提交 6cf6e252 编写于 作者: W weixing02

Add inference documentation

上级 35e55636
......@@ -3,5 +3,6 @@
.. toctree::
:maxdepth: 1
optimization/index_cn.rst
inference/inference_support_in_fluid.md
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:maxdepth: 1
optimization/index_en.rst
inference/inference_support_in_fluid.md
# Fluid Inference使用指南
- Python Inference API
- 编译Fluid Inference库
- Inference C++ API
- Inference实例
- Inference计算优化
## Python Inference API **[改进中]**
- [保存Inference模型](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/io.py#L295)
```python
def save_inference_model(dirname,
feeded_var_names,
target_vars,
executor,
main_program=None,
model_filename=None,
params_filename=None):
```
Inference模型和参数将会保存到`dirname`目录下:
- 序列化的模型
- `model_filename``None`,保存到`dirname/__model__`
- `model_filename``None`,保存到`dirname/model_filename`
- 参数
- `params_filename``None`,单独保存到各个独立的文件,各文件以参数变量的名字命名
- `params_filename``None`,保存到`dirname/params_filename`
- 两种存储格式
- 参数保存到各个独立的文件
- 如,设置`model_filename``None``params_filename``None`
```bash
$ cd recognize_digits_conv.inference.model
$ ls
$ __model__ batch_norm_1.w_0 batch_norm_1.w_2 conv2d_2.w_0 conv2d_3.w_0 fc_1.w_0 batch_norm_1.b_0 batch_norm_1.w_1 conv2d_2.b_0 conv2d_3.b_0 fc_1.b_0
```
- 参数保存到同一个文件
- 如,设置`model_filename``None``params_filename``__params__`
```bash
$ cd recognize_digits_conv.inference.model
$ ls
$ __model__ __params__
```
- [加载Inference模型](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/io.py#L380)
```python
def load_inference_model(dirname,
executor,
model_filename=None,
params_filename=None):
...
return [program, feed_target_names, fetch_targets]
```
## 编译Fluid Inference库
- **不需要额外的CMake选项**
- 1、 配置CMake命令,更多配置请参考[源码编译PaddlePaddle](http://www.paddlepaddle.org/docs/develop/documentation/zh/build_and_install/build_from_source_cn.html)
```bash
$ git clone https://github.com/PaddlePaddle/Paddle.git
$ cd Paddle
$ mkdir build
$ cd build
$ cmake -DCMAKE_INSTALL_PREFIX=your/path/to/paddle_inference_lib \
-DCMAKE_BUILD_TYPE=Release \
-DWITH_PYTHON=ON \
-DWITH_MKL=OFF \
-DWITH_GPU=OFF \
..
```
- 2、 编译PaddlePaddle
```bash
$ make
```
- 3、 部署。执行如下命令将PaddlePaddle Fluid Inference库部署到`your/path/to/paddle_inference_lib`目录。
```bash
$ make inference_lib_dist
```
- 目录结构
```bash
$ cd your/path/to/paddle_inference_lib
$ tree
.
|-- paddle
| `-- fluid
| |-- framework
| |-- inference
| | |-- io.h
| | `-- libpaddle_fluid.so
| |-- memory
| |-- platform
| `-- string
|-- third_party
| |-- eigen3
| `-- install
| |-- gflags
| |-- glog
| `-- protobuf
`-- ...
```
假设`PADDLE_ROOT=your/path/to/paddle_inference_lib`
## 链接Fluid Inference库
- [示例项目](https://github.com/luotao1/fluid_inference_example.git)
- GCC配置
```bash
$ g++ -o a.out -std=c++11 main.cc \
-I${PADDLE_ROOT}/ \
-I${PADDLE_ROOT}/third_party/install/gflags/include \
-I${PADDLE_ROOT}/third_party/install/glog/include \
-I${PADDLE_ROOT}/third_party/install/protobuf/include \
-I${PADDLE_ROOT}/third_party/eigen3 \
-L${PADDLE_ROOT}/paddle/fluid/inference -lpaddle_fluid \
-lrt -ldl -lpthread
```
- CMake配置
```cmake
include_directories(${PADDLE_ROOT}/)
include_directories(${PADDLE_ROOT}/third_party/install/gflags/include)
include_directories(${PADDLE_ROOT}/third_party/install/glog/include)
include_directories(${PADDLE_ROOT}/third_party/install/protobuf/include)
include_directories(${PADDLE_ROOT}/third_party/eigen3)
target_link_libraries(${TARGET_NAME}
${PADDLE_ROOT}/paddle/fluid/inference/libpaddle_fluid.so
-lrt -ldl -lpthread)
```
- 设置环境变量:
`export LD_LIBRARY_PATH=${PADDLE_ROOT}/paddle/fluid/inference:$LD_LIBRARY_PATH`
## C++ Inference API
- [推断流程](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/test_helper.h#L91)
- 1、 初始化设备
```cpp
#include "paddle/fluid/framework/init.h"
paddle::framework::InitDevices(false);
```
- 2、 定义place,executor,scope
```cpp
auto place = paddle::platform::CPUPlace();
auto executor = paddle::framework::Executor(place);
auto* scope = new paddle::framework::Scope();
```
- 3、 加载模型
```cpp
#include "paddle/fluid/inference/io.h"
auto inference_program = paddle::inference::Load(executor, *scope, dirname);
// or
auto inference_program = paddle::inference::Load(executor,
*scope,
dirname + "/" + model_filename,
dirname + "/" + params_filename);
```
- 4、 获取`feed_target_names``fetch_target_names`
```cpp
const std::vector<std::string>& feed_target_names = inference_program->GetFeedTargetNames();
const std::vector<std::string>& fetch_target_names = inference_program->GetFetchTargetNames();
```
- 5、 准备`feed`数据
```cpp
#include "paddle/fluid/framework/lod_tensor.h"
std::vector<paddle::framework::LoDTensor*> cpu_feeds;
...
std::map<std::string, const paddle::framework::LoDTensor*> feed_targets;
for (size_t i = 0; i < feed_target_names.size(); ++i) {
// Please make sure that cpu_feeds[i] is right for feed_target_names[i]
feed_targets[feed_target_names[i]] = cpu_feeds[i];
}
```
- 6、 定义`Tensor``fetch`结果
```cpp
std::vector<paddle::framework::LoDTensor*> cpu_fetchs;
std::map<std::string, paddle::framework::LoDTensor*> fetch_targets;
for (size_t i = 0; i < fetch_target_names.size(); ++i) {
fetch_targets[fetch_target_names[i]] = cpu_fetchs[i];
}
```
- 7、 执行`inference_program`
```cpp
executor.Run(*inference_program, scope, feed_targets, fetch_targets);
```
- 8、 使用`fetch`数据
```cpp
for (size_t i = 0; i < cpu_fetchs.size(); ++i) {
std::cout << "lod_i: " << cpu_fetchs[i]->lod();
std::cout << "dims_i: " << cpu_fetchs[i]->dims();
std::cout << "result:";
float* output_ptr = cpu_fetchs[i]->data<float>();
for (int j = 0; j < cpu_fetchs[i]->numel(); ++j) {
std::cout << " " << output_ptr[j];
}
std::cout << std::endl;
}
```
针对不同的数据,4. - 8.可执行多次。
- 9、 释放内存
```cpp
delete scope;
```
- 接口说明
```cpp
void Run(const ProgramDesc& program, Scope* scope,
std::map<std::string, const LoDTensor*>& feed_targets,
std::map<std::string, LoDTensor*>& fetch_targets,
bool create_vars = true,
const std::string& feed_holder_name = "feed",
const std::string& fetch_holder_name = "fetch");
```
- 使用Python API `save_inference_model`保存的`program`里面包含了`feed_op``fetch_op`,用户提供的`feed_targets``fetch_targets`必须和`inference_program`中的`feed_op``fetch_op`保持一致。
- 用户提供的`feed_holder_name``fetch_holder_name`也必须和`inference_program``feed_op``fetch_op`保持一致,可使用`SetFeedHolderName``SetFetchHolderName`接口重新设置`inferece_program`
- 默认情况下,除了`persistable`属性设置为`True``Variable`之外,每次执行`executor.Run`会创建一个局部`Scope`,并且在这个局部`Scope`中创建和销毁所有的`Variable`,以最小化空闲时的内存占用。
- `persistable`属性为`True``Variable`有:
- Operators的参数`w``b`
- `feed_op`的输入变量
- `fetch_op`的输出变量
- **不在每次执行时创建和销毁变量
[PR](https://github.com/PaddlePaddle/Paddle/pull/9301)**
- 执行`inference_program`
```cpp
// Call once
executor.CreateVariables(*inference_program, scope, 0);
// Call as many times as you like
executor.Run(
*inference_program, scope, feed_targets, fetch_targets, false);
```
- **优点**
- 节省了频繁创建、销毁变量的时间(约占每次`Run`总时间的1% ~ 12%)
- 执行结束后可获取所有Operators的计算结果
- **缺点**
- 空闲时也会占用大量的内存
- 在同一个`Scope`中,相同的变量名是公用同一块内存的,容易引起意想不到的错误
- **不在每次执行时创建Op [PR](https://github.com/PaddlePaddle/Paddle/pull/9630)**
- 执行`inference_program`
```cpp
// Call once
auto ctx = executor.Prepare(*inference_program, 0);
// Call as many times as you like if you have no need to change the inference_program
executor.RunPreparedContext(ctx.get(), scope, feed_targets, fetch_targets);
```
- **优点**
- 节省了频繁创建、销毁Op的时间
- **缺点**
- 一旦修改了`inference_program`,则需要重新创建`ctx`
- **[多线程共享Parameters](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/test_multi_thread_helper.h)**
- 主线程
- 1、 初始化设备
- 2、 定义`place``executor``scope`
- 3、 加载模型,得到`inference_program`
- 从线程
- **复制`inference_program`得到`copy_program`,修改`copy_program`的`feed_holder_name`和`fetch_holder_name`**
```cpp
auto copy_program = std::unique_ptr<paddle::framework::ProgramDesc>(
new paddle::framework::ProgramDesc(*inference_program));
std::string feed_holder_name = "feed_" + paddle::string::to_string(thread_id);
std::string fetch_holder_name = "fetch_" + paddle::string::to_string(thread_id);
copy_program->SetFeedHolderName(feed_holder_name);
copy_program->SetFetchHolderName(fetch_holder_name);
```
- 4、 获取`copy_program``feed_target_names``fetch_target_names`
- 5、 准备feed数据,定义Tensor来fetch结果
- 6、 执行`copy_program`
```cpp
executor->Run(*copy_program, scope, feed_targets, fetch_targets, true, feed_holder_name, fetch_holder_name);
```
- 7、 使用fetch数据
- 主线程
- 8、 释放资源
- 基本概念
- 数据相关:
- [Tensor](https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/tensor.md),一个N维数组,数据可以是任意类型(int,float,double等)
- [LoDTensor](https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/lod_tensor.md),带LoD(Level-of-Detail)即序列信息的Tensor
- [Scope](https://github.com/PaddlePaddle/Paddle/blob/develop/doc/design/scope.md),记录了变量Variable
- 执行相关:
- [Executor](https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/executor.md),无状态执行器,只跟设备相关
- Place
- CPUPlace,CPU设备
- CUDAPlace,CUDA GPU设备
- 神经网络表示:
- [Program](https://github.com/PaddlePaddle/Paddle/blob/develop/doc/fluid/design/concepts/program.md)
详细介绍请参考[**Paddle Fluid开发者指南**](https://github.com/lcy-seso/learning_notes/blob/master/Fluid/developer's_guid_for_Fluid/Developer's_Guide_to_Paddle_Fluid.md)
## Inference实例
1. fit a line: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_fit_a_line.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_fit_a_line.cc)
1. image classification: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_image_classification.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_image_classification.cc)
1. label semantic roles: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_label_semantic_roles.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_label_semantic_roles.cc)
1. recognize digits: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_recognize_digits.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_recognize_digits.cc)
1. recommender system: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_recommender_system.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_recommender_system.cc)
1. understand sentiment: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_understand_sentiment.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_understand_sentiment.cc)
1. word2vec: [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/tests/book/test_word2vec.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/inference/tests/book/test_inference_word2vec.cc)
## Inference计算优化
- 使用Python推理优化工具[inference_transpiler](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/inference_transpiler.py)
```python
class InferenceTranspiler:
def transpile(self, program, place, scope=None):
...
if scope is None:
scope = global_scope()
...
```
- 使用`InferenceTranspiler`将会直接修改`program`
- 使用`InferenceTranspiler`会修改参数的值,请确保`program`的参数在`scope`内。
- 支持的优化
- 融合batch_norm op的计算
- [使用示例](https://github.com/Xreki/Xreki.github.io/blob/master/fluid/inference/inference_transpiler.py)
```python
import paddle.fluid as fluid
# NOTE: Applying the inference transpiler will change the inference_program.
t = fluid.InferenceTranspiler()
t.transpile(inference_program, place, inference_scope)
```
## 内存使用优化
- 使用Python内存优化工具[memory_optimization_transipiler](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/memory_optimization_transpiler.py)
```python
fluid.memory_optimize(inference_program)
```
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