From 36b4698cea9485f4d491612342b8c841e1c3db86 Mon Sep 17 00:00:00 2001
From: Bharath Vissapragada <bharathv@apache.org>
Date: Mon, 25 Jan 2021 12:20:37 -0800
Subject: [PATCH] HBASE-25528: Dedicated merge dispatch threadpool on master

Adds "hbase.master.executor.merge.dispatch.threads" and defaults to 2.

Also adds additional logging that includes the number of split plans
and merge plans computed for each normalizer run.
---
 .../java/org/apache/hadoop/hbase/HConstants.java    |  7 +++++++
 .../org/apache/hadoop/hbase/executor/EventType.java |  2 +-
 .../apache/hadoop/hbase/executor/ExecutorType.java  |  1 +
 .../org/apache/hadoop/hbase/master/HMaster.java     |  3 +++
 .../master/normalizer/SimpleRegionNormalizer.java   | 13 ++++++++++---
 5 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java b/hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java
index d31cadd8529..48fa00caaa1 100644
--- a/hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java
+++ b/hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java
@@ -1605,6 +1605,13 @@ public final class HConstants {
       "hbase.master.executor.serverops.threads";
   public static final int MASTER_SERVER_OPERATIONS_THREADS_DEFAULT = 5;
 
+  /**
+   * Number of threads used to dispatch merge operations to the regionservers.
+   */
+  public static final String MASTER_MERGE_DISPATCH_THREADS =
+      "hbase.master.executor.merge.dispatch.threads";
+  public static final int MASTER_MERGE_DISPATCH_THREADS_DEFAULT = 2;
+
   public static final String MASTER_META_SERVER_OPERATIONS_THREADS =
       "hbase.master.executor.meta.serverops.threads";
   public static final int MASTER_META_SERVER_OPERATIONS_THREADS_DEFAULT = 5;
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/EventType.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/EventType.java
index a67447940b9..600c96cc026 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/EventType.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/EventType.java
@@ -152,7 +152,7 @@ public enum EventType {
    * C_M_MERGE_REGION<br>
    * Client asking Master to merge regions.
    */
-  C_M_MERGE_REGION          (30, ExecutorType.MASTER_TABLE_OPERATIONS),
+  C_M_MERGE_REGION          (30, ExecutorType.MASTER_MERGE_OPERATIONS),
   /**
    * Messages originating from Client to Master.<br>
    * C_M_DELETE_TABLE<br>
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/ExecutorType.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/ExecutorType.java
index d06bd54484d..36958c518a6 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/ExecutorType.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/executor/ExecutorType.java
@@ -35,6 +35,7 @@ public enum ExecutorType {
   MASTER_META_SERVER_OPERATIONS (6),
   M_LOG_REPLAY_OPS           (7),
   MASTER_SNAPSHOT_OPERATIONS (8),
+  MASTER_MERGE_OPERATIONS    (9),
 
   // RegionServer executor services
   RS_OPEN_REGION             (20),
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
index 94f3bf2bfda..9911f014d63 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
@@ -1324,6 +1324,9 @@ public class HMaster extends HRegionServer implements MasterServices {
       HConstants.MASTER_LOG_REPLAY_OPS_THREADS, HConstants.MASTER_LOG_REPLAY_OPS_THREADS_DEFAULT));
     this.executorService.startExecutorService(ExecutorType.MASTER_SNAPSHOT_OPERATIONS, conf.getInt(
       SnapshotManager.SNAPSHOT_POOL_THREADS_KEY, SnapshotManager.SNAPSHOT_POOL_THREADS_DEFAULT));
+    this.executorService.startExecutorService(ExecutorType.MASTER_MERGE_OPERATIONS, conf.getInt(
+        HConstants.MASTER_MERGE_DISPATCH_THREADS,
+        HConstants.MASTER_MERGE_DISPATCH_THREADS_DEFAULT));
 
     // We depend on there being only one instance of this executor running
     // at a time. To do concurrency, would need fencing of enable/disable of
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/SimpleRegionNormalizer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/SimpleRegionNormalizer.java
index 61bc922c5ac..52455686895 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/SimpleRegionNormalizer.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/SimpleRegionNormalizer.java
@@ -209,14 +209,21 @@ class SimpleRegionNormalizer implements RegionNormalizer, ConfigurationObserver
       ctx.getTableRegions().size());
 
     final List<NormalizationPlan> plans = new ArrayList<>();
+    int splitPlansCount = 0;
     if (proceedWithSplitPlanning) {
-      plans.addAll(computeSplitNormalizationPlans(ctx));
+      List<NormalizationPlan> splitPlans = computeSplitNormalizationPlans(ctx);
+      splitPlansCount = splitPlans.size();
+      plans.addAll(splitPlans);
     }
+    int mergePlansCount = 0;
     if (proceedWithMergePlanning) {
-      plans.addAll(computeMergeNormalizationPlans(ctx));
+      List<NormalizationPlan> mergePlans = computeMergeNormalizationPlans(ctx);
+      mergePlansCount = mergePlans.size();
+      plans.addAll(mergePlans);
     }
 
-    LOG.debug("Computed {} normalization plans for table {}", plans.size(), table);
+    LOG.debug("Computed normalization plans for table {}. Total plans: {}, split plans: {}, " +
+        "merge plans: {}", table, plans.size(), splitPlansCount, mergePlansCount);
     return plans;
   }