fix

Author: JiayiFeng

paddle/fluid/pybind/tensor_py.h

@@ -107,7 +107,7 @@ T TensorGetElement(const framework::Tensor &self, size_t offset) {
     return self.data<T>()[offset];
   } else {
     std::shared_ptr<framework::Tensor> dst(new framework::Tensor);
-    framework::TensorCopy(self, platform::CPUPlace(), dst.get());
+    framework::TensorCopySync(self, platform::CPUPlace(), dst.get());
     return dst->data<T>()[offset];
   }
 }
@@ -117,9 +117,9 @@ template <typename T>
 void TensorSetElement(framework::Tensor *self, size_t offset, T elem) {
   if (platform::is_gpu_place(self->place())) {
     std::shared_ptr<framework::Tensor> dst(new framework::Tensor);
-    framework::TensorCopy(*self, platform::CPUPlace(), dst.get());
+    framework::TensorCopySync(*self, platform::CPUPlace(), dst.get());
     dst->data<T>()[offset] = elem;
-    framework::TensorCopy(*dst.get(), self->place(), self);
+    framework::TensorCopySync(*dst.get(), self->place(), self);
 
   } else if (platform::is_cpu_place(self->place())) {
     self->data<T>()[offset] = elem;