remove output for assign_add_variable_op.

src/TensorFlowNET.Core/Eager/EagerTensor.Creation.cs

@@ -62,7 +62,8 @@ namespace Tensorflow.Eager
             GarbageCollector.Decrease(tfe_tensor_handle);
             GarbageCollector.Decrease(EagerTensorHandle);
 
-            /*c_api.TF_DeleteTensor(_handle);
+            /*print($"deleting DeleteTensorHandle {Id} {_handle.ToString("x16")}");
+            c_api.TF_DeleteTensor(_handle);
             print($"deleting DeleteTensorHandle {Id} {tfe_tensor_handle.ToString("x16")}");
             c_api.TFE_DeleteTensorHandle(tfe_tensor_handle);
             print($"deleting DeleteEagerTensor {Id} {EagerTensorHandle.ToString("x16")}");

src/TensorFlowNET.Core/Operations/gen_resource_variable_ops.cs

@@ -56,7 +56,6 @@ namespace Tensorflow
         {
             if (tf.context.executing_eagerly())
             {
-                var results = new[] { new EagerTensor() };
                 Status status = c_api.TFE_FastPathExecute(tf.context, tf.context.device_name,
                     "AssignAddVariableOp", name,
                     new IntPtr[]
@@ -64,9 +63,9 @@ namespace Tensorflow
                         resource as EagerTensor,
                         value as EagerTensor
                     }, 2, null,
-                    results.Select(x => x.EagerTensorHandle).ToArray(), results.Length);
+                    null, 0);
                 status.Check(true);
-                return results[0].Resolve();
+                return null;
             }
 
             return null;
@@ -76,7 +75,6 @@ namespace Tensorflow
         {
             if (tf.context.executing_eagerly())
             {
-                var results = new EagerTensor[0];
                 Status status = c_api.TFE_FastPathExecute(tf.context, tf.context.device_name,
                     "AssignVariableOp", name,
                     new IntPtr[]
@@ -84,7 +82,7 @@ namespace Tensorflow
                         resource as EagerTensor,
                         value as EagerTensor
                     }, 2, null,
-                    results.Select(x => x.EagerTensorHandle).ToArray(), results.Length);
+                    null, 0);
                 status.Check(true);
                 return null;
             }

src/TensorFlowNET.Core/System/GarbageCollector.cs

@@ -29,6 +29,9 @@ namespace Tensorflow
 
         public static void Increase(IntPtr handle, GCItemType type)
         {
+            if (handle == IntPtr.Zero)
+                return;
+
             if (container.ContainsKey(handle))
             {
                 container[handle].RefCounter++;
@@ -51,11 +54,8 @@ namespace Tensorflow
 
         public static void Decrease(IntPtr handle)
         {
-            lock (locker)
-            {
-                if (container.ContainsKey(handle))
-                    container[handle].RefCounter--;
-            }
+            if (handle != IntPtr.Zero && container.ContainsKey(handle))
+                container[handle].RefCounter--;
         }
 
         private static void Recycle()

src/TensorFlowNET.Core/Training/gen_training_ops.py.cs → src/TensorFlowNET.Core/Training/gen_training_ops.cs

@@ -65,7 +65,6 @@ namespace Tensorflow
         {
             if (tf.context.executing_eagerly())
             {
-                var results = new[] { new EagerTensor() };
                 Status status = c_api.TFE_FastPathExecute(tf.context, tf.context.device_name,
                     "ResourceApplyGradientDescent", name, new IntPtr[]
                     {
@@ -74,9 +73,9 @@ namespace Tensorflow
                         delta
                     }, 3, 
                     op => wrap_tfe_src.SetOpAttrs(op, "use_locking", use_locking),
-                    results.Select(x => x.EagerTensorHandle).ToArray(), results.Length);
+                    null, 0);
                 status.Check(true);
-                return results[0].Resolve();
+                return null;
             }
 
             var _op = _op_def_lib._apply_op_helper("ResourceApplyGradientDescent", name, new