HBASE-28774: Protect hbase:meta from any hotspotting regions by balancing them to different region servers

hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/BalancerClusterState.java

@@ -109,6 +109,7 @@ class BalancerClusterState {
 
   int numMovedRegions = 0; // num moved regions from the initial configuration
   Map<ServerName, List<RegionInfo>> clusterState;
+  Map<ServerName, List<RegionInfo>> allTablesClusterState;
 
   private final RackManager rackManager;
   // Maps region -> rackIndex -> locality of region on rack

hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java

@@ -590,6 +590,13 @@ protected abstract List<RegionPlan> balanceTable(TableName tableName,
     preBalanceCluster(Map<TableName, Map<ServerName, List<RegionInfo>>> loadOfAllTable) {
   }
 
+  /**
+   * Called after executing balanceCluster. The sub classes could override this method to
+   * do some cleanup work.
+   */
+  protected void completeBalancerCosts(Map<TableName, Map<ServerName, List<RegionInfo>>> loadOfAllTable) {
+  }
+
   /**
    * Perform the major balance operation for cluster, will invoke
    * {@link #balanceTable(TableName, Map)} to do actual balance.
@@ -605,20 +612,24 @@ protected abstract List<RegionPlan> balanceTable(TableName tableName,
   public final List<RegionPlan>
     balanceCluster(Map<TableName, Map<ServerName, List<RegionInfo>>> loadOfAllTable) {
     preBalanceCluster(loadOfAllTable);
+    List<RegionPlan> result;
     if (isByTable) {
-      List<RegionPlan> result = new ArrayList<>();
-      loadOfAllTable.forEach((tableName, loadOfOneTable) -> {
+        result = new ArrayList<>();
+        loadOfAllTable.forEach((tableName, loadOfOneTable) -> {
         LOG.info("Start Generate Balance plan for table: " + tableName);
         List<RegionPlan> partialPlans = balanceTable(tableName, loadOfOneTable);
         if (partialPlans != null) {
           result.addAll(partialPlans);
         }
       });
-      return result;
     } else {
       LOG.debug("Start Generate Balance plan for cluster.");
-      return balanceTable(HConstants.ENSEMBLE_TABLE_NAME, toEnsumbleTableLoad(loadOfAllTable));
+      result = balanceTable(HConstants.ENSEMBLE_TABLE_NAME, toEnsumbleTableLoad(loadOfAllTable));
     }
+    //run at cluster
+    //addall to partialplans
+    completeBalancerCosts(loadOfAllTable);
+    return result;
   }
 
   @Override

hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/CostFunction.java

@@ -113,4 +113,12 @@ protected static double scale(double min, double max, double value) {
 
     return Math.max(0d, Math.min(1d, (value - min) / (max - min)));
   }
+
+  /**
+   * Called once per LB invocation to give the cost function to carry out any
+   * state clean up.
+   */
+  void complete(BalancerClusterState cluster) {
+    this.cluster = cluster;
+  }
 }

hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/MutuallyExclusiveTablesCostFunction.java

@@ -0,0 +1,113 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.master.balancer;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.yetus.audience.InterfaceAudience;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Ensure Tables are mutually exclusive on an RS
+ * for example: META and SYSTEM.CATALOG can be mutually exclusive Tables
+ * on same RS
+ */
+@InterfaceAudience.Private
+public class MutuallyExclusiveTablesCostFunction extends CostFunction {
+  public static final String MUTUALLY_EXCLUSIVE_TABLES_KEY =
+    "hbase.master.balancer.stochastic.mutuallyExclusiveTables";
+  public static final String MUTUALLY_EXCLUSIVE_TABLES_COST_KEY =
+    "hbase.master.balancer.stochastic.mutuallyExclusiveTablesCost";
+  public static final float DEFAULT_MUTUALLY_EXCLUSIVE_TABLES_COST = 10000;
+  private Set<String> mutuallyExclusiveTables = Collections.emptySet();
+  private static final Map<ServerName, Set<String>> sharedState = new HashMap<>();
+
+
+  public MutuallyExclusiveTablesCostFunction(Configuration conf) {
+    this.setMultiplier(
+      conf.getFloat(MUTUALLY_EXCLUSIVE_TABLES_COST_KEY, DEFAULT_MUTUALLY_EXCLUSIVE_TABLES_COST));
+    initializeMutuallyExclusiveTables(conf);
+  }
+
+  private void initializeMutuallyExclusiveTables(Configuration conf) {
+    String[] tables = conf.getStrings(MUTUALLY_EXCLUSIVE_TABLES_KEY);
+    if (tables != null && tables.length > 0) {
+      this.mutuallyExclusiveTables = new HashSet<>(Arrays.asList(tables));
+    }
+  }
+
+  @Override void prepare(BalancerClusterState cluster) {
+    super.prepare(cluster);
+    // Register the current table's regions in the shared state
+    Map<ServerName, List<RegionInfo>> clusterState = this.cluster.clusterState;
+
+    for (Map.Entry<ServerName, List<RegionInfo>> entry : clusterState.entrySet()) {
+      Set<String> tablesOnServer = sharedState.computeIfAbsent(entry.getKey(), k -> new HashSet<>());
+
+      for (RegionInfo regionInfo : entry.getValue()) {
+        String tableName = regionInfo.getTable().getNameAsString();
+        if (mutuallyExclusiveTables.contains(tableName)) {
+          tablesOnServer.add(tableName);
+        }
+      }
+    }
+  }
+
+  @Override void complete(BalancerClusterState cluster) {
+    super.complete(cluster);
+    // Clear the shared state
+    sharedState.clear();
+  }
+
+  @Override protected double cost() {
+    double totalCost = 0;
+
+    Map<ServerName, List<RegionInfo>> clusterState = this.cluster.clusterState;
+
+    for (Map.Entry<ServerName, List<RegionInfo>> entry : clusterState.entrySet()) {
+      List<RegionInfo> regions = entry.getValue();
+      Set<String> exclusiveTablesOnServer = new HashSet<>();
+      if(totalCost == 1)
+        break;
+      for (RegionInfo regionInfo : regions) {
+        String tableName = regionInfo.getTable().getNameAsString();
+        if (mutuallyExclusiveTables.contains(tableName)) {
+          // If its already seen table, continue
+          if (exclusiveTablesOnServer.contains(tableName)) {
+            continue;
+          }
+          exclusiveTablesOnServer.add(tableName);
+          if (exclusiveTablesOnServer.size() > 1) {
+            totalCost = 1;
+            break;
+          }
+        }
+      }
+    }
+
+    return totalCost;
+  }
+}

hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java

@@ -180,6 +180,25 @@ public StochasticLoadBalancer(MetricsStochasticBalancer metricsStochasticBalance
     super(metricsStochasticBalancer);
   }
 
+  @Override protected void completeBalancerCosts(
+    Map<TableName, Map<ServerName, List<RegionInfo>>> loadOfAllTable) {
+    if (isByTable) {
+      loadOfAllTable.forEach((tableName, loadOfOneTable) -> {
+        LOG.info("Complete Balancer plan for table: " + tableName);
+        BalancerClusterState cluster =
+          new BalancerClusterState(loadOfOneTable, loads, null, rackManager,
+            regionCacheRatioOnOldServerMap);
+        completeCosts(cluster);
+      });
+    } else {
+      LOG.debug("Complete Balancer plan for cluster.");
+      BalancerClusterState cluster =
+        new BalancerClusterState(toEnsumbleTableLoad(loadOfAllTable), loads, null, rackManager,
+          regionCacheRatioOnOldServerMap);
+      completeCosts(cluster);
+    }
+  }
+
   private static CostFunction createCostFunction(Class<? extends CostFunction> clazz,
     Configuration conf) {
     try {
@@ -754,6 +773,14 @@ void initCosts(BalancerClusterState cluster) {
     }
   }
 
+  @RestrictedApi(explanation = "Should only be called in tests", link = "",
+    allowedOnPath = ".*(/src/test/.*|StochasticLoadBalancer).java")
+  void completeCosts(BalancerClusterState cluster) {
+    for (CostFunction c : costFunctions) {
+      c.complete(cluster);
+    }
+  }
+
   /**
    * Update both the costs of costfunctions and the weights of candidate generators
    */

hbase-balancer/src/test/java/org/apache/hadoop/hbase/master/balancer/TestStochasticLoadBalancer.java

@@ -17,6 +17,8 @@
  */
 package org.apache.hadoop.hbase.master.balancer;
 
+import static org.apache.hadoop.hbase.master.balancer.MutuallyExclusiveTablesCostFunction.DEFAULT_MUTUALLY_EXCLUSIVE_TABLES_COST;
+import static org.apache.hadoop.hbase.master.balancer.MutuallyExclusiveTablesCostFunction.MUTUALLY_EXCLUSIVE_TABLES_KEY;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -45,6 +47,7 @@
 import org.apache.hadoop.hbase.Size;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.client.RegionInfoBuilder;
 import org.apache.hadoop.hbase.master.RegionPlan;
 import org.apache.hadoop.hbase.testclassification.MasterTests;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
@@ -401,6 +404,43 @@ public void testLocalityCost() throws Exception {
     }
   }
 
+  @Test
+  public void testMutuallyExclusiveTablesOnDifferentServers() throws Exception
+  {
+    conf.setStrings(MUTUALLY_EXCLUSIVE_TABLES_KEY, "table1", "table2");
+    loadBalancer.onConfigurationChange(conf);
+    Map<ServerName, List<RegionInfo>> clusterState = new HashMap<>();
+    ServerName host1 = ServerName.valueOf("host1", 1000, 1000);
+    ServerName host2 = ServerName.valueOf("host2", 1000, 1000);
+    RegionInfo region1 = RegionInfoBuilder.newBuilder(TableName.valueOf("table1")).build();
+    RegionInfo region2 = RegionInfoBuilder.newBuilder(TableName.valueOf("table2")).build();
+    clusterState.put(host1 , Arrays.asList(region1));
+    clusterState.put(host2 , Arrays.asList(region2));
+    CostFunction costFunction = new MutuallyExclusiveTablesCostFunction(conf);
+    costFunction.prepare(new BalancerClusterState(clusterState, null, null, null));
+    double cost = costFunction.cost();
+    assertEquals(0.0, cost, 0.001);
+  }
+
+  @Test
+  public void testMutuallyExclusiveTablesOnSameServer() throws Exception
+  {
+    conf.setStrings(MUTUALLY_EXCLUSIVE_TABLES_KEY, "table1", "table2");
+    loadBalancer.onConfigurationChange(conf);
+    Map<ServerName, List<RegionInfo>> clusterState = new HashMap<>();
+    ServerName host1 = ServerName.valueOf("host1", 1000, 1000);
+    RegionInfo region1 = RegionInfoBuilder.newBuilder(TableName.valueOf("table1")).build();
+    RegionInfo region2 = RegionInfoBuilder.newBuilder(TableName.valueOf("table2")).build();
+    List<RegionInfo> regions = new ArrayList<>();
+    regions.add(region1);
+    regions.add(region2);
+    clusterState.put(host1 , regions);
+    CostFunction costFunction = new MutuallyExclusiveTablesCostFunction(conf);
+    costFunction.prepare(new BalancerClusterState(clusterState, null, null, null));
+    double cost = costFunction.cost();
+    assertEquals(1, cost, 0.001);
+  }
+
   @Test
   public void testMoveCostMultiplier() throws Exception {
     Configuration conf = HBaseConfiguration.create();