.values()) {
+                    listener.onSegmentsUpdated(segments);
+                }
             }
         });
     }


 

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