HDDS-507. EventQueue should be shutdown on SCM shutdown. Contributed by Xiaoyu Yao.

(cherry picked from commit 236d16e3a5611b8ca4f80cb7e8ffd63f167db8e0)

hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/server/StorageContainerManager.java

@@ -759,6 +759,13 @@ public final class StorageContainerManager extends ServiceRuntimeInfoImpl
     }
 
     unregisterMXBean();
+    // Event queue must be stopped before the DB store is closed at the end.
+    try {
+      LOG.info("Stopping SCM Event Queue.");
+      eventQueue.close();
+    } catch (Exception ex) {
+      LOG.error("SCM Event Queue stop failed", ex);
+    }
     IOUtils.cleanupWithLogger(LOG, scmContainerManager);
   }