Dynamic Config

server/src/main/java/io/druid/server/coordinator/CoordinatorDynamicConfig.java

@@ -31,6 +31,7 @@ public class CoordinatorDynamicConfig
   private final int maxSegmentsToMove;
   private final int replicantLifetime;
   private final int replicationThrottleLimit;
+  private final int costBalancerThreads;
   private final boolean emitBalancingStats;
 
   @JsonCreator
@@ -41,6 +42,7 @@ public class CoordinatorDynamicConfig
       @JsonProperty("maxSegmentsToMove") int maxSegmentsToMove,
       @JsonProperty("replicantLifetime") int replicantLifetime,
       @JsonProperty("replicationThrottleLimit") int replicationThrottleLimit,
+      @JsonProperty("costBalancerThreads") int costBalancerThreads,
       @JsonProperty("emitBalancingStats") boolean emitBalancingStats
   )
   {
@@ -51,6 +53,7 @@ public class CoordinatorDynamicConfig
     this.replicantLifetime = replicantLifetime;
     this.replicationThrottleLimit = replicationThrottleLimit;
     this.emitBalancingStats = emitBalancingStats;
+    this.costBalancerThreads = costBalancerThreads;
   }
 
   @JsonProperty
@@ -95,6 +98,12 @@ public class CoordinatorDynamicConfig
     return replicationThrottleLimit;
   }
 
+  @JsonProperty
+  public int getCostBalancerThreads()
+  {
+    return costBalancerThreads;
+  }
+
   public static class Builder
   {
     private long millisToWaitBeforeDeleting;
@@ -104,10 +113,11 @@ public class CoordinatorDynamicConfig
     private int replicantLifetime;
     private int replicationThrottleLimit;
     private boolean emitBalancingStats;
+    private int costBalancerThreads;
 
     public Builder()
     {
-      this(15 * 60 * 1000L, 100000000L, Integer.MAX_VALUE, 5, 15, 10, false);
+      this(15 * 60 * 1000L, 100000000L, Integer.MAX_VALUE, 5, 15, 10, 1, false);
     }
 
     private Builder(
@@ -117,6 +127,7 @@ public class CoordinatorDynamicConfig
         int maxSegmentsToMove,
         int replicantLifetime,
         int replicationThrottleLimit,
+        int costBalancerThreads,
         boolean emitBalancingStats
     )
     {
@@ -127,6 +138,7 @@ public class CoordinatorDynamicConfig
       this.replicantLifetime = replicantLifetime;
       this.replicationThrottleLimit = replicationThrottleLimit;
       this.emitBalancingStats = emitBalancingStats;
+      this.costBalancerThreads = costBalancerThreads;
     }
 
     public Builder withMillisToWaitBeforeDeleting(long millisToWaitBeforeDeleting)
@@ -165,6 +177,12 @@ public class CoordinatorDynamicConfig
       return this;
     }
 
+    public Builder withCostBalancerThreads(int costBalancerThreads)
+    {
+      this.costBalancerThreads = costBalancerThreads;
+      return this;
+    }
+
     public CoordinatorDynamicConfig build()
     {
       return new CoordinatorDynamicConfig(
@@ -174,6 +192,7 @@ public class CoordinatorDynamicConfig
           maxSegmentsToMove,
           replicantLifetime,
           replicationThrottleLimit,
+          costBalancerThreads,
           emitBalancingStats
       );
     }

server/src/main/java/io/druid/server/coordinator/DruidCoordinator.java

@@ -745,7 +745,7 @@ public class DruidCoordinator
         else if (RANDOM.equals(config.getCoordinatorBalancerStrategy()))
           factory= new RandomBalancerStrategyFactory();
         else if (COST_MULTI.equals(config.getCoordinatorBalancerStrategy()))
-          factory = new CostBalancerMultithreadStrategyFactory(config.getCostBalancerStrategyThreadCount());
+          factory = new CostBalancerMultithreadStrategyFactory(getDynamicConfigs().getCostBalancerThreads());
 
         // Do coordinator stuff.
         DruidCoordinatorRuntimeParams params =

server/src/main/java/io/druid/server/coordinator/DruidCoordinatorConfig.java

@@ -46,10 +46,6 @@ public abstract class DruidCoordinatorConfig
   @Default("cost")
   public abstract String getCoordinatorBalancerStrategy();
 
-  @Config("druid.coordinator.cost.balancer.threads")
-  @Default("4")
-  public abstract int getCostBalancerStrategyThreadCount();
-
   @Config("druid.coordinator.merge.on")
   public boolean isMergeSegments()
   {

server/src/test/java/io/druid/server/coordinator/DruidCoordinatorTest.java

@@ -102,11 +102,6 @@ public class DruidCoordinatorTest
             return null;
           }
 
-          @Override
-          public int getCostBalancerStrategyThreadCount()
-          {
-            return 1;
-          }
         },
         new ZkPathsConfig(){