diff --git a/src/main/java/com/corundumstudio/socketio/BroadcastOperations.java b/src/main/java/com/corundumstudio/socketio/BroadcastOperations.java
index f0189f6..0de6348 100644
--- a/src/main/java/com/corundumstudio/socketio/BroadcastOperations.java
+++ b/src/main/java/com/corundumstudio/socketio/BroadcastOperations.java
@@ -15,10 +15,56 @@
  */
 package com.corundumstudio.socketio;
 
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+
 import com.corundumstudio.socketio.parser.Packet;
 
 public class BroadcastOperations implements ClientOperations {
 
+    private class BroadcastAckCallback extends AckCallback {
+
+        final AtomicBoolean loopFinished = new AtomicBoolean();
+        final AtomicInteger counter = new AtomicInteger();
+        final AtomicBoolean timeoutExecuted = new AtomicBoolean();
+        final AtomicBoolean successExecuted = new AtomicBoolean();
+        final AckCallback ackCallback;
+
+        public BroadcastAckCallback(AckCallback ackCallback) {
+            this.ackCallback = ackCallback;
+        }
+
+        @Override
+        public void onSuccess() {
+            counter.getAndDecrement();
+            executeSuccess();
+        }
+
+        private void executeSuccess() {
+            if (loopFinished.get() && counter.get() == 0 && successExecuted.compareAndSet(false, true)) {
+                ackCallback.onSuccess();
+            }
+        }
+
+        @Override
+        public void onTimeout() {
+            // execute onTimeout once
+            if (timeoutExecuted.compareAndSet(false, true)) {
+                ackCallback.onTimeout();
+            }
+        }
+
+        void incrementCounter() {
+            counter.getAndIncrement();
+        }
+
+        void loopFinished() {
+            loopFinished.set(true);
+            executeSuccess();
+        }
+
+    }
+
     private final Iterable<SocketIOClient> clients;
 
     public BroadcastOperations(Iterable<SocketIOClient> clients) {
@@ -35,9 +81,12 @@ public class BroadcastOperations implements ClientOperations {
 
     @Override
     public void sendMessage(String message, AckCallback ackCallback) {
+        BroadcastAckCallback clientCallback = new BroadcastAckCallback(ackCallback);
         for (SocketIOClient client : clients) {
-            client.sendMessage(message, ackCallback);
+            clientCallback.incrementCounter();
+            client.sendMessage(message, clientCallback);
         }
+        clientCallback.loopFinished();
     }
 
     @Override
@@ -49,9 +98,12 @@ public class BroadcastOperations implements ClientOperations {
 
     @Override
     public void sendJsonObject(Object object, AckCallback ackCallback) {
+        BroadcastAckCallback clientCallback = new BroadcastAckCallback(ackCallback);
         for (SocketIOClient client : clients) {
-            client.sendJsonObject(object, ackCallback);
+            clientCallback.incrementCounter();
+            client.sendJsonObject(object, clientCallback);
         }
+        clientCallback.loopFinished();
     }
 
     @Override
@@ -63,9 +115,12 @@ public class BroadcastOperations implements ClientOperations {
 
     @Override
     public void send(Packet packet, AckCallback ackCallback) {
+        BroadcastAckCallback clientCallback = new BroadcastAckCallback(ackCallback);
         for (SocketIOClient client : clients) {
+            clientCallback.incrementCounter();
             client.send(packet, ackCallback);
         }
+        clientCallback.loopFinished();
     }
 
     @Override
@@ -84,9 +139,12 @@ public class BroadcastOperations implements ClientOperations {
 
     @Override
     public void sendEvent(String name, Object data, AckCallback ackCallback) {
+        BroadcastAckCallback clientCallback = new BroadcastAckCallback(ackCallback);
         for (SocketIOClient client : clients) {
+            clientCallback.incrementCounter();
             client.sendEvent(name, data, ackCallback);
         }
+        clientCallback.loopFinished();
     }
 
 }
diff --git a/src/main/java/com/corundumstudio/socketio/HeartbeatHandler.java b/src/main/java/com/corundumstudio/socketio/HeartbeatHandler.java
index b54dfc5..c2a7fd5 100644
--- a/src/main/java/com/corundumstudio/socketio/HeartbeatHandler.java
+++ b/src/main/java/com/corundumstudio/socketio/HeartbeatHandler.java
@@ -44,17 +44,20 @@ public class HeartbeatHandler implements Disconnectable {
             return;
         }
 
-        scheduler.cancel(new SchedulerKey(Type.HEARBEAT_TIMEOUT, client.getSessionId()));
+        final SchedulerKey key = new SchedulerKey(Type.HEARBEAT_TIMEOUT, client.getSessionId());
+        // cancel heartbeat check because the client answered
+        scheduler.cancel(key);
         scheduler.schedule(new Runnable() {
             public void run() {
                 client.send(new Packet(PacketType.HEARTBEAT));
-                scheduleClientHeartbeatCheck(client);
+                scheduleClientHeartbeatCheck(client, key);
             }
         }, configuration.getHeartbeatInterval(), TimeUnit.SECONDS);
     }
 
-    private void scheduleClientHeartbeatCheck(final BaseClient client) {
-        SchedulerKey key = new SchedulerKey(Type.HEARBEAT_TIMEOUT, client.getSessionId());
+    private void scheduleClientHeartbeatCheck(final BaseClient client, SchedulerKey key) {
+        // cancel previous heartbeat check
+        scheduler.cancel(key);
         scheduler.schedule(key, new Runnable() {
             public void run() {
                 client.disconnect();
diff --git a/src/main/java/com/corundumstudio/socketio/scheduler/CancelableScheduler.java b/src/main/java/com/corundumstudio/socketio/scheduler/CancelableScheduler.java
index ede3d42..71c68c8 100644
--- a/src/main/java/com/corundumstudio/socketio/scheduler/CancelableScheduler.java
+++ b/src/main/java/com/corundumstudio/socketio/scheduler/CancelableScheduler.java
@@ -24,7 +24,7 @@ import java.util.concurrent.TimeUnit;
 
 public class CancelableScheduler {
 
-    private final Map<Object, Future<?>> scheduledFutures = new ConcurrentHashMap<Object, Future<?>>();
+    private final Map<SchedulerKey, Future<?>> scheduledFutures = new ConcurrentHashMap<SchedulerKey, Future<?>>();
     private final ScheduledExecutorService executorService;
 
     public CancelableScheduler(int threadPoolSize) {