Skip to content

P
Paddle

PaddlePaddle / Paddle
大约 1 年 前同步成功

通知 2298
Star 20931
Fork 5422
P
Paddle
切换分支/标签
查找文件 普通视图历史永久链接Permalink
csp.html 33.8 KB
Newer Older
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 


<!DOCTYPE html>
<!--[if IE 8]><html class="no-js lt-ie9" lang="en" > <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js" lang="en" > <!--<![endif]-->
<head>
  <meta charset="utf-8">
  
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  
  <title>Design Doc: CSP in PaddlePaddle Fluid &mdash; PaddlePaddle  文档</title>
  

  
  

  

  
  
    

  

  
  
    <link rel="stylesheet" href="../_static/css/theme.css" type="text/css" />
  

  
  
        <link rel="index" title="索引"
              href="../genindex.html"/>
        <link rel="search" title="搜索" href="../search.html"/>
    <link rel="top" title="PaddlePaddle  文档" href="../index.html"/> 

  <link rel="stylesheet" href="https://cdn.jsdelivr.net/perfect-scrollbar/0.6.14/css/perfect-scrollbar.min.css" type="text/css" />
  <link rel="stylesheet" href="../_static/css/override.css" type="text/css" />
  <script>
  var _hmt = _hmt || [];
  (function() {
    var hm = document.createElement("script");
    hm.src = "//hm.baidu.com/hm.js?b9a314ab40d04d805655aab1deee08ba";
    var s = document.getElementsByTagName("script")[0]; 
    s.parentNode.insertBefore(hm, s);
  })();
  </script>

  

  
  <script src="../_static/js/modernizr.min.js"></script>

</head>

<body class="wy-body-for-nav" role="document">

  
  <header class="site-header">
    <div class="site-logo">
      <a href="/"><img src="../_static/images/PP_w.png"></a>
    </div>
    <div class="site-nav-links">
      <div class="site-menu">
        <a class="fork-on-github" href="https://github.com/PaddlePaddle/Paddle" target="_blank"><i class="fa fa-github"></i>Fork me on Github</a>
        <div class="language-switcher dropdown">
          <a type="button" data-toggle="dropdown">
            <span>English</span>
            <i class="fa fa-angle-up"></i>
            <i class="fa fa-angle-down"></i>
          </a>
          <ul class="dropdown-menu">
            <li><a href="/doc_cn">中文</a></li>
            <li><a href="/doc">English</a></li>
          </ul>
        </div>
        <ul class="site-page-links">
          <li><a href="/">Home</a></li>
        </ul>
      </div>
      <div class="doc-module">
        
        <ul>
<li class="toctree-l1"><a class="reference internal" href="../getstarted/index_cn.html">新手入门</a></li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
85 86 87 
<li class="toctree-l1"><a class="reference internal" href="../build_and_install/index_cn.html">安装与编译</a></li>
<li class="toctree-l1"><a class="reference internal" href="../howto/index_cn.html">进阶使用</a></li>
<li class="toctree-l1"><a class="reference internal" href="../dev/index_cn.html">开发标准</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 
<li class="toctree-l1"><a class="reference internal" href="../api/index_cn.html">API</a></li>
<li class="toctree-l1"><a class="reference internal" href="../faq/index_cn.html">FAQ</a></li>
</ul>

        
<div role="search">
  <form id="rtd-search-form" class="wy-form" action="../search.html" method="get">
    <input type="text" name="q" placeholder="Search docs" />
    <input type="hidden" name="check_keywords" value="yes" />
    <input type="hidden" name="area" value="default" />
  </form>
</div>        
      </div>
    </div>
  </header>
  
  <div class="main-content-wrap">

    
    <nav class="doc-menu-vertical" role="navigation">
        
          
          <ul>
<li class="toctree-l1"><a class="reference internal" href="../getstarted/index_cn.html">新手入门</a><ul>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
112 113 
<li class="toctree-l2"><a class="reference internal" href="../getstarted/quickstart_cn.html">快速开始</a></li>
<li class="toctree-l2"><a class="reference internal" href="../getstarted/concepts/use_concepts_cn.html">基本使用概念</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
114 115 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 
<li class="toctree-l1"><a class="reference internal" href="../build_and_install/index_cn.html">安装与编译</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/pip_install_cn.html">使用pip安装</a></li>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/docker_install_cn.html">使用Docker安装运行</a></li>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/build_cn.html">用Docker编译和测试PaddlePaddle</a></li>
<li class="toctree-l2"><a class="reference internal" href="../build_and_install/build_from_source_cn.html">从源码编译</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../howto/index_cn.html">进阶使用</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../howto/cmd_parameter/index_cn.html">命令行参数设置</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/cmd_parameter/use_case_cn.html">使用案例</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cmd_parameter/arguments_cn.html">参数概述</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cmd_parameter/detail_introduction_cn.html">细节描述</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../howto/cluster/index_cn.html">分布式训练</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/cluster/preparations_cn.html">环境准备</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cluster/cmd_argument_cn.html">启动参数说明</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/cluster/multi_cluster/index_cn.html">在不同集群中运行</a><ul>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/fabric_cn.html">使用fabric启动集群训练</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/openmpi_cn.html">在OpenMPI集群中提交训练作业</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/k8s_cn.html">Kubernetes单机训练</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/k8s_distributed_cn.html">Kubernetes分布式训练</a></li>
<li class="toctree-l4"><a class="reference internal" href="../howto/cluster/multi_cluster/k8s_aws_cn.html">Distributed PaddlePaddle Training on AWS with Kubernetes</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
139 140 141 142 
</ul>
</li>
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
143 144 145 146 
<li class="toctree-l2"><a class="reference internal" href="../howto/capi/index_cn.html">C-API预测库</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/capi/compile_paddle_lib_cn.html">安装与编译C-API预测库</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/capi/organization_of_the_inputs_cn.html">输入/输出数据组织</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/capi/workflow_of_capi_cn.html">C-API使用流程</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
147 148 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
149 150 151 152 153 
<li class="toctree-l2"><a class="reference internal" href="../howto/rnn/index_cn.html">RNN相关模型</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/rnn_config_cn.html">RNN配置</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/recurrent_group_cn.html">Recurrent Group教程</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/hierarchical_layer_cn.html">支持双层序列作为输入的Layer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../howto/rnn/hrnn_rnn_api_compare_cn.html">单双层RNN API对比介绍</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
154 155 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
156 
<li class="toctree-l2"><a class="reference internal" href="../howto/optimization/gpu_profiling_cn.html">GPU性能调优</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
157 158 
</ul>
</li>
T
Deploy to GitHub Pages: 7fa1725b04c7f1668e575665c8144225ad8d97a4  
Travis CI 已提交
159 160 161 
<li class="toctree-l1"><a class="reference internal" href="../dev/index_cn.html">开发标准</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../dev/contribute_to_paddle_cn.html">如何贡献代码</a></li>
<li class="toctree-l2"><a class="reference internal" href="../dev/write_docs_cn.html">如何贡献文档</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../api/index_cn.html">API</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../api/v2/model_configs.html">模型配置</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/activation.html">Activation</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/layer.html">Layers</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/evaluators.html">Evaluators</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/optimizer.html">Optimizer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/pooling.html">Pooling</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/networks.html">Networks</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/config/attr.html">Parameter Attribute</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../api/v2/data.html">数据访问</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/data/data_reader.html">Data Reader Interface</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/data/image.html">Image Interface</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/data/dataset.html">Dataset</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../api/v2/run_logic.html">训练与应用</a></li>
<li class="toctree-l2"><a class="reference internal" href="../api/v2/fluid.html">Fluid</a><ul>
T
Deploy to GitHub Pages: 43262608442a7c3f11422d7a87c0be68ac3293d8  
Travis CI 已提交
183 184 185 186 187 188 189 190 191 192 193 
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/layers.html">layers</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/data_feeder.html">data_feeder</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/executor.html">executor</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/initializer.html">initializer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/evaluator.html">evaluator</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/nets.html">nets</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/optimizer.html">optimizer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/param_attr.html">param_attr</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/profiler.html">profiler</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/regularizer.html">regularizer</a></li>
<li class="toctree-l3"><a class="reference internal" href="../api/v2/fluid/io.html">io</a></li>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../faq/index_cn.html">FAQ</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../faq/build_and_install/index_cn.html">编译安装与单元测试</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/model/index_cn.html">模型配置</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/parameter/index_cn.html">参数设置</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/local/index_cn.html">本地训练与预测</a></li>
<li class="toctree-l2"><a class="reference internal" href="../faq/cluster/index_cn.html">集群训练与预测</a></li>
</ul>
</li>
</ul>

        
    </nav>
    
    <section class="doc-content-wrap">

      

 







<div role="navigation" aria-label="breadcrumbs navigation">
  <ul class="wy-breadcrumbs">
      
    <li>Design Doc: CSP in PaddlePaddle Fluid</li>
  </ul>
</div>
      
      <div class="wy-nav-content" id="doc-content">
        <div class="rst-content">
          <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
           <div itemprop="articleBody">
            
  <div class="section" id="design-doc-csp-in-paddlepaddle-fluid">
<span id="design-doc-csp-in-paddlepaddle-fluid"></span><h1>Design Doc: CSP in PaddlePaddle Fluid<a class="headerlink" href="#design-doc-csp-in-paddlepaddle-fluid" title="永久链接至标题"></a></h1>
<div class="section" id="motivation">
<span id="motivation"></span><h2>Motivation<a class="headerlink" href="#motivation" title="永久链接至标题"></a></h2>
<p>Concurrent programming is important for deep learning.  Few example applications are:</p>
<ol class="simple">
<li>The main thread keeps reading the next mini-batch while another thread uses the GPU for computing.</li>
<li>The main thread performs the computation while another thread uploads the local gradients from each trainer to the parameter server.</li>
</ol>
<p>Most DL systems, including TensorFlow, Caffe2, and MxNet, can asynchronously execute operators in a graph. However, Fluid doesn&#8217;t have the concept of a graph at all, as the design goal of Fluid is that of a programming language.</p>
</div>
<div class="section" id="concurrent-programming-models">
<span id="concurrent-programming-models"></span><h2>Concurrent Programming Models<a class="headerlink" href="#concurrent-programming-models" title="永久链接至标题"></a></h2>
<p>There were many concurrent programming models, implemented in various forms:</p>
<p>| concurrent programming model | implementation |
|&#8212;&#8211;|&#8212;&#8211;|
| mutex | types and functions in standard libraries |
| semaphore | types and functions in standard libraries |
| communicating sequential processes (CSP) | Go programming language |
| actor model | Erlang programming language |
| message passing | MPI |
| bulk synchronous parallel (BSP) | Pregel distributed programming framework |</p>
<p>Since Fluid was designed to be a programming language, we would like to implement CSP in Fluid.</p>
<div class="section" id="csp-v-s-actor-model">
<span id="csp-v-s-actor-model"></span><h3>CSP v.s. Actor Model<a class="headerlink" href="#csp-v-s-actor-model" title="永久链接至标题"></a></h3>
<p>A well-known implementation of Actor Model is the Erlang programming language.  In Actor Model, <em>processes</em> could send messages to another process and receive messages from another process given the process IDs.  We can find the three ingredients, process with ID, send, and recv, in MPI too.  Indeed, we can rewrite Erlang programs in Python + MPI with possibly fewer lines of code.  Our concern with Actor Model is that it doesn&#8217;t seem reasonable to implement process management in a programming language&#8217;s runtime library; instead, it should be the operating systems&#8217; responsibility to manage processes and libraries like MPI for send/recv.</p>
</div>
</div>
<div class="section" id="csp-in-fluid">
<span id="csp-in-fluid"></span><h2>CSP in Fluid<a class="headerlink" href="#csp-in-fluid" title="永久链接至标题"></a></h2>
<p>Fluid has two fundamental control-flows: <em>if-else</em> and <em>while</em>.  If we are to implement CSP, we need the following:</p>
<ol class="simple">
<li>a new data type: <em>channel</em> and operators <em>send</em> and <em>recv</em>,</li>
<li><em>goroutine</em> or thread, and</li>
<li>a new control-flow: select.</li>
</ol>
<p>We also need Python wrappers for the above components.</p>
<p>The type <em>channel</em> is conceptually the blocking queue.  In Go, its implemented is a <a class="reference external" href="https://github.com/golang/go/blob/68ce117cf17b8debf5754bfd476345779b5b6616/src/runtime/chan.go#L31-L50">blocking circular queue</a>, which supports send and recv.</p>
<p>The <code class="docutils literal"><span class="pre">select</span></code> operation has been in OS kernels long before Go language.  All Unix kernels implement system calls <em>poll</em> and <em>select</em>.  They monitor multiple file descriptors to see if I/O is possible on any of them.  This takes O(N) time.  Since Linux 2.6, a new system call, <em>epoll</em>, can do the same in O(1) time.  In BSD systems, there is a similar system call <em>kqueue</em>.  Go&#8217;s Linux implementation uses epoll.</p>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
274 
<p>It might be a good idea to implement Fluid&#8217;s select using epoll too.  In this design doc, we start from the O(N) way so that we could focus on Python binding and the syntax.</p>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 
<div class="section" id="type-channel">
<span id="type-channel"></span><h3>Type Channel<a class="headerlink" href="#type-channel" title="永久链接至标题"></a></h3>
<p>Fluid supports many data types:</p>
<ol class="simple">
<li>Tensor,</li>
<li>Row-sparse Tensor</li>
<li>LoD Tensor,</li>
<li>Tensor array, etc</li>
</ol>
<p>Each data type is registered in the <a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/framework/framework.proto#L117-L127"><code class="docutils literal"><span class="pre">framework.proto</span></code></a> as an enum value.  To add a new type channel, we need to add a new type enum.</p>
<p>To expose a C++ type to Python, we need to edit the <a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/pybind/pybind.cc"><code class="docutils literal"><span class="pre">pybind.cc</span></code></a> file.  <a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/pybind/pybind.cc#L120-L164">Here</a> is an example how we expose C++ class LoDTensor.</p>
</div>
</div>
<div class="section" id="syntax-design">
<span id="syntax-design"></span><h2>Syntax Design<a class="headerlink" href="#syntax-design" title="永久链接至标题"></a></h2>
<div class="section" id="create-channel">
<span id="create-channel"></span><h3>Create Channel<a class="headerlink" href="#create-channel" title="永久链接至标题"></a></h3>
<p>In Go, we create a channel by specifying the element type and buffer size:</p>
<div class="highlight-go"><div class="highlight"><pre><span></span><span class="nx">ch</span>  <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">)</span>       <span class="c1">// a channel without buffer</span>
<span class="nx">ch1</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>  <span class="c1">// a channel that can buffer 100 ints.</span>
</pre></div>
</div>
<p>In Fluid, we should be able to do the same:</p>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
298 299 
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">ch</span>  <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_channel</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">INT</span><span class="p">)</span>
<span class="n">ch1</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_channel</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">INT</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
300 301 302 
</pre></div>
</div>
<p>In addition to that, we want channels that can hold more complex element types, e.g., Tensors of float16:</p>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
303 
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">ch</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_channel</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">Tensor</span><span class="p">,</span> <span class="n">etype</span><span class="o">=</span><span class="n">float16</span><span class="p">)</span>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
304 305 306 307 308 309 310 
</pre></div>
</div>
<p>or Tensors of Tensors of float16 etc.</p>
<p>The point here is that we need a consistent way to compose types, like in C++ we can have <code class="docutils literal"><span class="pre">Tensor&lt;Tensor&lt;...&lt;float16&gt;...&gt;</span> <span class="pre">&gt;</span></code>.</p>
</div>
<div class="section" id="send-and-recv">
<span id="send-and-recv"></span><h3>Send and Recv<a class="headerlink" href="#send-and-recv" title="永久链接至标题"></a></h3>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
311 312 313 314 315 316 317 318 319 320 
<p>Go&#8217;s CSP implementation depends on data type <em>channel</em>. There are two types of channels:</p>
<ol class="simple">
<li>The unblocked channel, or buffered channel, is a blocking queue with a non-zero sized buffer. The sending to buffered channel blocks if the buffer is full, and the receive operation blocks if the buffer is empty.</li>
<li>blocked channel, or unbuffered channel, is a blocking queue with no buffer.  Both sending and receiving block with unbuffered channels.</li>
</ol>
<p>There are four types of actions with a channel:</p>
<ol>
<li><p class="first">Create a channel</p>
<div class="highlight-go"><div class="highlight"><pre><span></span><span class="nx">ch</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">)</span> <span class="c1">// this is an unbuffered channel</span>
<span class="nx">ch</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span> <span class="c1">// this is a buffered channel of 100 ints.</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
321 322 
</pre></div>
</div>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
323 324 325 
</li>
<li><p class="first">Send</p>
<div class="highlight-go"><div class="highlight"><pre><span></span><span class="nx">ch</span> <span class="o">&lt;-</span> <span class="mi">111</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
326 327 
</pre></div>
</div>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
328 329 330 
</li>
<li><p class="first">Recv</p>
<div class="highlight-go"><div class="highlight"><pre><span></span><span class="nx">y</span><span class="p">,</span> <span class="nx">ok</span> <span class="o">&lt;-</span> <span class="nx">ch</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
331 332 
</pre></div>
</div>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 
</li>
<li><p class="first">Close</p>
<div class="highlight-go"><div class="highlight"><pre><span></span><span class="nb">close</span><span class="p">(</span><span class="nx">ch</span><span class="p">)</span>
</pre></div>
</div>
<p>Please be aware that a closed channel is not a nil channel, which is <code class="docutils literal"><span class="pre">var</span> <span class="pre">ch</span> <span class="pre">chan</span> <span class="pre">int</span></code>.</p>
</li>
</ol>
<p>There are some <a class="reference external" href="https://dave.cheney.net/2014/03/19/channel-axioms">axioms with channels</a>:</p>
<ol class="simple">
<li>A send to a nil channel blocks forever</li>
<li>A receive from a nil channel blocks forever</li>
<li>A send to a closed channel panics</li>
<li>A receive from a closed channel returns the residual values and then zeros.</li>
</ol>
<p>In Fluid, we have <a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/framework/details/buffered_channel.h">buffered channels</a> and <a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/framework/details/unbuffered_channel.h">unbuffered channels</a></p>
<p>The following program illustrates the Python syntax for accessing Fluid buffers.</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">fluid</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
351
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
352 
<span class="n">buffer_size</span> <span class="o">=</span> <span class="mi">10</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
353 354 355 
<span class="n">ch</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_channel</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">INT</span><span class="p">,</span> <span class="n">buffer_size</span><span class="p">)</span>

<span class="c1"># Now write three elements to the channel</span>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
356 357 
<span class="k">with</span> <span class="n">fluid</span><span class="o">.</span><span class="k">while</span><span class="p">(</span><span class="n">steps</span><span class="o">=</span><span class="n">buffer_size</span><span class="p">):</span>
  <span class="n">fluid</span><span class="o">.</span><span class="n">send</span><span class="p">(</span><span class="n">ch</span><span class="p">,</span> <span class="n">step</span><span class="p">)</span>
T
Deploy to GitHub Pages: 6024a170f321e3ed572260e68cad39820f15ff67  
Travis CI 已提交
358 359 360 

<span class="n">fluid</span><span class="o">.</span><span class="n">close_channel</span><span class="p">(</span><span class="n">ch</span><span class="p">)</span>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
361 362 
<span class="k">with</span> <span class="n">fluid</span><span class="o">.</span><span class="k">while</span><span class="p">(</span><span class="n">steps</span><span class="o">=</span><span class="n">buffer_size</span><span class="p">):</span>
  <span class="n">fluid</span><span class="o">.</span><span class="k">print</span><span class="p">(</span><span class="n">fluid</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="n">ch</span><span class="p">))</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
363 364 
</pre></div>
</div>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
365 366 
<p>The following example shows that to avoid the always-blocking behavior of unbuffered channels, we need to use Fluid&#8217;s goroutines.</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">fluid</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
367 368 369 

<span class="n">ch</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_channel</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">INT</span><span class="p">)</span>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
370 371 
<span class="k">with</span> <span class="n">fluid</span><span class="o">.</span><span class="n">go</span><span class="p">():</span>
  <span class="n">fluid</span><span class="o">.</span><span class="n">send</span><span class="p">(</span><span class="n">ch</span><span class="p">)</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
372
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
373 
<span class="n">y</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">recv</span><span class="p">(</span><span class="n">ch</span><span class="p">)</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
374
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
375 
<span class="n">fluid</span><span class="o">.</span><span class="n">close_channel</span><span class="p">(</span><span class="n">ch</span><span class="p">)</span>
T
Deploy to GitHub Pages: 497a131e53316fc3d81cf92e68845d2fd33243e3  
Travis CI 已提交
376 377 
</pre></div>
</div>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
378 379 380 
</div>
<div class="section" id="select">
<span id="select"></span><h3>Select<a class="headerlink" href="#select" title="永久链接至标题"></a></h3>
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
381 
<p>In Go, the <code class="docutils literal"><span class="pre">select</span></code> statement lets a goroutine wait on multiple communication operations. A <code class="docutils literal"><span class="pre">select</span></code> blocks until one of its cases can run, then it executes that case. It chooses one at random if multiple are ready.</p>
T
Deploy to GitHub Pages: 1ead6c2691be09f34303c06d119c17ba4e4aeab7  
Travis CI 已提交
382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 
<div class="highlight-go"><div class="highlight"><pre><span></span><span class="nx">ch1</span>  <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">)</span>       
<span class="nx">ch2</span>  <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>

<span class="nx">x</span> <span class="o">:=</span> <span class="mi">0</span>

<span class="k">for</span> <span class="p">{</span>
    <span class="k">select</span> <span class="p">{</span>
    <span class="k">case</span> <span class="nx">ch1</span> <span class="o">&lt;-</span> <span class="nx">x</span><span class="p">:</span>
      <span class="nx">x</span> <span class="o">:=</span> <span class="nx">x</span> <span class="o">+</span> <span class="mi">1</span>
    <span class="k">case</span> <span class="nx">y</span> <span class="o">&lt;-</span> <span class="nx">ch2</span><span class="p">:</span>
      <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;Received on channel&quot;</span><span class="p">)</span>
    <span class="k">default</span><span class="p">:</span>
      <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">&quot;Default&quot;</span><span class="p">)</span>
    <span class="p">}</span>
  <span class="p">}</span>
</pre></div>
</div>
<p>In Fluid, we should be able to do the same:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">ch1</span>  <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_chan</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">INT</span><span class="p">)</span>
<span class="n">ch2</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">make_chan</span><span class="p">(</span><span class="n">dtype</span><span class="o">=</span><span class="n">INT</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>

<span class="n">sel</span> <span class="o">=</span> <span class="n">fluid</span><span class="o">.</span><span class="n">select</span><span class="p">()</span>

<span class="k">with</span> <span class="n">sel</span><span class="o">.</span><span class="n">case</span><span class="p">(</span><span class="n">ch1</span><span class="p">,</span> <span class="s1">&#39;w&#39;</span><span class="p">,</span> <span class="n">X</span><span class="p">):</span>
    <span class="n">fluid</span><span class="o">.</span><span class="n">layers</span><span class="o">.</span><span class="n">increment</span><span class="p">(</span><span class="n">X</span><span class="p">)</span>

<span class="k">with</span> <span class="n">sel</span><span class="o">.</span><span class="n">case</span><span class="p">(</span><span class="n">ch2</span><span class="p">,</span> <span class="s1">&#39;r&#39;</span><span class="p">,</span> <span class="n">Y</span><span class="p">):</span>
    <span class="n">fluid</span><span class="o">.</span><span class="k">print</span><span class="p">(</span><span class="s2">&quot;Received on Channel&quot;</span><span class="p">)</span>

<span class="k">with</span> <span class="n">sel</span><span class="o">.</span><span class="n">default</span><span class="p">():</span>
    <span class="n">fluid</span><span class="o">.</span><span class="k">print</span><span class="p">(</span><span class="s2">&quot;Default&quot;</span><span class="p">)</span>

</pre></div>
</div>
<p>In the above code snippet, <code class="docutils literal"><span class="pre">X</span></code> and <code class="docutils literal"><span class="pre">Y</span></code> are variables. Now let us look at each of these statements one by one.</p>
<ul class="simple">
T
Deploy to GitHub Pages: b0ecb36583ed97737bd5c43cbafbdc8fa29cbd68  
Travis CI 已提交
418 419 
<li><code class="docutils literal"><span class="pre">sel.case(ch1,</span> <span class="pre">'w',</span> <span class="pre">X)</span></code> : This specifies that we are writing to <code class="docutils literal"><span class="pre">ch1</span></code> and we want to write the integer in variable <code class="docutils literal"><span class="pre">X</span></code> to the channel. The character <code class="docutils literal"><span class="pre">w</span></code> is used here to make the syntax familiar to write syntax in Python I/O.</li>
<li><code class="docutils literal"><span class="pre">sel.case(ch2,</span> <span class="pre">'r',</span> <span class="pre">Y)</span></code> : This specifies that we would like to read the result from <code class="docutils literal"><span class="pre">ch2</span></code> into variable <code class="docutils literal"><span class="pre">Y</span></code>. The character <code class="docutils literal"><span class="pre">r</span></code> is used here to make the syntax familiar to read syntax in Python I/O.</li>
T
Deploy to GitHub Pages: 1ead6c2691be09f34303c06d119c17ba4e4aeab7  
Travis CI 已提交
420 421 
<li><code class="docutils literal"><span class="pre">sel.default()</span></code> : This is equivalent to the default in Go <code class="docutils literal"><span class="pre">select</span></code>. If none of the channels are ready for read or write, then the fluid code in the default block will be executed.</li>
</ul>
T
Deploy to GitHub Pages: 7ccbc706bf745bc91a11b13001e82092060f83c5  
Travis CI 已提交
422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 
</div>
</div>
<div class="section" id="example-programs">
<span id="example-programs"></span><h2>Example Programs<a class="headerlink" href="#example-programs" title="永久链接至标题"></a></h2>
<div class="section" id="rpc-between-trainers-and-parameter-servers">
<span id="rpc-between-trainers-and-parameter-servers"></span><h3>1. RPC between Trainers and Parameter Servers<a class="headerlink" href="#rpc-between-trainers-and-parameter-servers" title="永久链接至标题"></a></h3>
</div>
<div class="section" id="concurrent-minibatch-loading">
<span id="concurrent-minibatch-loading"></span><h3>2. Concurrent Minibatch Loading<a class="headerlink" href="#concurrent-minibatch-loading" title="永久链接至标题"></a></h3>
</div>
</div>
</div>


           </div>
          </div>
          <footer>
  

  <hr/>

  <div role="contentinfo">
    <p>
        &copy; Copyright 2016, PaddlePaddle developers.

    </p>
  </div>
  Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>. 

</footer>

        </div>
      </div>

    </section>

  </div>
  


  

    <script type="text/javascript">
        var DOCUMENTATION_OPTIONS = {
            URL_ROOT:'../',
            VERSION:'',
            COLLAPSE_INDEX:false,
            FILE_SUFFIX:'.html',
            HAS_SOURCE:  true,
            SOURCELINK_SUFFIX: ".txt",
        };
    </script>
      <script type="text/javascript" src="../_static/jquery.js"></script>
      <script type="text/javascript" src="../_static/underscore.js"></script>
      <script type="text/javascript" src="../_static/doctools.js"></script>
      <script type="text/javascript" src="../_static/translations.js"></script>
      <script type="text/javascript" src="https://cdn.bootcss.com/mathjax/2.7.0/MathJax.js"></script>
       
  

  
  
    <script type="text/javascript" src="../_static/js/theme.js"></script>
  
  
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>
  <script src="https://cdn.jsdelivr.net/perfect-scrollbar/0.6.14/js/perfect-scrollbar.jquery.min.js"></script>
  <script src="../_static/js/paddle_doc_init.js"></script> 

</body>
</html>