[GitHub] [hadoop] xkrogen commented on a diff in pull request #5215: HADOOP-18567. LogThrottlingHelper: the dependent recorder is not triggered correctly

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

xkrogen commented on code in PR #5215:
URL: https://github.com/apache/hadoop/pull/5215#discussion_r1047905288


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hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/log/LogThrottlingHelper.java:
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@@ -262,8 +263,15 @@ public LogAction record(String recorderName, long currentTimeMs,
     if (primaryRecorderName.equals(recorderName) &&
         currentTimeMs - minLogPeriodMs >= lastLogTimestampMs) {
       lastLogTimestampMs = currentTimeMs;
-      for (LoggingAction log : currentLogs.values()) {
-        log.setShouldLog();
+      for (Iterator<LoggingAction> it = currentLogs.values().iterator(); it
+          .hasNext();) {
+        LoggingAction log = it.next();
+        if (log.hasLogged()) {
+          // Make sure the dependent recorders will be triggered the next time
+          it.remove();
+        } else {
+          log.setShouldLog();
+        }
       }

Review Comment:
   This does solve the issue but it feels a bit awkward/confusing to me. Having no entry in `currentLogs` is supposed to indicate that this `recoderName` has never been seen before.
   
   What do you think about this instead:
   ```suggestion
         currentLogs.replaceAll((k, log) -> {
           LoggingAction newLog = log;
           if (log.hasLogged()) {
             // create a fresh log since the old one has already been logged
             newLog = new LoggingAction(log.getValueCount());
           }
           newLog.setShouldLog();
           return newLog;
         });
   ```
   
   I feel it's a bit more explicit/clear about what we're achieving. WDYT?
   
   (note that this also requires creating a new method in `LoggingAction` to expose the value count like `private int getValueCount() { return stats.length; }`)



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