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https://issues.apache.org/jira/browse/HADOOP-18920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17772439#comment-17772439
 ] 

ASF GitHub Bot commented on HADOOP-18920:
-----------------------------------------

xinglin commented on code in PR #6146:
URL: https://github.com/apache/hadoop/pull/6146#discussion_r1348240387


##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java:
##########
@@ -568,29 +579,15 @@ public long getPurgeIntervalNanos() {
    * @param methodName - RPC Request method name
    * @param details - Processing Detail.
    *
-   * if this request took too much time relative to other requests
-   * we consider that as a slow RPC. 3 is a magic number that comes
-   * from 3 sigma deviation. A very simple explanation can be found
-   * by searching for 68-95-99.7 rule. We flag an RPC as slow RPC
-   * if and only if it falls above 99.7% of requests. We start this logic
-   * only once we have enough sample size.
+   * if this request took time exceed `logSlowRPCThresholdMs`
+   * we consider that as a slow RPC.
    */
   void logSlowRpcCalls(String methodName, Call call,
       ProcessingDetails details) {
-    final int deviation = 3;
-
-    // 1024 for minSampleSize just a guess 

> RPC Metrics : Optimize logic for log slow RPCs
> ----------------------------------------------
>
>                 Key: HADOOP-18920
>                 URL: https://issues.apache.org/jira/browse/HADOOP-18920
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Haiyang Hu
>            Assignee: Haiyang Hu
>            Priority: Major
>              Labels: pull-request-available
>
> HADOOP-12325 implement a capability where "slow" RPCs are logged in NN log.
> Current processing logic is the "slow" RPCs are to be those whose processing 
> time is outside 3 standard deviation.
> However, in practice it is found that many logs of slow rpc are currently 
> output, and sometimes RPCs with a processing time of 1ms are also declared as 
> slow, this is not in line with actual expectations.
> Therefore, consider optimize the logic conditions of slow RPC and add a 
> `logSlowRPCThresholdMs` variable to judge whether the current RPCas slow so 
> that the expected slow RPC log can be logger.
> for `logSlowRPCThresholdMs`, we can support dynamic refresh to facilitate 
> adjustments based on the actual operating conditions of the hdfs cluster.



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