[GitHub] [helix] i3wangyi commented on a change in pull request #365: Fix RoutingTableProvider statePropagationLatency metric reporting bug

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

i3wangyi commented on a change in pull request #365: Fix RoutingTableProvider statePropagationLatency metric reporting bug
URL: https://github.com/apache/helix/pull/365#discussion_r308433322
 
 

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 File path: helix-core/src/main/java/org/apache/helix/spectator/RoutingTableProvider.java
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 @@ -558,23 +558,28 @@ protected void refresh(Map<String, Map<String, Map<String, CurrentState>>> curre
 
   private void resetRoutingTableAndNotify(long startTime, RoutingTable newRoutingTable) {
     _routingTableRef.set(newRoutingTable);
-    logger.info("Refresh the RoutingTable for cluster {}, takes {} ms.",
-        (_helixManager != null ? _helixManager.getClusterName() : null),
+    String clusterName = _helixManager != null ? _helixManager.getClusterName() : null;
+    logger.info("Refresh the RoutingTable for cluster {}, takes {} ms.", clusterName,
         (System.currentTimeMillis() - startTime));
-    notifyRoutingTableChange();
+
+    notifyRoutingTableChange(_helixManager != null ? _helixManager.getClusterName() : null);
 
     // Update timestamp for last refresh
     if (_isPeriodicRefreshEnabled) {
       _lastRefreshTimestamp = System.currentTimeMillis();
     }
   }
 
-  private void notifyRoutingTableChange() {
-    for (Map.Entry<RoutingTableChangeListener, ListenerContext> entry : _routingTableChangeListenerMap
-        .entrySet()) {
-      entry.getKey().onRoutingTableChange(new RoutingTableSnapshot(_routingTableRef.get()),
-          entry.getValue().getContext());
+  private void notifyRoutingTableChange(String clusterName) {
+    // This call back is called in the main event queue of RoutingTableProvider. We add log to record time spent
+    // here. Potentially, we should call this callback in a separate thread if this is a bottleneck.
+    long startTime = System.currentTimeMillis();
+    for (Map.Entry<RoutingTableChangeListener, ListenerContext> entry : _routingTableChangeListenerMap.entrySet()) {
 
 Review comment:
   Would it be clearer using 
   `_routingTableChangeListenerMap.entrySet().forEach((k, v) ->  k.onRoutingTableChange(...));`

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