Add dygraph models

dygraph/mnist/README.md

+# MNIST
+当我们学习编程的时候，编写的第一个程序一般是实现打印"Hello World"。而机器学习（或深度学习）的入门教程，一般都是 MNIST 数据库上的手写识别问题。原因是手写识别属于典型的图像分类问题，比较简单，同时MNIST数据集也很完备。
+本页将介绍如何使用PaddlePaddle在DyGraph模式下实现MNIST，包括[安装](#installation)、[训练](#training-a-model)、[输出](#log)、[参数保存](#save)、[模型评估](#evaluation)。
+
+---
+## 内容
+- [安装](#installation)
+- [训练](#training-a-model)
+- [输出](#log)
+
+## 安装
+
+在当前目录下运行样例代码需要PadddlePaddle Fluid的v1.4.0或以上的版本。如果你的运行环境中的PaddlePaddle低于此版本，请根据安装文档中的说明来更新PaddlePaddle。
+
+## 训练
+教程中使用`paddle.dataset.mnist`数据集作为训练数据，可以通过如下的方式启动训练：
+```
+env CUDA_VISIBLE_DEVICES=0 python mnist_dygraph.py
+```
+
+## 输出
+执行训练开始后，将得到类似如下的输出。
+```
+Loss at epoch 0 step 0: [2.3043773]
+Loss at epoch 0 step 100: [0.20764539]
+Loss at epoch 0 step 200: [0.18648806]
+Loss at epoch 0 step 300: [0.10279777]
+Loss at epoch 0 step 400: [0.03940877]
+...
+```
+
+## 参数保存
+调用`fluid.dygraph.save_persistables()`接口可以把模型的参数进行保存。
+```python
+fluid.dygraph.save_persistables(mnist.state_dict(), "save_dir")
+```
+
+## 测试
+执行`mnist.eval()`可以切换至评估状态，即不更新只使用参数进行训练，通过这种方式进行测试或者评估。
+```python
+mnist.eval()
+```
+
+## 模型评估
+我们使用手写数据集中的一张图片来进行评估。为了区别训练模型，我们使用`with fluid.dygraph.guard()`来切换到一个新的参数空间，然后构建一个用于评估的网络`mnist_infer`，并通过`mnist_infer.load_dict()`来加载使用`fluid.dygraph.load_persistables`读取的参数。然后用`mnist_infer.eval()`切换到评估。
+```python
+with fluid.dygraph.guard():
+
+    mnist_infer = MNIST("mnist")
+    # load checkpoint
+    mnist_infer.load_dict(
+        fluid.dygraph.load_persistables("save_dir"))
+
+    # start evaluate mode
+    mnist_infer.eval()
+```
+如果无意外，将可以看到预测的结果：
+```text
+Inference result of image/infer_3.png is: 3
+```
+
+

dygraph/mnist/mnist_dygraph.py

+# Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import numpy as np
+from PIL import Image
+import os
+import paddle
+import paddle.fluid as fluid
+from paddle.fluid.optimizer import AdamOptimizer
+from paddle.fluid.dygraph.nn import Conv2D, Pool2D, FC
+from paddle.fluid.dygraph.base import to_variable
+
+
+class SimpleImgConvPool(fluid.dygraph.Layer):
+    def __init__(self,
+                 name_scope,
+                 num_channels,
+                 num_filters,
+                 filter_size,
+                 pool_size,
+                 pool_stride,
+                 pool_padding=0,
+                 pool_type='max',
+                 global_pooling=False,
+                 conv_stride=1,
+                 conv_padding=0,
+                 conv_dilation=1,
+                 conv_groups=1,
+                 act=None,
+                 use_cudnn=False,
+                 param_attr=None,
+                 bias_attr=None):
+        super(SimpleImgConvPool, self).__init__(name_scope)
+
+        self._conv2d = Conv2D(
+            self.full_name(),
+            num_channels=num_channels,
+            num_filters=num_filters,
+            filter_size=filter_size,
+            stride=conv_stride,
+            padding=conv_padding,
+            dilation=conv_dilation,
+            groups=conv_groups,
+            param_attr=None,
+            bias_attr=None,
+            use_cudnn=use_cudnn)
+
+        self._pool2d = Pool2D(
+            self.full_name(),
+            pool_size=pool_size,
+            pool_type=pool_type,
+            pool_stride=pool_stride,
+            pool_padding=pool_padding,
+            global_pooling=global_pooling,
+            use_cudnn=use_cudnn)
+
+    def forward(self, inputs):
+        x = self._conv2d(inputs)
+        x = self._pool2d(x)
+        return x
+
+
+class MNIST(fluid.dygraph.Layer):
+    def __init__(self, name_scope):
+        super(MNIST, self).__init__(name_scope)
+
+        self._simple_img_conv_pool_1 = SimpleImgConvPool(
+            self.full_name(), 1, 20, 5, 2, 2, act="relu")
+
+        self._simple_img_conv_pool_2 = SimpleImgConvPool(
+            self.full_name(), 20, 50, 5, 2, 2, act="relu")
+
+        pool_2_shape = 50 * 4 * 4
+        SIZE = 10
+        scale = (2.0 / (pool_2_shape**2 * SIZE))**0.5
+        self._fc = FC(self.full_name(),
+                      10,
+                      param_attr=fluid.param_attr.ParamAttr(
+                          initializer=fluid.initializer.NormalInitializer(
+                              loc=0.0, scale=scale)),
+                      act="softmax")
+
+    def forward(self, inputs, label=None):
+        x = self._simple_img_conv_pool_1(inputs)
+        x = self._simple_img_conv_pool_2(x)
+        x = self._fc(x)
+        if label is not None:
+            acc = fluid.layers.accuracy(input=x, label=label)
+            return x, acc
+        else:
+            return x
+
+
+def test_train(reader, model, batch_size):
+    acc_set = []
+    avg_loss_set = []
+    for batch_id, data in enumerate(reader()):
+        dy_x_data = np.array(
+            [x[0].reshape(1, 28, 28)
+             for x in data]).astype('float32')
+        y_data = np.array(
+            [x[1] for x in data]).astype('int64').reshape(batch_size, 1)
+
+        img = to_variable(dy_x_data)
+        label = to_variable(y_data)
+        label.stop_gradient = True
+        prediction, acc = model(img, label)
+        loss = fluid.layers.cross_entropy(input=prediction, label=label)
+        avg_loss = fluid.layers.mean(loss)
+        acc_set.append(float(acc.numpy()))
+        avg_loss_set.append(float(avg_loss.numpy()))
+
+        # get test acc and loss
+    acc_val_mean = np.array(acc_set).mean()
+    avg_loss_val_mean = np.array(avg_loss_set).mean()
+
+    return avg_loss_val_mean, acc_val_mean
+
+
+def train_mnist():
+    epoch_num = 5
+    BATCH_SIZE = 64
+    with fluid.dygraph.guard():
+
+        mnist = MNIST("mnist")
+        adam = AdamOptimizer(learning_rate=0.001)
+        train_reader = paddle.batch(
+            paddle.dataset.mnist.train(), batch_size=BATCH_SIZE, drop_last=True)
+        test_reader = paddle.batch(
+            paddle.dataset.mnist.test(), batch_size=BATCH_SIZE, drop_last=True)
+        for epoch in range(epoch_num):
+            for batch_id, data in enumerate(train_reader()):
+                dy_x_data = np.array(
+                    [x[0].reshape(1, 28, 28)
+                     for x in data]).astype('float32')
+                y_data = np.array(
+                    [x[1] for x in data]).astype('int64').reshape(BATCH_SIZE, 1)
+
+                img = to_variable(dy_x_data)
+                label = to_variable(y_data)
+                label.stop_gradient = True
+
+                cost, acc = mnist(img, label)
+
+                loss = fluid.layers.cross_entropy(cost, label)
+                avg_loss = fluid.layers.mean(loss)
+                avg_loss.backward()
+                adam.minimize(avg_loss)
+                # save checkpoint
+                mnist.clear_gradients()
+                if batch_id % 100 == 0:
+                    print("Loss at epoch {} step {}: {:}".format(epoch, batch_id, avg_loss.numpy()))
+
+            mnist.eval()
+            test_cost, test_acc = test_train(test_reader, mnist, BATCH_SIZE)
+            mnist.train()
+            print("Loss at epoch {} , Test avg_loss is: {}, acc is: {}".format(epoch, test_cost, test_acc))
+
+        fluid.dygraph.save_persistables(mnist.state_dict(), "save_dir")
+        print("checkpoint saved")
+
+    with fluid.dygraph.guard():
+
+        mnist_infer = MNIST("mnist")
+        # load checkpoint
+        mnist_infer.load_dict(
+            fluid.dygraph.load_persistables("save_dir"))
+        print("checkpoint loaded")
+
+        # start evaluate mode
+        mnist_infer.eval()
+
+        def load_image(file):
+            im = Image.open(file).convert('L')
+            im = im.resize((28, 28), Image.ANTIALIAS)
+            im = np.array(im).reshape(1, 1, 28, 28).astype(np.float32)
+            im = im / 255.0 * 2.0 - 1.0
+            return im
+
+        cur_dir = os.path.dirname(os.path.realpath(__file__))
+        tensor_img = load_image(cur_dir + '/image/infer_3.png')
+
+        results = mnist_infer(to_variable(tensor_img))
+        lab = np.argsort(results.numpy())
+        print("Inference result of image/infer_3.png is: %d" % lab[0][-1])
+
+
+if __name__ == '__main__':
+    train_mnist()

dygraph/resnet/README.md

+DyGraph模式下Residual Network实现
+========
+
+简介
+--------
+Residual Network（ResNet）是常用的图像分类模型。我们实现了在paddlepaddle的DyGraph模式下相应的实现。可以对比原先静态图下实现（[Residual Network](https://github.com/PaddlePaddle/models/tree/develop/PaddleCV/image_classification/models)）来了解paddle中DyGraph模式。
+运行本目录下的程序示例需要使用PaddlePaddle develop最新版本。如果您的PaddlePaddle安装版本低于此要求，请按照[安装文档](http://www.paddlepaddle.org/docs/develop/documentation/zh/build_and_install/pip_install_cn.html)中的说明更新PaddlePaddle安装版本。
+
+
+## 代码结构
+```
+└── train.py     # 训练脚本。
+```
+
+## 使用的数据
+
+教程中使用`paddle.dataset.flowers`数据集作为训练数据，该数据集通过`paddle.dataset`模块自动下载到本地。
+
+## 训练测试Residual Network
+
+在GPU单卡上训练Residual Network:
+
+```
+env CUDA_VISIBLE_DEVICES=0 python train.py
+```
+
+这里`CUDA_VISIBLE_DEVICES=0`表示是执行在0号设备卡上，请根据自身情况修改这个参数。
+
+## 输出
+执行训练开始后，将得到类似如下的输出。每一轮`batch`训练将会打印当前epoch、step以及loss值。当前默认执行`epoch=10`, `batch_size=8`。您可以调整参数以得到更好的训练效果，同时也意味着消耗更多的内存（显存）以及需要花费更长的时间。
+```text
+epoch id: 0, batch step: 0, loss: 4.951202
+epoch id: 0, batch step: 1, loss: 5.268410
+epoch id: 0, batch step: 2, loss: 5.123999
+```

dygraph/resnet/train.py

+# Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import numpy as np
+
+import paddle
+import paddle.fluid as fluid
+from paddle.fluid.layer_helper import LayerHelper
+from paddle.fluid.dygraph.nn import Conv2D, Pool2D, BatchNorm, FC
+from paddle.fluid.dygraph.base import to_variable
+
+batch_size = 8
+epoch = 10
+
+
+def optimizer_setting():
+    return fluid.optimizer.SGD(learning_rate=0.01)
+
+
+class ConvBNLayer(fluid.dygraph.Layer):
+    def __init__(self,
+                 name_scope,
+                 num_channels,
+                 num_filters,
+                 filter_size,
+                 stride=1,
+                 groups=1,
+                 act=None):
+        super(ConvBNLayer, self).__init__(name_scope)
+
+        self._conv = Conv2D(
+            self.full_name(),
+            num_channels=num_channels,
+            num_filters=num_filters,
+            filter_size=filter_size,
+            stride=stride,
+            padding=(filter_size - 1) // 2,
+            groups=groups,
+            act=None,
+            bias_attr=None)
+
+        self._batch_norm = BatchNorm(self.full_name(), num_filters, act=act)
+
+    def forward(self, inputs):
+        y = self._conv(inputs)
+        y = self._batch_norm(y)
+
+        return y
+
+
+class BottleneckBlock(fluid.dygraph.Layer):
+    def __init__(self,
+                 name_scope,
+                 num_channels,
+                 num_filters,
+                 stride,
+                 shortcut=True):
+        super(BottleneckBlock, self).__init__(name_scope)
+
+        self.conv0 = ConvBNLayer(
+            self.full_name(),
+            num_channels=num_channels,
+            num_filters=num_filters,
+            filter_size=1,
+            act='relu')
+        self.conv1 = ConvBNLayer(
+            self.full_name(),
+            num_channels=num_filters,
+            num_filters=num_filters,
+            filter_size=3,
+            stride=stride,
+            act='relu')
+        self.conv2 = ConvBNLayer(
+            self.full_name(),
+            num_channels=num_filters,
+            num_filters=num_filters * 4,
+            filter_size=1,
+            act=None)
+
+        if not shortcut:
+            self.short = ConvBNLayer(
+                self.full_name(),
+                num_channels=num_channels,
+                num_filters=num_filters * 4,
+                filter_size=1,
+                stride=stride)
+
+        self.shortcut = shortcut
+
+        self._num_channels_out = num_filters * 4
+
+    def forward(self, inputs):
+        y = self.conv0(inputs)
+        conv1 = self.conv1(y)
+        conv2 = self.conv2(conv1)
+
+        if self.shortcut:
+            short = inputs
+        else:
+            short = self.short(inputs)
+
+        y = fluid.layers.elementwise_add(x=short, y=conv2)
+
+        layer_helper = LayerHelper(self.full_name(), act='relu')
+        return layer_helper.append_activation(y)
+
+
+class ResNet(fluid.dygraph.Layer):
+    def __init__(self, name_scope, layers=50, class_dim=102):
+        super(ResNet, self).__init__(name_scope)
+
+        self.layers = layers
+        supported_layers = [50, 101, 152]
+        assert layers in supported_layers, \
+            "supported layers are {} but input layer is {}".format(supported_layers, layers)
+
+        if layers == 50:
+            depth = [3, 4, 6, 3]
+        elif layers == 101:
+            depth = [3, 4, 23, 3]
+        elif layers == 152:
+            depth = [3, 8, 36, 3]
+        num_filters = [64, 128, 256, 512]
+
+        self.conv = ConvBNLayer(
+            self.full_name(),
+            num_channels=3,
+            num_filters=64,
+            filter_size=7,
+            stride=2,
+            act='relu')
+        self.pool2d_max = Pool2D(
+            self.full_name(),
+            pool_size=3,
+            pool_stride=2,
+            pool_padding=1,
+            pool_type='max')
+
+        self.bottleneck_block_list = []
+        num_channels = 64
+        for block in range(len(depth)):
+            shortcut = False
+            for i in range(depth[block]):
+                bottleneck_block = self.add_sublayer(
+                    'bb_%d_%d' % (block, i),
+                    BottleneckBlock(
+                        self.full_name(),
+                        num_channels=num_channels,
+                        num_filters=num_filters[block],
+                        stride=2 if i == 0 and block != 0 else 1,
+                        shortcut=shortcut))
+                num_channels = bottleneck_block._num_channels_out
+                self.bottleneck_block_list.append(bottleneck_block)
+                shortcut = True
+
+        self.pool2d_avg = Pool2D(
+            self.full_name(), pool_size=7, pool_type='avg', global_pooling=True)
+
+        import math
+        stdv = 1.0 / math.sqrt(2048 * 1.0)
+
+        self.out = FC(self.full_name(),
+                      size=class_dim,
+                      act='softmax',
+                      param_attr=fluid.param_attr.ParamAttr(
+                          initializer=fluid.initializer.Uniform(-stdv, stdv)))
+
+    def forward(self, inputs):
+        y = self.conv(inputs)
+        y = self.pool2d_max(y)
+        for bottleneck_block in self.bottleneck_block_list:
+            y = bottleneck_block(y)
+        y = self.pool2d_avg(y)
+        y = self.out(y)
+        return y
+
+
+def train_resnet():
+    with fluid.dygraph.guard():
+        resnet = ResNet("resnet")
+        optimizer = optimizer_setting()
+        train_reader = paddle.batch(
+            paddle.dataset.flowers.train(),
+            batch_size=batch_size)
+
+        for eop in range(epoch):
+            for batch_id, data in enumerate(train_reader()):
+                dy_x_data = np.array(
+                    [x[0].reshape(3, 224, 224) for x in data]).astype('float32')
+                if len(np.array([x[1] for x in data]).astype('int64')) != batch_size:
+                    continue
+                y_data = np.array([x[1] for x in data]).astype('int64').reshape(
+                    batch_size, 1)
+
+                img = to_variable(dy_x_data)
+                label = to_variable(y_data)
+                label._stop_gradient = True
+
+                out = resnet(img)
+                loss = fluid.layers.cross_entropy(input=out, label=label)
+                avg_loss = fluid.layers.mean(x=loss)
+
+                dy_out = avg_loss.numpy()
+                avg_loss.backward()
+
+                optimizer.minimize(avg_loss)
+                resnet.clear_gradients()
+
+                print("epoch id: %d, batch step: %d, loss: %f" % (eop, batch_id, dy_out))
+
+
+if __name__ == '__main__':
+    train_resnet()

dygraph/transformer/README.md

+## 简介
+
+### 任务说明
+
+机器翻译（machine translation, MT）是利用计算机将一种自然语言(源语言)转换为另一种自然语言(目标语言)的过程，输入为源语言句子，输出为相应的目标语言的句子。本示例是机器翻译主流模型 Transformer 的实现和相关介绍。
+
+### 数据集说明
+
+我们使用公开的 [WMT'16 EN-DE 数据集](http://www.statmt.org/wmt16/translation-task.html)训练
+
+
+可以将下载好的wmt16数据集放在`~/.cache/paddle/dataset/wmt16/`目录下
+
+### 安装说明
+
+1. paddle安装
+
+   本项目依赖于 Paddlepaddle Fluid 1.4.1，请参考安装指南进行安装。
+
+2. 安装代码
+3. 环境依赖
+
+### 执行训练：
+利用python解释器执行train.py即可
+
+### 执行效果
+
+    W0422 13:25:53.853921 116144 device_context.cc:261] Please NOTE: device: 0, CUDA Capability: 35, Driver API Version: 9.0, Runtime API Version: 8.0
+    W0422 13:25:53.861614 116144 device_context.cc:269] device: 0, cuDNN Version: 7.0.
+
+    pass num : 0, batch_id: 10, dy_graph avg loss: [9.033163]
+    pass num : 0, batch_id: 20, dy_graph avg loss: [8.869838]
+    pass num : 0, batch_id: 30, dy_graph avg loss: [8.635877]
+    pass num : 0, batch_id: 40, dy_graph avg loss: [8.460026]
+    pass num : 0, batch_id: 50, dy_graph avg loss: [8.293438]
+    pass num : 0, batch_id: 60, dy_graph avg loss: [8.138791]
+    pass num : 0, batch_id: 70, dy_graph avg loss: [7.9594088]
+    pass num : 0, batch_id: 80, dy_graph avg loss: [7.7303553]
+    pass num : 0, batch_id: 90, dy_graph avg loss: [7.6716228]
+    pass num : 0, batch_id: 100, dy_graph avg loss: [7.611051]
+    pass num : 0, batch_id: 110, dy_graph avg loss: [7.4179897]
+    pass num : 0, batch_id: 120, dy_graph avg loss: [7.318419]
+
+## 进阶使用
+
+### 模型原理介绍
+
+Transformer 是论文 [Attention Is All You Need](https://arxiv.org/abs/1706.03762) 中提出的用以完成机器翻译（machine translation, MT）等序列到序列（sequence to sequence, Seq2Seq）学习任务的一种全新网络结构。其同样使用了 Seq2Seq 任务中典型的编码器-解码器（Encoder-Decoder）的框架结构，但相较于此前广泛使用的循环神经网络（Recurrent Neural Network, RNN），其完全使用注意力（Attention）机制来实现序列到序列的建模，整体网络结构如图1所示。
+
+<p align="center">
+<img src="../../PaddleNLP/neural_machine_translation/transformer/images/transformer_network.png" height=400 hspace='10'/> <br />
+图 1. Transformer 网络结构图
+</p>
+
+Encoder 由若干相同的 layer 堆叠组成，每个 layer 主要由多头注意力（Multi-Head Attention）和全连接的前馈（Feed-Forward）网络这两个 sub-layer 构成。
+- Multi-Head Attention 在这里用于实现 Self-Attention，相比于简单的 Attention 机制，其将输入进行多路线性变换后分别计算 Attention 的结果，并将所有结果拼接后再次进行线性变换作为输出。参见图2，其中 Attention 使用的是点积（Dot-Product），并在点积后进行了 scale 的处理以避免因点积结果过大进入 softmax 的饱和区域。
+- Feed-Forward 网络会对序列中的每个位置进行相同的计算（Position-wise），其采用的是两次线性变换中间加以 ReLU 激活的结构。
+
+此外，每个 sub-layer 后还施以 [Residual Connection](http://openaccess.thecvf.com/content_cvpr_2016/papers/He_Deep_Residual_Learning_CVPR_2016_paper.pdf) 和 [Layer Normalization](https://arxiv.org/pdf/1607.06450.pdf) 来促进梯度传播和模型收敛。
+
+<p align="center">
+<img src="../../PaddleNLP/neural_machine_translation/transformer/images/multi_head_attention.png" height=300 hspace='10'/> <br />
+图 2. Multi-Head Attention
+</p>
+
+Decoder 具有和 Encoder 类似的结构，只是相比于组成 Encoder 的 layer ，在组成 Decoder 的 layer 中还多了一个 Multi-Head Attention 的 sub-layer 来实现对 Encoder 输出的 Attention，这个 Encoder-Decoder Attention 在其他 Seq2Seq 模型中也是存在的。

dygraph/transformer/train.py

+from __future__ import print_function
+
+import contextlib
+import paddle.fluid as fluid
+from paddle.fluid.dygraph import Embedding, LayerNorm, FC, to_variable, Layer, guard
+import numpy as np
+import paddle
+import paddle.dataset.wmt16 as wmt16
+np.set_printoptions(suppress=True)
+
+
+@contextlib.contextmanager
+def new_program_scope(main=None, startup=None, scope=None):
+    """
+    base program
+    :param main:
+    :param startup:
+    :param scope:
+    :return:
+    """
+    prog = main if main else fluid.Program()
+    startup_prog = startup if startup else fluid.Program()
+    scope = scope if scope else fluid.core.Scope()
+    with fluid.scope_guard(scope):
+        with fluid.program_guard(prog, startup_prog):
+            with fluid.unique_name.guard():
+                yield
+
+
+# Copy from models
+class TrainTaskConfig(object):
+    """
+    TrainTaskConfig
+    """
+    # support both CPU and GPU now.
+    use_gpu = True
+    # the epoch number to train.
+    pass_num = 30
+    # the number of sequences contained in a mini-batch.
+    # deprecated, set batch_size in args.
+    batch_size = 32
+    # the hyper parameters for Adam optimizer.
+    # This static learning_rate will be multiplied to the LearningRateScheduler
+    # derived learning rate the to get the final learning rate.
+    learning_rate = 2.0
+    beta1 = 0.9
+    beta2 = 0.997
+    eps = 1e-9
+    # the parameters for learning rate scheduling.
+    warmup_steps = 8000
+    # the weight used to mix up the ground-truth distribution and the fixed
+    # uniform distribution in label smoothing when training.
+    # Set this as zero if label smoothing is not wanted.
+    label_smooth_eps = 0.1
+
+
+class ModelHyperParams(object):
+    """
+    ModelHyperParams
+    """
+    # These following five vocabularies related configurations will be set
+    # automatically according to the passed vocabulary path and special tokens.
+    # size of source word dictionary.
+    src_vocab_size = 10000
+    # size of target word dictionay
+    trg_vocab_size = 10000
+    # # index for <bos> token
+    # bos_idx = 0
+    # # index for <eos> token
+    # eos_idx = 1
+    # # index for <unk> token
+    # unk_idx = 2
+
+    src_pad_idx = 0
+
+    # index for <pad> token in target language.
+    trg_pad_idx = 1
+
+    # max length of sequences deciding the size of position encoding table.
+    max_length = 50
+    # the dimension for word embeddings, which is also the last dimension of
+    # the input and output of multi-head attention, position-wise feed-forward
+    # networks, encoder and decoder.
+    d_model = 512
+    # size of the hidden layer in position-wise feed-forward networks.
+    d_inner_hid = 2048
+    # the dimension that keys are projected to for dot-product attention.
+    d_key = 64
+    # the dimension that values are projected to for dot-product attention.
+    d_value = 64
+    # number of head used in multi-head attention.
+    n_head = 8
+    # number of sub-layers to be stacked in the encoder and decoder.
+    n_layer = 6
+    # dropout rates of different modules.
+    prepostprocess_dropout = 0.1
+    attention_dropout = 0.1
+    relu_dropout = 0.1
+    # to process before each sub-layer
+    preprocess_cmd = "n"  # layer normalization
+    # to process after each sub-layer
+    postprocess_cmd = "da"  # dropout + residual connection
+    # random seed used in dropout for CE.
+    dropout_seed = None
+    # the flag indicating whether to share embedding and softmax weights.
+    # vocabularies in source and target should be same for weight sharing.
+    weight_sharing = False
+
+
+# The placeholder for batch_size in compile time. Must be -1 currently to be
+# consistent with some ops' infer-shape output in compile time, such as the
+# sequence_expand op used in beamsearch decoder.
+batch_size = -1
+# The placeholder for squence length in compile time.
+seq_len = ModelHyperParams.max_length
+# Here list the data shapes and data types of all inputs.
+# The shapes here act as placeholder and are set to pass the infer-shape in
+# compile time.
+input_descs = {
+    # The actual data shape of src_word is:
+    # [batch_size, max_src_len_in_batch, 1]
+    "src_word": [(batch_size, seq_len, 1), "int64", 2],
+    # The actual data shape of src_pos is:
+    # [batch_size, max_src_len_in_batch, 1]
+    "src_pos": [(batch_size, seq_len, 1), "int64"],
+    # This input is used to remove attention weights on paddings in the
+    # encoder.
+    # The actual data shape of src_slf_attn_bias is:
+    # [batch_size, n_head, max_src_len_in_batch, max_src_len_in_batch]
+    "src_slf_attn_bias": [(batch_size, ModelHyperParams.n_head, seq_len,
+                           seq_len), "float32"],
+    # The actual data shape of trg_word is:
+    # [batch_size, max_trg_len_in_batch, 1]
+    "trg_word": [(batch_size, seq_len, 1), "int64",
+                 2],  # lod_level is only used in fast decoder.
+    # The actual data shape of trg_pos is:
+    # [batch_size, max_trg_len_in_batch, 1]
+    "trg_pos": [(batch_size, seq_len, 1), "int64"],
+    # This input is used to remove attention weights on paddings and
+    # subsequent words in the decoder.
+    # The actual data shape of trg_slf_attn_bias is:
+    # [batch_size, n_head, max_trg_len_in_batch, max_trg_len_in_batch]
+    "trg_slf_attn_bias": [(batch_size, ModelHyperParams.n_head, seq_len,
+                           seq_len), "float32"],
+    # This input is used to remove attention weights on paddings of the source
+    # input in the encoder-decoder attention.
+    # The actual data shape of trg_src_attn_bias is:
+    # [batch_size, n_head, max_trg_len_in_batch, max_src_len_in_batch]
+    "trg_src_attn_bias": [(batch_size, ModelHyperParams.n_head, seq_len,
+                           seq_len), "float32"],
+    # This input is used in independent decoder program for inference.
+    # The actual data shape of enc_output is:
+    # [batch_size, max_src_len_in_batch, d_model]
+    "enc_output": [(batch_size, seq_len, ModelHyperParams.d_model), "float32"],
+    # The actual data shape of label_word is:
+    # [batch_size * max_trg_len_in_batch, 1]
+    "lbl_word": [(batch_size * seq_len, 1), "int64"],
+    # This input is used to mask out the loss of paddding tokens.
+    # The actual data shape of label_weight is:
+    # [batch_size * max_trg_len_in_batch, 1]
+    "lbl_weight": [(batch_size * seq_len, 1), "float32"],
+    # This input is used in beam-search decoder.
+    "init_score": [(batch_size, 1), "float32", 2],
+    # This input is used in beam-search decoder for the first gather
+    # (cell states updation)
+    "init_idx": [(batch_size, ), "int32"],
+}
+
+# Names of word embedding table which might be reused for weight sharing.
+word_emb_param_names = (
+    "src_word_emb_table",
+    "trg_word_emb_table", )
+# Names of position encoding table which will be initialized externally.
+pos_enc_param_names = (
+    "src_pos_enc_table",
+    "trg_pos_enc_table", )
+# separated inputs for different usages.
+encoder_data_input_fields = (
+    "src_word",
+    "src_pos",
+    "src_slf_attn_bias", )
+decoder_data_input_fields = (
+    "trg_word",
+    "trg_pos",
+    "trg_slf_attn_bias",
+    "trg_src_attn_bias",
+    "enc_output", )
+label_data_input_fields = (
+    "lbl_word",
+    "lbl_weight", )
+# In fast decoder, trg_pos (only containing the current time step) is generated
+# by ops and trg_slf_attn_bias is not needed.
+fast_decoder_data_input_fields = (
+    "trg_word",
+    "init_score",
+    "init_idx",
+    "trg_src_attn_bias", )
+
+
+def merge_cfg_from_list(cfg_list, g_cfgs):
+    """
+    Set the above global configurations using the cfg_list.
+    """
+    assert len(cfg_list) % 2 == 0
+    for key, value in zip(cfg_list[0::2], cfg_list[1::2]):
+        for g_cfg in g_cfgs:
+            if hasattr(g_cfg, key):
+                try:
+                    value = eval(value)
+                except Exception:  # for file path
+                    pass
+                setattr(g_cfg, key, value)
+                break
+
+
+def position_encoding_init(n_position, d_pos_vec):
+    """
+    Generate the initial values for the sinusoid position encoding table.
+    """
+    channels = d_pos_vec
+    position = np.arange(n_position)
+    num_timescales = channels // 2
+    log_timescale_increment = (np.log(float(1e4) / float(1)) /
+                               (num_timescales - 1))
+    inv_timescales = np.exp(np.arange(
+        num_timescales)) * -log_timescale_increment
+    scaled_time = np.expand_dims(position, 1) * np.expand_dims(inv_timescales,
+                                                               0)
+    signal = np.concatenate([np.sin(scaled_time), np.cos(scaled_time)], axis=1)
+    signal = np.pad(signal, [[0, 0], [0, np.mod(channels, 2)]], 'constant')
+    position_enc = signal
+    return position_enc.astype("float32")
+
+
+def create_data(np_values, is_static=False):
+    """
+    create_data
+    :param np_values:
+    :param is_static:
+    :return:
+    """
+    # pdb.set_trace()
+    [
+        src_word_np, src_pos_np, trg_word_np, trg_pos_np, src_slf_attn_bias_np,
+        trg_slf_attn_bias_np, trg_src_attn_bias_np, lbl_word_np, lbl_weight_np
+    ] = np_values
+
+    if is_static:
+        return [
+            src_word_np, src_pos_np, src_slf_attn_bias_np, trg_word_np,
+            trg_pos_np, trg_slf_attn_bias_np, trg_src_attn_bias_np, lbl_word_np,
+            lbl_weight_np
+        ]
+    else:
+        enc_inputs = [
+            to_variable(
+                src_word_np, name='src_word'), to_variable(
+                    src_pos_np, name='src_pos'), to_variable(
+                        src_slf_attn_bias_np, name='src_slf_attn_bias')
+        ]
+        dec_inputs = [
+            to_variable(
+                trg_word_np, name='trg_word'), to_variable(
+                    trg_pos_np, name='trg_pos'), to_variable(
+                        trg_slf_attn_bias_np, name='trg_slf_attn_bias'),
+            to_variable(
+                trg_src_attn_bias_np, name='trg_src_attn_bias')
+        ]
+        label = to_variable(lbl_word_np, name='lbl_word')
+        weight = to_variable(lbl_weight_np, name='lbl_weight')
+        return enc_inputs, dec_inputs, label, weight
+
+
+def create_feed_dict_list(data, init=False):
+    """
+    create_feed_dict_list
+    :param data:
+    :param init:
+    :return:
+    """
+    if init:
+        data_input_names = encoder_data_input_fields + \
+                           decoder_data_input_fields[:-1] + label_data_input_fields + pos_enc_param_names
+    else:
+        data_input_names = encoder_data_input_fields + \
+                           decoder_data_input_fields[:-1] + label_data_input_fields
+    feed_dict_list = dict()
+    for i in range(len(data_input_names)):
+        feed_dict_list[data_input_names[i]] = data[i]
+    return feed_dict_list
+
+
+def make_all_inputs(input_fields):
+    """
+    Define the input data layers for the transformer model.
+    """
+    inputs = []
+    for input_field in input_fields:
+        input_var = fluid.layers.data(
+            name=input_field,
+            shape=input_descs[input_field][0],
+            dtype=input_descs[input_field][1],
+            lod_level=input_descs[input_field][2]
+            if len(input_descs[input_field]) == 3 else 0,
+            append_batch_size=False)
+        inputs.append(input_var)
+    return inputs
+
+
+def prepare_batch_input(insts, src_pad_idx, trg_pad_idx, n_head):
+    """
+    Pad the instances to the max sequence length in batch, and generate the
+    corresponding position data and attention bias. Then, convert the numpy
+    data to tensors and return a dict mapping names to tensors.
+    """
+
+    def __pad_batch_data(insts,
+                         pad_idx,
+                         n_head,
+                         is_target=False,
+                         is_label=False,
+                         return_attn_bias=True,
+                         return_max_len=True,
+                         return_num_token=False):
+        """
+        Pad the instances to the max sequence length in batch, and generate the
+        corresponding position data and attention bias.
+        """
+        return_list = []
+        max_len = max(len(inst) for inst in insts)
+        # Any token included in dict can be used to pad, since the paddings' loss
+        # will be masked out by weights and make no effect on parameter gradients.
+        inst_data = np.array(
+            [inst + [pad_idx] * (max_len - len(inst)) for inst in insts])
+        return_list += [inst_data.astype("int64").reshape([-1, 1])]
+        if is_label:  # label weight
+            inst_weight = np.array([[1.] * len(inst) + [0.] *
+                                    (max_len - len(inst)) for inst in insts])
+            return_list += [inst_weight.astype("float32").reshape([-1, 1])]
+        else:  # position data
+            inst_pos = np.array([
+                list(range(0, len(inst))) + [0] * (max_len - len(inst))
+                for inst in insts
+            ])
+            return_list += [inst_pos.astype("int64").reshape([-1, 1])]
+        if return_attn_bias:
+            if is_target:
+                # This is used to avoid attention on paddings and subsequent
+                # words.
+                slf_attn_bias_data = np.ones(
+                    (inst_data.shape[0], max_len, max_len))
+                slf_attn_bias_data = np.triu(
+                    slf_attn_bias_data, 1).reshape([-1, 1, max_len, max_len])
+                slf_attn_bias_data = np.tile(slf_attn_bias_data,
+                                             [1, n_head, 1, 1]) * [-1e9]
+            else:
+                # This is used to avoid attention on paddings.
+                slf_attn_bias_data = np.array([[0] * len(inst) + [-1e9] *
+                                               (max_len - len(inst))
+                                               for inst in insts])
+                slf_attn_bias_data = np.tile(
+                    slf_attn_bias_data.reshape([-1, 1, 1, max_len]),
+                    [1, n_head, max_len, 1])
+            return_list += [slf_attn_bias_data.astype("float32")]
+        if return_max_len:
+            return_list += [max_len]
+        if return_num_token:
+            num_token = 0
+            for inst in insts:
+                num_token += len(inst)
+            return_list += [num_token]
+        return return_list if len(return_list) > 1 else return_list[0]
+
+    src_word, src_pos, src_slf_attn_bias, src_max_len = __pad_batch_data(
+        [inst[0] for inst in insts], src_pad_idx, n_head, is_target=False)
+    src_word = src_word.reshape(-1, src_max_len, 1)
+    src_pos = src_pos.reshape(-1, src_max_len, 1)
+    trg_word, trg_pos, trg_slf_attn_bias, trg_max_len = __pad_batch_data(
+        [inst[1] for inst in insts], trg_pad_idx, n_head, is_target=True)
+    trg_word = trg_word.reshape(-1, trg_max_len, 1)
+    trg_pos = trg_pos.reshape(-1, trg_max_len, 1)
+
+    trg_src_attn_bias = np.tile(src_slf_attn_bias[:, :, ::src_max_len, :],
+                                [1, 1, trg_max_len, 1]).astype("float32")
+
+    lbl_word, lbl_weight, num_token = __pad_batch_data(
+        [inst[2] for inst in insts],
+        trg_pad_idx,
+        n_head,
+        is_target=False,
+        is_label=True,
+        return_attn_bias=False,
+        return_max_len=False,
+        return_num_token=True)
+
+    return [
+        src_word, src_pos, trg_word, trg_pos, src_slf_attn_bias,
+        trg_slf_attn_bias, trg_src_attn_bias, lbl_word, lbl_weight
+    ]
+
+
+pos_inp1 = position_encoding_init(ModelHyperParams.max_length + 1,
+                                  ModelHyperParams.d_model)
+pos_inp2 = position_encoding_init(ModelHyperParams.max_length + 1,
+                                  ModelHyperParams.d_model)
+
+
+class PrePostProcessLayer(Layer):
+    """
+    PrePostProcessLayer
+    """
+
+    def __init__(self, name_scope, process_cmd, shape_len=None):
+        super(PrePostProcessLayer, self).__init__(name_scope)
+        for cmd in process_cmd:
+            if cmd == "n":
+                self._layer_norm = LayerNorm(
+                    name_scope=self.full_name(),
+                    begin_norm_axis=shape_len - 1,
+                    param_attr=fluid.ParamAttr(
+                        initializer=fluid.initializer.Constant(1.)),
+                    bias_attr=fluid.ParamAttr(
+                        initializer=fluid.initializer.Constant(0.)))
+
+    def forward(self, prev_out, out, process_cmd, dropout_rate=0.):
+        """
+        forward
+        :param prev_out:
+        :param out:
+        :param process_cmd:
+        :param dropout_rate:
+        :return:
+        """
+        for cmd in process_cmd:
+            if cmd == "a":  # add residual connection
+                out = out + prev_out if prev_out else out
+            elif cmd == "n":  # add layer normalization
+                out = self._layer_norm(out)
+            elif cmd == "d":  # add dropout
+                if dropout_rate:
+                    out = fluid.layers.dropout(
+                        out,
+                        dropout_prob=dropout_rate,
+                        seed=ModelHyperParams.dropout_seed,
+                        is_test=False)
+        return out
+
+
+class PositionwiseFeedForwardLayer(Layer):
+    """
+    PositionwiseFeedForwardLayer
+    """
+
+    def __init__(self, name_scope, d_inner_hid, d_hid, dropout_rate):
+        super(PositionwiseFeedForwardLayer, self).__init__(name_scope)
+        self._i2h = FC(name_scope=self.full_name(),
+                       size=d_inner_hid,
+                       num_flatten_dims=2,
+                       act="relu")
+        self._h2o = FC(name_scope=self.full_name(),
+                       size=d_hid,
+                       num_flatten_dims=2)
+        self._dropout_rate = dropout_rate
+
+    def forward(self, x):
+        """
+        forward
+        :param x:
+        :return:
+        """
+        hidden = self._i2h(x)
+        if self._dropout_rate:
+            hidden = fluid.layers.dropout(
+                hidden,
+                dropout_prob=self._dropout_rate,
+                seed=ModelHyperParams.dropout_seed,
+                is_test=False)
+        out = self._h2o(hidden)
+        return out
+
+
+class MultiHeadAttentionLayer(Layer):
+    """
+    MultiHeadAttentionLayer
+    """
+
+    def __init__(self,
+                 name_scope,
+                 d_key,
+                 d_value,
+                 d_model,
+                 n_head=1,
+                 dropout_rate=0.,
+                 cache=None,
+                 gather_idx=None,
+                 static_kv=False):
+        super(MultiHeadAttentionLayer, self).__init__(name_scope)
+        self._n_head = n_head
+        self._d_key = d_key
+        self._d_value = d_value
+        self._d_model = d_model
+        self._dropout_rate = dropout_rate
+        self._q_fc = FC(name_scope=self.full_name(),
+                        size=d_key * n_head,
+                        bias_attr=False,
+                        num_flatten_dims=2)
+        self._k_fc = FC(name_scope=self.full_name(),
+                        size=d_key * n_head,
+                        bias_attr=False,
+                        num_flatten_dims=2)
+        self._v_fc = FC(name_scope=self.full_name(),
+                        size=d_value * n_head,
+                        bias_attr=False,
+                        num_flatten_dims=2)
+        self._proj_fc = FC(name_scope=self.full_name(),
+                           size=self._d_model,
+                           bias_attr=False,
+                           num_flatten_dims=2)
+
+    def forward(self, queries, keys, values, attn_bias):
+        """
+        forward
+        :param queries:
+        :param keys:
+        :param values:
+        :param attn_bias:
+        :return:
+        """
+        # compute q ,k ,v
+        keys = queries if keys is None else keys
+        values = keys if values is None else values
+
+        q = self._q_fc(queries)
+        k = self._k_fc(keys)
+        v = self._v_fc(values)
+
+        # split head
+        reshaped_q = fluid.layers.reshape(
+            x=q, shape=[0, 0, self._n_head, self._d_key], inplace=False)
+        transpose_q = fluid.layers.transpose(x=reshaped_q, perm=[0, 2, 1, 3])
+        reshaped_k = fluid.layers.reshape(
+            x=k, shape=[0, 0, self._n_head, self._d_key], inplace=False)
+        transpose_k = fluid.layers.transpose(x=reshaped_k, perm=[0, 2, 1, 3])
+        reshaped_v = fluid.layers.reshape(
+            x=v, shape=[0, 0, self._n_head, self._d_value], inplace=False)
+        transpose_v = fluid.layers.transpose(x=reshaped_v, perm=[0, 2, 1, 3])
+
+        # scale dot product attention
+        product = fluid.layers.matmul(
+            x=transpose_q,
+            y=transpose_k,
+            transpose_y=True,
+            alpha=self._d_model**-0.5)
+        if attn_bias:
+            product += attn_bias
+        weights = fluid.layers.softmax(product)
+        if self._dropout_rate:
+            weights_droped = fluid.layers.dropout(
+                weights,
+                dropout_prob=self._dropout_rate,
+                seed=ModelHyperParams.dropout_seed,
+                is_test=False)
+            out = fluid.layers.matmul(weights_droped, transpose_v)
+        else:
+            out = fluid.layers.matmul(weights, transpose_v)
+
+        # combine heads
+        if len(out.shape) != 4:
+            raise ValueError("Input(x) should be a 4-D Tensor.")
+        trans_x = fluid.layers.transpose(out, perm=[0, 2, 1, 3])
+        final_out = fluid.layers.reshape(
+            x=trans_x,
+            shape=[0, 0, trans_x.shape[2] * trans_x.shape[3]],
+            inplace=False)
+
+        # fc to output
+        proj_out = self._proj_fc(final_out)
+        return proj_out
+
+
+class EncoderSubLayer(Layer):
+    """
+    EncoderSubLayer
+    """
+
+    def __init__(self,
+                 name_scope,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd="n",
+                 postprocess_cmd="da"):
+
+        super(EncoderSubLayer, self).__init__(name_scope)
+        self._preprocess_cmd = preprocess_cmd
+        self._postprocess_cmd = postprocess_cmd
+        self._prepostprocess_dropout = prepostprocess_dropout
+
+        self._preprocess_layer = PrePostProcessLayer(self.full_name(),
+                                                     self._preprocess_cmd, 3)
+        self._multihead_attention_layer = MultiHeadAttentionLayer(
+            self.full_name(), d_key, d_value, d_model, n_head,
+            attention_dropout)
+        self._postprocess_layer = PrePostProcessLayer(
+            self.full_name(), self._postprocess_cmd, None)
+        self._preprocess_layer2 = PrePostProcessLayer(self.full_name(),
+                                                      self._preprocess_cmd, 3)
+        self._positionwise_feed_forward = PositionwiseFeedForwardLayer(
+            self.full_name(), d_inner_hid, d_model, relu_dropout)
+        self._postprocess_layer2 = PrePostProcessLayer(
+            self.full_name(), self._postprocess_cmd, None)
+
+    def forward(self, enc_input, attn_bias):
+        """
+        forward
+        :param enc_input:
+        :param attn_bias:
+        :return:
+        """
+        pre_process_multihead = self._preprocess_layer(
+            None, enc_input, self._preprocess_cmd, self._prepostprocess_dropout)
+        attn_output = self._multihead_attention_layer(pre_process_multihead,
+                                                      None, None, attn_bias)
+        attn_output = self._postprocess_layer(enc_input, attn_output,
+                                              self._postprocess_cmd,
+                                              self._prepostprocess_dropout)
+        pre_process2_output = self._preprocess_layer2(
+            None, attn_output, self._preprocess_cmd,
+            self._prepostprocess_dropout)
+        ffd_output = self._positionwise_feed_forward(pre_process2_output)
+        return self._postprocess_layer2(attn_output, ffd_output,
+                                        self._postprocess_cmd,
+                                        self._prepostprocess_dropout)
+
+
+class EncoderLayer(Layer):
+    """
+    encoder
+    """
+
+    def __init__(self,
+                 name_scope,
+                 n_layer,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd="n",
+                 postprocess_cmd="da"):
+
+        super(EncoderLayer, self).__init__(name_scope)
+        self._preprocess_cmd = preprocess_cmd
+        self._encoder_sublayers = list()
+        self._prepostprocess_dropout = prepostprocess_dropout
+        self._n_layer = n_layer
+        self._preprocess_layer = PrePostProcessLayer(self.full_name(),
+                                                     self._preprocess_cmd, 3)
+        for i in range(n_layer):
+            self._encoder_sublayers.append(
+                self.add_sublayer(
+                    'esl_%d' % i,
+                    EncoderSubLayer(
+                        self.full_name(), n_head, d_key, d_value, d_model,
+                        d_inner_hid, prepostprocess_dropout, attention_dropout,
+                        relu_dropout, preprocess_cmd, postprocess_cmd)))
+
+    def forward(self, enc_input, attn_bias):
+        """
+        forward
+        :param enc_input:
+        :param attn_bias:
+        :return:
+        """
+        for i in range(self._n_layer):
+            enc_output = self._encoder_sublayers[i](enc_input, attn_bias)
+            enc_input = enc_output
+
+        return self._preprocess_layer(None, enc_output, self._preprocess_cmd,
+                                      self._prepostprocess_dropout)
+
+
+class PrepareEncoderDecoderLayer(Layer):
+    """
+    PrepareEncoderDecoderLayer
+    """
+
+    def __init__(self,
+                 name_scope,
+                 src_vocab_size,
+                 src_emb_dim,
+                 src_max_len,
+                 dropout_rate,
+                 word_emb_param_name=None,
+                 pos_enc_param_name=None):
+        super(PrepareEncoderDecoderLayer, self).__init__(name_scope)
+        self._src_max_len = src_max_len
+        self._src_emb_dim = src_emb_dim
+        self._src_vocab_size = src_vocab_size
+        self._dropout_rate = dropout_rate
+        self._input_emb = Embedding(
+            name_scope=self.full_name(),
+            size=[src_vocab_size, src_emb_dim],
+            padding_idx=0,
+            param_attr=fluid.ParamAttr(
+                name=word_emb_param_name,
+                initializer=fluid.initializer.Normal(0., src_emb_dim**-0.5)))
+
+        if pos_enc_param_name is pos_enc_param_names[0]:
+            pos_inp = pos_inp1
+        else:
+            pos_inp = pos_inp2
+        self._pos_emb = Embedding(
+            name_scope=self.full_name(),
+            size=[self._src_max_len, src_emb_dim],
+            param_attr=fluid.ParamAttr(
+                name=pos_enc_param_name,
+                initializer=fluid.initializer.NumpyArrayInitializer(pos_inp),
+                trainable=False))
+
+        # use in dygraph_mode to fit different length batch
+        # self._pos_emb._w = to_variable(
+        #     position_encoding_init(self._src_max_len, self._src_emb_dim))
+
+    def forward(self, src_word, src_pos):
+        """
+        forward
+        :param src_word:
+        :param src_pos:
+        :return:
+        """
+        # print("here")
+        # print(self._input_emb._w._numpy().shape)
+        src_word_emb = self._input_emb(src_word)
+
+        src_word_emb = fluid.layers.scale(
+            x=src_word_emb, scale=self._src_emb_dim**0.5)
+        # # TODO change this to fit dynamic length input
+        src_pos_emb = self._pos_emb(src_pos)
+        src_pos_emb.stop_gradient = True
+        enc_input = src_word_emb + src_pos_emb
+        return fluid.layers.dropout(
+            enc_input,
+            dropout_prob=self._dropout_rate,
+            seed=ModelHyperParams.dropout_seed,
+            is_test=False) if self._dropout_rate else enc_input
+
+
+class WrapEncoderLayer(Layer):
+    """
+    encoderlayer
+    """
+
+    def __init__(self, name_cope, src_vocab_size, max_length, n_layer, n_head,
+                 d_key, d_value, d_model, d_inner_hid, prepostprocess_dropout,
+                 attention_dropout, relu_dropout, preprocess_cmd,
+                 postprocess_cmd, weight_sharing):
+        """
+        The wrapper assembles together all needed layers for the encoder.
+        """
+        super(WrapEncoderLayer, self).__init__(name_cope)
+
+        self._prepare_encoder_layer = PrepareEncoderDecoderLayer(
+            self.full_name(),
+            src_vocab_size,
+            d_model,
+            max_length,
+            prepostprocess_dropout,
+            word_emb_param_name=word_emb_param_names[0],
+            pos_enc_param_name=pos_enc_param_names[0])
+        self._encoder = EncoderLayer(
+            self.full_name(), n_layer, n_head, d_key, d_value, d_model,
+            d_inner_hid, prepostprocess_dropout, attention_dropout,
+            relu_dropout, preprocess_cmd, postprocess_cmd)
+
+    def forward(self, enc_inputs):
+        """forward"""
+        src_word, src_pos, src_slf_attn_bias = enc_inputs
+        enc_input = self._prepare_encoder_layer(src_word, src_pos)
+        enc_output = self._encoder(enc_input, src_slf_attn_bias)
+        return enc_output
+
+
+class DecoderSubLayer(Layer):
+    """
+    decoder
+    """
+
+    def __init__(self,
+                 name_scope,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd,
+                 postprocess_cmd,
+                 cache=None,
+                 gather_idx=None):
+        super(DecoderSubLayer, self).__init__(name_scope)
+        self._postprocess_cmd = postprocess_cmd
+        self._preprocess_cmd = preprocess_cmd
+        self._prepostprcess_dropout = prepostprocess_dropout
+        self._pre_process_layer = PrePostProcessLayer(self.full_name(),
+                                                      preprocess_cmd, 3)
+        self._multihead_attention_layer = MultiHeadAttentionLayer(
+            self.full_name(),
+            d_key,
+            d_value,
+            d_model,
+            n_head,
+            attention_dropout,
+            cache=cache,
+            gather_idx=gather_idx)
+        self._post_process_layer = PrePostProcessLayer(self.full_name(),
+                                                       postprocess_cmd, None)
+        self._pre_process_layer2 = PrePostProcessLayer(self.full_name(),
+                                                       preprocess_cmd, 3)
+        self._multihead_attention_layer2 = MultiHeadAttentionLayer(
+            self.full_name(),
+            d_key,
+            d_value,
+            d_model,
+            n_head,
+            attention_dropout,
+            cache=cache,
+            gather_idx=gather_idx,
+            static_kv=True)
+        self._post_process_layer2 = PrePostProcessLayer(self.full_name(),
+                                                        postprocess_cmd, None)
+        self._pre_process_layer3 = PrePostProcessLayer(self.full_name(),
+                                                       preprocess_cmd, 3)
+        self._positionwise_feed_forward_layer = PositionwiseFeedForwardLayer(
+            self.full_name(), d_inner_hid, d_model, relu_dropout)
+        self._post_process_layer3 = PrePostProcessLayer(self.full_name(),
+                                                        postprocess_cmd, None)
+
+    def forward(self, dec_input, enc_output, slf_attn_bias, dec_enc_attn_bias):
+        """
+        forward
+        :param dec_input:
+        :param enc_output:
+        :param slf_attn_bias:
+        :param dec_enc_attn_bias:
+        :return:
+        """
+        pre_process_rlt = self._pre_process_layer(
+            None, dec_input, self._preprocess_cmd, self._prepostprcess_dropout)
+        slf_attn_output = self._multihead_attention_layer(pre_process_rlt, None,
+                                                          None, slf_attn_bias)
+        slf_attn_output_pp = self._post_process_layer(
+            dec_input, slf_attn_output, self._postprocess_cmd,
+            self._prepostprcess_dropout)
+        pre_process_rlt2 = self._pre_process_layer2(None, slf_attn_output_pp,
+                                                    self._preprocess_cmd,
+                                                    self._prepostprcess_dropout)
+        enc_attn_output_pp = self._multihead_attention_layer2(
+            pre_process_rlt2, enc_output, enc_output, dec_enc_attn_bias)
+        enc_attn_output = self._post_process_layer2(
+            slf_attn_output_pp, enc_attn_output_pp, self._postprocess_cmd,
+            self._prepostprcess_dropout)
+        pre_process_rlt3 = self._pre_process_layer3(None, enc_attn_output,
+                                                    self._preprocess_cmd,
+                                                    self._prepostprcess_dropout)
+        ffd_output = self._positionwise_feed_forward_layer(pre_process_rlt3)
+        dec_output = self._post_process_layer3(enc_attn_output, ffd_output,
+                                               self._postprocess_cmd,
+                                               self._prepostprcess_dropout)
+        return dec_output
+
+
+class DecoderLayer(Layer):
+    """
+    decoder
+    """
+
+    def __init__(self,
+                 name_scope,
+                 n_layer,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd,
+                 postprocess_cmd,
+                 caches=None,
+                 gather_idx=None):
+        super(DecoderLayer, self).__init__(name_scope)
+        self._pre_process_layer = PrePostProcessLayer(self.full_name(),
+                                                      preprocess_cmd, 3)
+        self._decoder_sub_layers = list()
+        self._n_layer = n_layer
+        self._preprocess_cmd = preprocess_cmd
+        self._prepostprocess_dropout = prepostprocess_dropout
+        for i in range(n_layer):
+            self._decoder_sub_layers.append(
+                self.add_sublayer(
+                    'dsl_%d' % i,
+                    DecoderSubLayer(
+                        self.full_name(),
+                        n_head,
+                        d_key,
+                        d_value,
+                        d_model,
+                        d_inner_hid,
+                        prepostprocess_dropout,
+                        attention_dropout,
+                        relu_dropout,
+                        preprocess_cmd,
+                        postprocess_cmd,
+                        cache=None if caches is None else caches[i],
+                        gather_idx=gather_idx)))
+
+    def forward(self, dec_input, enc_output, dec_slf_attn_bias,
+                dec_enc_attn_bias):
+        """
+        forward
+        :param dec_input:
+        :param enc_output:
+        :param dec_slf_attn_bias:
+        :param dec_enc_attn_bias:
+        :return:
+        """
+        for i in range(self._n_layer):
+            tmp_dec_output = self._decoder_sub_layers[i](
+                dec_input, enc_output, dec_slf_attn_bias, dec_enc_attn_bias)
+            dec_input = tmp_dec_output
+
+        dec_output = self._pre_process_layer(None, tmp_dec_output,
+                                             self._preprocess_cmd,
+                                             self._prepostprocess_dropout)
+        return dec_output
+
+
+class WrapDecoderLayer(Layer):
+    """
+    decoder
+    """
+
+    def __init__(self,
+                 name_scope,
+                 trg_vocab_size,
+                 max_length,
+                 n_layer,
+                 n_head,
+                 d_key,
+                 d_value,
+                 d_model,
+                 d_inner_hid,
+                 prepostprocess_dropout,
+                 attention_dropout,
+                 relu_dropout,
+                 preprocess_cmd,
+                 postprocess_cmd,
+                 weight_sharing,
+                 caches=None,
+                 gather_idx=None):
+        """
+        The wrapper assembles together all needed layers for the encoder.
+        """
+        super(WrapDecoderLayer, self).__init__(name_scope)
+
+        self._prepare_decoder_layer = PrepareEncoderDecoderLayer(
+            self.full_name(),
+            trg_vocab_size,
+            d_model,
+            max_length,
+            prepostprocess_dropout,
+            word_emb_param_name=word_emb_param_names[1],
+            pos_enc_param_name=pos_enc_param_names[1])
+        self._decoder_layer = DecoderLayer(
+            self.full_name(),
+            n_layer,
+            n_head,
+            d_key,
+            d_value,
+            d_model,
+            d_inner_hid,
+            prepostprocess_dropout,
+            attention_dropout,
+            relu_dropout,
+            preprocess_cmd,
+            postprocess_cmd,
+            caches=caches,
+            gather_idx=gather_idx)
+        self._weight_sharing = weight_sharing
+        if not weight_sharing:
+            self._fc = FC(self.full_name(),
+                          size=trg_vocab_size,
+                          bias_attr=False)
+
+    def forward(self, dec_inputs=None, enc_output=None):
+        """
+        forward
+        :param dec_inputs:
+        :param enc_output:
+        :return:
+        """
+        trg_word, trg_pos, trg_slf_attn_bias, trg_src_attn_bias = dec_inputs
+        dec_input = self._prepare_decoder_layer(trg_word, trg_pos)
+        dec_output = self._decoder_layer(dec_input, enc_output,
+                                         trg_slf_attn_bias, trg_src_attn_bias)
+
+        dec_output_reshape = fluid.layers.reshape(
+            dec_output, shape=[-1, dec_output.shape[-1]], inplace=False)
+
+        if self._weight_sharing:
+            predict = fluid.layers.matmul(
+                x=dec_output_reshape,
+                y=self._prepare_decoder_layer._input_emb._w,
+                transpose_y=True)
+        else:
+            predict = self._fc(dec_output_reshape)
+
+        if dec_inputs is None:
+            # Return probs for independent decoder program.
+            predict_out = fluid.layers.softmax(predict)
+            return predict_out
+        return predict
+
+
+class TransFormer(Layer):
+    """
+    model
+    """
+
+    def __init__(self, name_scope, src_vocab_size, trg_vocab_size, max_length,
+                 n_layer, n_head, d_key, d_value, d_model, d_inner_hid,
+                 prepostprocess_dropout, attention_dropout, relu_dropout,
+                 preprocess_cmd, postprocess_cmd, weight_sharing,
+                 label_smooth_eps):
+        super(TransFormer, self).__init__(name_scope)
+        self._label_smooth_eps = label_smooth_eps
+        self._trg_vocab_size = trg_vocab_size
+        if weight_sharing:
+            assert src_vocab_size == trg_vocab_size, (
+                "Vocabularies in source and target should be same for weight sharing."
+            )
+        self._wrap_encoder_layer = WrapEncoderLayer(
+            self.full_name(), src_vocab_size, max_length, n_layer, n_head,
+            d_key, d_value, d_model, d_inner_hid, prepostprocess_dropout,
+            attention_dropout, relu_dropout, preprocess_cmd, postprocess_cmd,
+            weight_sharing)
+        self._wrap_decoder_layer = WrapDecoderLayer(
+            self.full_name(), trg_vocab_size, max_length, n_layer, n_head,
+            d_key, d_value, d_model, d_inner_hid, prepostprocess_dropout,
+            attention_dropout, relu_dropout, preprocess_cmd, postprocess_cmd,
+            weight_sharing)
+
+        if weight_sharing:
+            self._wrap_decoder_layer._prepare_decoder_layer._input_emb._w = self._wrap_encoder_layer._prepare_encoder_layer._input_emb._w
+
+    def forward(self, enc_inputs, dec_inputs, label, weights):
+        """
+        forward
+        :param enc_inputs:
+        :param dec_inputs:
+        :param label:
+        :param weights:
+        :return:
+        """
+        enc_output = self._wrap_encoder_layer(enc_inputs)
+        predict = self._wrap_decoder_layer(dec_inputs, enc_output)
+        if self._label_smooth_eps:
+            label_out = fluid.layers.label_smooth(
+                label=fluid.layers.one_hot(
+                    input=label, depth=self._trg_vocab_size),
+                epsilon=self._label_smooth_eps)
+
+        cost = fluid.layers.softmax_with_cross_entropy(
+            logits=predict,
+            label=label_out,
+            soft_label=True if self._label_smooth_eps else False)
+        weighted_cost = cost * weights
+        sum_cost = fluid.layers.reduce_sum(weighted_cost)
+        token_num = fluid.layers.reduce_sum(weights)
+        token_num.stop_gradient = True
+        avg_cost = sum_cost / token_num
+        return sum_cost, avg_cost, predict, token_num
+
+
+def train():
+    """
+    train models
+    :return:
+    """
+
+    with guard():
+        transformer = TransFormer(
+            'transformer', ModelHyperParams.src_vocab_size,
+            ModelHyperParams.trg_vocab_size, ModelHyperParams.max_length + 1,
+            ModelHyperParams.n_layer, ModelHyperParams.n_head,
+            ModelHyperParams.d_key, ModelHyperParams.d_value,
+            ModelHyperParams.d_model, ModelHyperParams.d_inner_hid,
+            ModelHyperParams.prepostprocess_dropout,
+            ModelHyperParams.attention_dropout, ModelHyperParams.relu_dropout,
+            ModelHyperParams.preprocess_cmd, ModelHyperParams.postprocess_cmd,
+            ModelHyperParams.weight_sharing, TrainTaskConfig.label_smooth_eps)
+
+        optimizer = fluid.optimizer.SGD(learning_rate=0.003)
+
+        reader = paddle.batch(
+            wmt16.train(ModelHyperParams.src_vocab_size,
+                        ModelHyperParams.trg_vocab_size),
+            batch_size=TrainTaskConfig.batch_size)
+        for i in range(200):
+            dy_step = 0
+            for batch in reader():
+                np_values = prepare_batch_input(
+                    batch, ModelHyperParams.src_pad_idx,
+                    ModelHyperParams.trg_pad_idx, ModelHyperParams.n_head)
+
+                enc_inputs, dec_inputs, label, weights = create_data(np_values)
+                dy_sum_cost, dy_avg_cost, dy_predict, dy_token_num = transformer(
+                    enc_inputs, dec_inputs, label, weights)
+                dy_avg_cost.backward()
+                optimizer.minimize(dy_avg_cost)
+                transformer.clear_gradients()
+                dy_step = dy_step + 1
+                if dy_step % 10 == 0:
+                    print("pass num : {}, batch_id: {}, dy_graph avg loss: {}".
+                          format(i, dy_step, dy_avg_cost.numpy()))
+            print("pass : {} finished".format(i))
+
+
+if __name__ == '__main__':
+    train()