[GitHub] [hadoop] Jing9 commented on a diff in pull request #5203: HDFS-16867. Exiting Mover due to an exception in MoverMetrics.create

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

Jing9 commented on code in PR #5203:
URL: https://github.com/apache/hadoop/pull/5203#discussion_r1052583684


##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/NameNodeConnector.java:
##########
@@ -161,6 +162,7 @@ public static void checkOtherInstanceRunning(boolean toCheck) {
   private final Path idPath;
   private OutputStream out;
   private final List<Path> targetPaths;
+  private final MoverMetrics moverMetrics;

Review Comment:
   NameNodeConnector will also be used by Balancer, while MoverMetrics is only used by Mover. So not sure if placing MoverMetrics directly in NameNodeConnector is a good way from the semantic perspective.



##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/mover/Mover.java:
##########
@@ -160,7 +160,7 @@ Collections.<String> emptySet(), movedWinWidth, moverThreads, 0,
         BlockStoragePolicySuite.ID_BIT_LENGTH];
     this.excludedPinnedBlocks = excludedPinnedBlocks;
     this.nnc = nnc;
-    this.metrics = MoverMetrics.create(this);

Review Comment:
   If the main issue if the potential naming conflict caused by multiple mover instances, can we track the existing MoverMetrics instances and their NNC mappings at the class level (i.e. through a class static field) to avoid the duplication?



##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/mover/Mover.java:
##########
@@ -160,7 +160,7 @@ Collections.<String> emptySet(), movedWinWidth, moverThreads, 0,
         BlockStoragePolicySuite.ID_BIT_LENGTH];
     this.excludedPinnedBlocks = excludedPinnedBlocks;
     this.nnc = nnc;
-    this.metrics = MoverMetrics.create(this);
+    this.metrics = nnc.getMoverMetrics();

Review Comment:
   We also need to add some UTs to reproduce the issue (without your fix) and validate the fix.



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