HBASE-3373 Allow regions to be load-balanced by table

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1227873 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/hadoop/hbase/master/AssignmentManager.java

@@ -49,6 +49,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.Chore;
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.HRegionInfo;
+import org.apache.hadoop.hbase.HServerLoad;
 import org.apache.hadoop.hbase.NotServingRegionException;
 import org.apache.hadoop.hbase.Server;
 import org.apache.hadoop.hbase.ServerName;
@@ -2781,6 +2782,55 @@ public class AssignmentManager extends ZooKeeperListener {
     }
   }
 
+  /**
+   * This is an EXPENSIVE clone.  Cloning though is the safest thing to do.
+   * Can't let out original since it can change and at least the loadbalancer
+   * wants to iterate this exported list.  We need to synchronize on regions
+   * since all access to this.servers is under a lock on this.regions.
+   * 
+   * @return A clone of current assignments by table.
+   */
+  Map<String, Map<ServerName, List<HRegionInfo>>> getAssignmentsByTable() {
+    Map<String, Map<ServerName, List<HRegionInfo>>> result = null;
+    synchronized (this.regions) {
+      result = new HashMap<String, Map<ServerName,List<HRegionInfo>>>();
+      if (!this.master.getConfiguration().
+          getBoolean("hbase.master.loadbalance.bytable", true)) {
+        result.put("ensemble", getAssignments());
+      } else {
+        for (Map.Entry<ServerName, Set<HRegionInfo>> e: this.servers.entrySet()) {
+          for (HRegionInfo hri : e.getValue()) {
+            if (hri.isMetaRegion() || hri.isRootRegion()) continue;
+            String tablename = hri.getTableNameAsString();
+            Map<ServerName, List<HRegionInfo>> svrToRegions = result.get(tablename);
+            if (svrToRegions == null) {
+              svrToRegions = new HashMap<ServerName, List<HRegionInfo>>(this.servers.size());
+              result.put(tablename, svrToRegions);
+            }
+            List<HRegionInfo> regions = null;
+            if (!svrToRegions.containsKey(e.getKey())) {
+              regions = new ArrayList<HRegionInfo>();
+              svrToRegions.put(e.getKey(), regions);
+            } else {
+              regions = svrToRegions.get(e.getKey());
+            }
+            regions.add(hri);
+          }
+        }
+      }
+    }
+    Map<ServerName, HServerLoad> onlineSvrs = this.serverManager.getOnlineServers();
+    // Take care of servers w/o assignments.
+    for (Map<ServerName,List<HRegionInfo>> map : result.values()) {
+      for (Map.Entry<ServerName, HServerLoad> svrEntry: onlineSvrs.entrySet()) {
+        if (!map.containsKey(svrEntry.getKey())) {
+          map.put(svrEntry.getKey(), new ArrayList<HRegionInfo>());
+        }
+      }
+    }
+    return result;
+  }
+  
   /**
    * @return A clone of current assignments. Note, this is assignments only.
    * If a new server has come in and it has no regions, it will not be included

src/main/java/org/apache/hadoop/hbase/master/HMaster.java

@@ -945,16 +945,14 @@ implements HMasterInterface, HMasterRegionInterface, MasterServices, Server {
         }
       }
 
-      Map<ServerName, List<HRegionInfo>> assignments =
-        this.assignmentManager.getAssignments();
-      // Returned Map from AM does not include mention of servers w/o assignments.
-      for (Map.Entry<ServerName, HServerLoad> e:
-        this.serverManager.getOnlineServers().entrySet()) {
-        if (!assignments.containsKey(e.getKey())) {
-          assignments.put(e.getKey(), new ArrayList<HRegionInfo>());
-        }
+      Map<String, Map<ServerName, List<HRegionInfo>>> assignmentsByTable =
+        this.assignmentManager.getAssignmentsByTable();
+
+      List<RegionPlan> plans = new ArrayList<RegionPlan>();
+      for (Map<ServerName, List<HRegionInfo>> assignments : assignmentsByTable.values()) {
+        List<RegionPlan> partialPlans = this.balancer.balanceCluster(assignments);
+        if (partialPlans != null) plans.addAll(partialPlans);
       }
-      List<RegionPlan> plans = this.balancer.balanceCluster(assignments);
       int rpCount = 0;  // number of RegionPlans balanced so far
       long totalRegPlanExecTime = 0;
       balancerRan = plans != null;

src/test/java/org/apache/hadoop/hbase/TestRegionRebalancing.java

@@ -169,9 +169,16 @@ public class TestRegionRebalancing {
         LOG.debug(server.getServerName() + " Avg: " + avg + " actual: " + serverLoad);
         if (!(avg > 2.0 && serverLoad <= avgLoadPlusSlop
             && serverLoad >= avgLoadMinusSlop)) {
-          LOG.debug(server.getServerName() + " Isn't balanced!!! Avg: " + avg +
-              " actual: " + serverLoad + " slop: " + slop);
-          success = false;
+          for (HRegionInfo hri : server.getOnlineRegions()) {
+            if (hri.isMetaRegion() || hri.isRootRegion()) serverLoad--;
+            // LOG.debug(hri.getRegionNameAsString());
+          }
+          if (!(serverLoad <= avgLoadPlusSlop && serverLoad >= avgLoadMinusSlop)) {
+            LOG.debug(server.getServerName() + " Isn't balanced!!! Avg: " + avg +
+                " actual: " + serverLoad + " slop: " + slop);
+            success = false;            
+            break;
+          }
         }
       }