HBASE-15529 Override needBalance in StochasticLoadBalancer (Guanghao Zhang)

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

@@ -68,7 +68,7 @@ import com.google.common.collect.Sets;
  *
  */
 public abstract class BaseLoadBalancer implements LoadBalancer {
-  private static final int MIN_SERVER_BALANCE = 2;
+  protected static final int MIN_SERVER_BALANCE = 2;
   private volatile boolean stopped = false;
 
   private static final List<HRegionInfo> EMPTY_REGION_LIST = new ArrayList<HRegionInfo>(0);

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

@@ -42,6 +42,7 @@ import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.master.MasterServices;
 import org.apache.hadoop.hbase.master.RegionPlan;
+import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.Action;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.Action.Type;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.AssignRegionAction;
@@ -107,6 +108,8 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
   protected static final String KEEP_REGION_LOADS =
       "hbase.master.balancer.stochastic.numRegionLoadsToRemember";
   private static final String TABLE_FUNCTION_SEP = "_";
+  protected static final String MIN_COST_NEED_BALANCE_KEY =
+      "hbase.master.balancer.stochastic.minCostNeedBalance";
 
   private static final Random RANDOM = new Random(System.currentTimeMillis());
   private static final Log LOG = LogFactory.getLog(StochasticLoadBalancer.class);
@@ -118,6 +121,7 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
   private int stepsPerRegion = 800;
   private long maxRunningTime = 30 * 1000 * 1; // 30 seconds.
   private int numRegionLoadsToRemember = 15;
+  private float minCostNeedBalance = 0.05f;
 
   private CandidateGenerator[] candidateGenerators;
   private CostFromRegionLoadFunction[] regionLoadFunctions;
@@ -163,6 +167,8 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     numRegionLoadsToRemember = conf.getInt(KEEP_REGION_LOADS, numRegionLoadsToRemember);
     isByTable = conf.getBoolean(HConstants.HBASE_MASTER_LOADBALANCE_BYTABLE, isByTable);
 
+    minCostNeedBalance = conf.getFloat(MIN_COST_NEED_BALANCE_KEY, minCostNeedBalance);
+
     if (localityCandidateGenerator == null) {
       localityCandidateGenerator = new LocalityBasedCandidateGenerator(services);
     }
@@ -257,6 +263,41 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     return false;
   }
 
+  @Override
+  protected boolean needsBalance(Cluster cluster) {
+    ClusterLoadState cs = new ClusterLoadState(cluster.clusterState);
+    if (cs.getNumServers() < MIN_SERVER_BALANCE) {
+      if (LOG.isDebugEnabled()) {
+        LOG.debug("Not running balancer because only " + cs.getNumServers()
+            + " active regionserver(s)");
+      }
+      return false;
+    }
+    if (areSomeRegionReplicasColocated(cluster)) {
+      return true;
+    }
+
+    double total = 0.0;
+    float sumMultiplier = 0.0f;
+    for (CostFunction c : costFunctions) {
+      float multiplier = c.getMultiplier();
+      if (multiplier <= 0) {
+        continue;
+      }
+      sumMultiplier += multiplier;
+      total += c.cost() * multiplier;
+    }
+
+    if (total <= 0 || sumMultiplier <= 0
+        || (sumMultiplier > 0 && (total / sumMultiplier) < minCostNeedBalance)) {
+      LOG.info("Skipping load balancing because balanced cluster; " + "total cost is " + total
+          + ", sum multiplier is " + sumMultiplier + " min cost which need balance is "
+          + minCostNeedBalance);
+      return false;
+    }
+    return true;
+  }
+
   @Override
   public synchronized List<RegionPlan> balanceCluster(TableName tableName, Map<ServerName,
     List<HRegionInfo>> clusterState) {
@@ -298,19 +339,21 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     // Keep track of servers to iterate through them.
     Cluster cluster = new Cluster(clusterState, loads, finder, rackManager);
 
-    if (!needsBalance(cluster)) {
-      return null;
-    }
-
     long startTime = EnvironmentEdgeManager.currentTime();
 
     initCosts(cluster);
 
+    if (!needsBalance(cluster)) {
+      return null;
+    }
+
     double currentCost = computeCost(cluster, Double.MAX_VALUE);
     curOverallCost = currentCost;
     for (int i = 0; i < this.curFunctionCosts.length; i++) {
       curFunctionCosts[i] = tempFunctionCosts[i];
     }
+    LOG.info("start StochasticLoadBalancer.balaner, initCost=" + currentCost + ", functionCost="
+        + functionCost());
 
     double initCost = currentCost;
     double newCost = currentCost;
@@ -407,6 +450,18 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     }
   }
 
+  private String functionCost() {
+    StringBuilder builder = new StringBuilder();
+    for (CostFunction c:costFunctions) {
+      builder.append(c.getClass().getSimpleName());
+      builder.append(" : (");
+      builder.append(c.getMultiplier());
+      builder.append(", ");
+      builder.append(c.cost());
+      builder.append("); ");
+    }
+    return builder.toString();
+  }
 
   /**
    * Create all of the RegionPlan's needed to move from the initial cluster state to the desired

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

@@ -70,6 +70,7 @@ public class BalancerTestBase {
     conf.setFloat("hbase.master.balancer.stochastic.maxMovePercent", 0.75f);
     conf.setFloat("hbase.regions.slop", 0.0f);
     conf.setFloat("hbase.master.balancer.stochastic.localityCost", 0);
+    conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 0.0f);
     loadBalancer = new StochasticLoadBalancer();
     loadBalancer.setConf(conf);
   }

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

@@ -93,6 +93,20 @@ public class TestStochasticLoadBalancer extends BalancerTestBase {
     }
   }
 
+  @Test
+  public void testNeedBalance() {
+    conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 1.0f);
+    loadBalancer.setConf(conf);
+    for (int[] mockCluster : clusterStateMocks) {
+      Map<ServerName, List<HRegionInfo>> servers = mockClusterServers(mockCluster);
+      List<RegionPlan> plans = loadBalancer.balanceCluster(servers);
+      assertNull(plans);
+    }
+    // reset config
+    conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 0.0f);
+    loadBalancer.setConf(conf);
+  }
+
   /**
    * Test the load balancing algorithm.
    *

hbase-server/src/test/java/org/apache/hadoop/hbase/master/balancer/TestStochasticLoadBalancer2.java

@@ -49,6 +49,7 @@ public class TestStochasticLoadBalancer2 extends BalancerTestBase {
     conf.setLong(StochasticLoadBalancer.MAX_STEPS_KEY, 2000000L);
     conf.setLong("hbase.master.balancer.stochastic.maxRunningTime", 90 * 1000); // 90 sec
     conf.setFloat("hbase.master.balancer.stochastic.localityCost", 0);
+    conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 0.05f);
     loadBalancer.setConf(conf);
     int numNodes = 1000;
     int numRegions = 20 * numNodes; // 20 * replication regions per RS
@@ -56,6 +57,9 @@ public class TestStochasticLoadBalancer2 extends BalancerTestBase {
     int numTables = 100;
     int replication = 3;
     testWithCluster(numNodes, numRegions, numRegionsPerServer, replication, numTables, true, true);
+    // reset config
+    conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 0.0f);
+    loadBalancer.setConf(conf);
   }
 
   @Test (timeout = 800000)