diff --git a/csharp/Adapter/Microsoft.Spark.CSharp/Core/Accumulator.cs b/csharp/Adapter/Microsoft.Spark.CSharp/Core/Accumulator.cs
index 0d26b06..816002e 100644
--- a/csharp/Adapter/Microsoft.Spark.CSharp/Core/Accumulator.cs
+++ b/csharp/Adapter/Microsoft.Spark.CSharp/Core/Accumulator.cs
@@ -75,6 +75,19 @@ namespace Microsoft.Spark.CSharp.Core
             accumulatorRegistry[accumulatorId] = this;
         }
 
+        [OnDeserialized()]
+        internal void OnDeserializedMethod(System.Runtime.Serialization.StreamingContext context)
+        {
+            if (threadLocalAccumulatorRegistry == null)
+            {
+                threadLocalAccumulatorRegistry = new Dictionary<int, Accumulator>();
+            }
+            if (!threadLocalAccumulatorRegistry.ContainsKey(accumulatorId))
+            {
+                threadLocalAccumulatorRegistry[accumulatorId] = this;
+            }
+        }
+
         /// <summary>
         /// Gets or sets the value of the accumulator; only usable in driver program
         /// </summary>
@@ -119,20 +132,6 @@ namespace Microsoft.Spark.CSharp.Core
         /// <returns></returns>
         public static Accumulator<T> operator +(Accumulator<T> self, T term)
         {
-            if (self.isDriver) // this is in driver
-            {
-                if (!accumulatorRegistry.ContainsKey(self.accumulatorId))
-                {
-                    accumulatorRegistry[self.accumulatorId] = self;
-                }
-            }
-            else // this is in executor
-            {
-                if (!threadLocalAccumulatorRegistry.ContainsKey(self.accumulatorId))
-                {
-                    threadLocalAccumulatorRegistry[self.accumulatorId] = self;
-                }
-            }
             self.Add(term);
             return self;
         }
diff --git a/csharp/Samples/Microsoft.Spark.CSharp/SparkContextSamples.cs b/csharp/Samples/Microsoft.Spark.CSharp/SparkContextSamples.cs
index c60fcfb..2769134 100644
--- a/csharp/Samples/Microsoft.Spark.CSharp/SparkContextSamples.cs
+++ b/csharp/Samples/Microsoft.Spark.CSharp/SparkContextSamples.cs
@@ -64,14 +64,30 @@ namespace Microsoft.Spark.CSharp.Samples
         internal class AccumulatorHelper
         {
             private Accumulator<int> accumulator;
-            internal AccumulatorHelper(Accumulator<int> accumulator)
+            private bool async;
+            internal AccumulatorHelper(Accumulator<int> accumulator, bool async = false)
             {
                 this.accumulator = accumulator;
+                this.async = async;
             }
 
             internal void Execute(int input)
             {
-                accumulator += input;
+                if (async)
+                {
+                    // start new task
+                    var task = new Task(() =>
+                    {
+                        accumulator += input;
+                    });
+                    task.Start();
+                    task.Wait();
+                }
+                else
+                {
+                    accumulator += input;
+                }
+
             }
         }
 
@@ -79,14 +95,17 @@ namespace Microsoft.Spark.CSharp.Samples
         internal static void SparkContextAccumulatorSample()
         {
             var a = SparkCLRSamples.SparkContext.Accumulator<int>(100);
-            SparkCLRSamples.SparkContext.Parallelize(new[] { 1, 2, 3, 4 }, 3).Foreach(new AccumulatorHelper(a).Execute);
+            var b = SparkCLRSamples.SparkContext.Accumulator<int>(100);
 
-            Console.WriteLine("accumulator value: " + a.Value);
+            SparkCLRSamples.SparkContext.Parallelize(new[] { 1, 2, 3, 4 }, 3).Foreach(new AccumulatorHelper(a).Execute);
+            SparkCLRSamples.SparkContext.Parallelize(new[] { 1, 2, 3, 4 }, 3).Foreach(new AccumulatorHelper(b, true).Execute);
+            Console.WriteLine("accumulator value, a: {0}, b: {1}", a.Value, b.Value);
 
             if (SparkCLRSamples.Configuration.IsValidationEnabled)
             {
                 // The value is accumulated on the initial value of the Accumulator which is 100. 110 = 100 + 1 + 2 + 3 + 4
                 Assert.AreEqual(110, a.Value);
+                Assert.AreEqual(110, b.Value);
             }
         }