[GitHub] [hadoop] goiri commented on a diff in pull request #5714: HDFS-17026. RBF: NamenodeHeartbeatService should update JMX report with configurable frequency

["goiri (via GitHub)" <gi...@apache.org>]

goiri commented on code in PR #5714:
URL: https://github.com/apache/hadoop/pull/5714#discussion_r1218675945


##########
hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/NamenodeHeartbeatService.java:
##########
@@ -348,44 +362,73 @@ private void updateJMXParameters(
       String address, NamenodeStatusReport report) {
     try {
       // TODO part of this should be moved to its own utility
-      String query = "Hadoop:service=NameNode,name=FSNamesystem*";
-      JSONArray aux = FederationUtil.getJmx(
-          query, address, connectionFactory, scheme);
-      if (aux != null) {
-        for (int i = 0; i < aux.length(); i++) {
-          JSONObject jsonObject = aux.getJSONObject(i);
-          String name = jsonObject.getString("name");
-          if (name.equals("Hadoop:service=NameNode,name=FSNamesystemState")) {
-            report.setDatanodeInfo(
-                jsonObject.getInt("NumLiveDataNodes"),
-                jsonObject.getInt("NumDeadDataNodes"),
-                jsonObject.getInt("NumStaleDataNodes"),
-                jsonObject.getInt("NumDecommissioningDataNodes"),
-                jsonObject.getInt("NumDecomLiveDataNodes"),
-                jsonObject.getInt("NumDecomDeadDataNodes"),
-                jsonObject.optInt("NumInMaintenanceLiveDataNodes"),
-                jsonObject.optInt("NumInMaintenanceDeadDataNodes"),
-                jsonObject.optInt("NumEnteringMaintenanceDataNodes"));
-          } else if (name.equals(
-              "Hadoop:service=NameNode,name=FSNamesystem")) {
-            report.setNamesystemInfo(
-                jsonObject.getLong("CapacityRemaining"),
-                jsonObject.getLong("CapacityTotal"),
-                jsonObject.getLong("FilesTotal"),
-                jsonObject.getLong("BlocksTotal"),
-                jsonObject.getLong("MissingBlocks"),
-                jsonObject.getLong("PendingReplicationBlocks"),
-                jsonObject.getLong("UnderReplicatedBlocks"),
-                jsonObject.getLong("PendingDeletionBlocks"),
-                jsonObject.optLong("ProvidedCapacityTotal"));
-          }
-        }
+      if (shouldUpdateJmx()) {
+        this.lastJmxUpdateAttempt = Time.monotonicNow();
+        String query = "Hadoop:service=NameNode,name=FSNamesystem*";
+        this.fsNamesystemMetrics = FederationUtil.getJmx(
+            query, address, connectionFactory, scheme);
       }
+      populateFsNamesystemMetrics(this.fsNamesystemMetrics, report);
     } catch (Exception e) {
       LOG.error("Cannot get stat from {} using JMX", getNamenodeDesc(), e);
     }
   }
 
+  /**
+   * Evaluates whether the JMX report should be refreshed by
+   * calling the Namenode, based on the following conditions:
+   * 1. JMX Updates must be enabled.
+   * 2. The last attempt to update JMX occurred before the
+   *    configured interval (if any).
+   */
+  private boolean shouldUpdateJmx() {
+    if (this.updateJmxIntervalMs < 0) {
+      return false;
+    }
+
+    return Time.monotonicNow() - this.lastJmxUpdateAttempt > this.updateJmxIntervalMs;
+  }
+
+  /**
+   * Populates FSNamesystem* metrics into report.
+   * @param aux FSNamesystem* metrics from namenode.
+   * @param report Namenode status report to update with JMX data.
+   * @throws JSONException When invalid JSONObject is found.
+   */
+  private void populateFsNamesystemMetrics(JSONArray aux, NamenodeStatusReport report)
+      throws JSONException {
+    if (aux != null) {

Review Comment:
   Do early exit in == null and reduce nesting.



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