diff --git a/src/main/java/com/alibaba/druid/pool/ha/MultiDataSource.java b/src/main/java/com/alibaba/druid/pool/ha/MultiDataSource.java
index a751474041..d1c465ae67 100644
--- a/src/main/java/com/alibaba/druid/pool/ha/MultiDataSource.java
+++ b/src/main/java/com/alibaba/druid/pool/ha/MultiDataSource.java
@@ -471,10 +471,26 @@ public class MultiDataSource extends DataSourceAdapter implements MultiDataSourc
     public long getRetryGetConnectionCount() {
         return retryGetConnectionCount.get();
     }
+    
+    public void incrementRetryGetConnectionCount() {
+        retryGetConnectionCount.incrementAndGet();
+    }
+    
+    public Lock getLock() {
+        return lock;
+    }
+    
+    public Condition getNotFail() {
+        return notFail;
+    }
 
     public long getBusySkipCount() {
         return busySkipCount.get();
     }
+    
+    public void incrementBusySkipCount() {
+        busySkipCount.incrementAndGet();
+    }
 
     public String[] getDataSourceNames() {
         return this.dataSources.keySet().toArray(new String[this.dataSources.size()]);
diff --git a/src/main/java/com/alibaba/druid/pool/ha/balance/WeightBalancer.java b/src/main/java/com/alibaba/druid/pool/ha/balance/WeightBalancer.java
index 36eeeebfcc..eac6e071b4 100644
--- a/src/main/java/com/alibaba/druid/pool/ha/balance/WeightBalancer.java
+++ b/src/main/java/com/alibaba/druid/pool/ha/balance/WeightBalancer.java
@@ -1,6 +1,100 @@
 package com.alibaba.druid.pool.ha.balance;
 
+import java.sql.SQLException;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
 
-public class WeightBalancer {
+import com.alibaba.druid.pool.ha.DataSourceHolder;
+import com.alibaba.druid.pool.ha.MultiConnectionHolder;
+import com.alibaba.druid.pool.ha.MultiDataSource;
+import com.alibaba.druid.pool.ha.MultiDataSourceConnection;
+
+public class WeightBalancer implements Balancer {
+
+    @Override
+    public MultiConnectionHolder getConnection(MultiDataSourceConnection connectionProxy, String sql)
+                                                                                                     throws SQLException {
+        MultiDataSource haDataSource = connectionProxy.getHaDataSource();
+        
+        long maxWaitMillis = haDataSource.getMaxWaitMillis();
+        
+        long startNano = -1;
+        if (maxWaitMillis > 0) {
+            startNano = System.nanoTime();
+        }
+
+        DataSourceHolder dataSource = null;
+
+        final int MAX_RETRY = 10;
+        for (int i = 0; i < MAX_RETRY; ++i) {
+            int randomNumber = haDataSource.produceRandomNumber();
+            DataSourceHolder first = null;
+
+            boolean needRetry = false;
+            for (DataSourceHolder item : haDataSource.getDataSources().values()) {
+                if (first == null) {
+                    first = item;
+                }
+                if (randomNumber >= item.getWeightRegionBegin() && randomNumber < item.getWeightRegionEnd()) {
+                    if (!item.isEnable()) {
+                        needRetry = true;
+                        break;
+                    }
+
+                    if (item.getDataSource().isBusy()) {
+                        haDataSource.incrementBusySkipCount();
+                        needRetry = true;
+                        break;
+                    }
+
+                    dataSource = item;
+                }
+            }
+
+            if (needRetry) {
+                haDataSource.incrementRetryGetConnectionCount();
+                continue;
+            }
+
+            if (dataSource == null) {
+                dataSource = first;
+            }
+
+            if (dataSource == null && i != MAX_RETRY - 1) {
+                Lock lock = haDataSource.getLock();
+                Condition notFail = haDataSource.getNotFail();
+                lock.lock();
+                try {
+                    if (haDataSource.getEnabledDataSourceCount() == 0) {
+                        try {
+                            if (maxWaitMillis > 0) {
+                                long nano = System.nanoTime() - startNano;
+                                long restNano = maxWaitMillis * 1000 * 1000 - nano;
+                                if (restNano > 0) {
+                                    notFail.awaitNanos(restNano);
+                                } else {
+                                    break;
+                                }
+                            } else {
+                                notFail.await();
+                            }
+                            continue;
+                        } catch (InterruptedException e) {
+                            throw new SQLException("interrupted", e);
+                        }
+                    }
+                } finally {
+                    lock.unlock();
+                }
+            }
+            break;
+        }
+
+        if (dataSource == null) {
+            throw new SQLException("cannot get connection. enabledDataSourceCount " + haDataSource.getEnabledDataSourceCount());
+        }
+
+        return dataSource.getConnection();
+    }
 
 }