[GitHub] [helix] chenboat commented on a change in pull request #378: Make the reservoir used in ZkClientPathMonitor metric configurable.

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

chenboat commented on a change in pull request #378: Make the reservoir used in ZkClientPathMonitor metric configurable.
URL: https://github.com/apache/helix/pull/378#discussion_r311361633
 
 

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 File path: helix-core/src/main/java/org/apache/helix/monitoring/mbeans/ZkClientMonitor.java
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 @@ -81,8 +90,14 @@ public ZkClientMonitor(String monitorType, String monitorKey, String monitorInst
     if (zkEventThread != null) {
       _zkEventThreadMetric = new ZkThreadMetric(zkEventThread);
     }
+    if (mbeanReservoir == null) {
+      _mbeanReservoir =  new SlidingTimeWindowArrayReservoir(DEFAULT_RESET_INTERVAL_MS, TimeUnit.MILLISECONDS);
 
 Review comment:
   Per this doc: https://metrics.dropwizard.io/4.0.0/manual/core.html, 
   "10K measurements / sec with reservoir storing time of 1 minute will take 10000 * 60 * 128 / 8 = 9600000 bytes ~ **9 megabytes**"
   
   So with the current default of 1 hour, it will be about 540 M bytes. One of our moderately loaded prod server heapdump shows a single Reservoir which uses ~200M of memory. We can choose either make either Reservoir or Interval time configurable. I chose the former so that the client can even configure an alternative reservoir type.  
   

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