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
large_model_dist_train.html 23.8 KB
Newer Older
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
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 85 86 


<!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>Alalysis of large model distributed training in Paddle &mdash; PaddlePaddle  documentation</title>
  

  
  

  

  
  
    

  

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

  
  
        <link rel="index" title="Index"
              href="../../genindex.html"/>
        <link rel="search" title="Search" href="../../search.html"/>
    <link rel="top" title="PaddlePaddle  documentation" 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_en.html">GET STARTED</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../howto/index_en.html">HOW TO</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../api/index_en.html">API</a></li>
T
Deploy to GitHub Pages: 664691c89af182de3919fc72a7c875311e03893d  
Travis CI 已提交
87 
<li class="toctree-l1"><a class="reference internal" href="../../mobile/index_en.html">MOBILE</a></li>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
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 
</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_en.html">GET STARTED</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../../getstarted/build_and_install/index_en.html">Install and Build</a><ul>
T
Deploy to GitHub Pages: 0c0ff2828ccedb51db23290d6df9e4c83839d6af  
Travis CI 已提交
111 112 
<li class="toctree-l3"><a class="reference internal" href="../../getstarted/build_and_install/pip_install_en.html">Install Using pip</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../getstarted/build_and_install/docker_install_en.html">Run in Docker Containers</a></li>
T
Deploy to GitHub Pages: 458ffbf4fe7fe6da5e2ea133c027d560815cc3cc  
Travis CI 已提交
113 
<li class="toctree-l3"><a class="reference internal" href="../../howto/dev/build_en.html">Build using Docker</a></li>
T
Deploy to GitHub Pages: 0c0ff2828ccedb51db23290d6df9e4c83839d6af  
Travis CI 已提交
114 
<li class="toctree-l3"><a class="reference internal" href="../../getstarted/build_and_install/build_from_source_en.html">Build from Sources</a></li>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
Travis CI 已提交
115 116 117 118 119 120 121 122 123 124 125 
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../../howto/index_en.html">HOW TO</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../../howto/usage/cmd_parameter/index_en.html">Set Command-line Parameters</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/usage/cmd_parameter/use_case_en.html">Use Case</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/usage/cmd_parameter/arguments_en.html">Argument Outline</a></li>
<li class="toctree-l3"><a class="reference internal" href="../../howto/usage/cmd_parameter/detail_introduction_en.html">Detail Description</a></li>
</ul>
</li>
T
Deploy to GitHub Pages: 63ffe5250a120ff430469b8d000deb2b031c4881  
Travis CI 已提交
126 
<li class="toctree-l2"><a class="reference internal" href="../../howto/usage/cluster/cluster_train_en.html">PaddlePaddle Distributed Training</a></li>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
Travis CI 已提交
127 
<li class="toctree-l2"><a class="reference internal" href="../../howto/dev/new_layer_en.html">Write New Layers</a></li>
T
Deploy to GitHub Pages: f122a5da2f27038b48f6ed607e296d762050e920  
Travis CI 已提交
128 
<li class="toctree-l2"><a class="reference internal" href="../../howto/dev/contribute_to_paddle_en.html">Contribute Code</a></li>
T
Deploy to GitHub Pages: 70ee79c2567d5128a9d527b444fcee30f83c02a5  
Travis CI 已提交
129 
<li class="toctree-l2"><a class="reference internal" href="../../howto/dev/write_docs_en.html">Contribute Documentation</a></li>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
Travis CI 已提交
130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 
<li class="toctree-l2"><a class="reference internal" href="../../howto/deep_model/rnn/index_en.html">RNN Models</a><ul>
<li class="toctree-l3"><a class="reference internal" href="../../howto/deep_model/rnn/rnn_config_en.html">RNN Configuration</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="../../howto/optimization/gpu_profiling_en.html">Tune GPU Performance</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../../api/index_en.html">API</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../../api/v2/model_configs.html">Model Configuration</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>
T
Deploy to GitHub Pages: d4d8f742a3bc4366bf410bc9ff29c0c32666bf60  
Travis CI 已提交
148 149 150 151 152 153 
<li class="toctree-l2"><a class="reference internal" href="../../api/v2/data.html">Data Reader Interface and DataSets</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>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
Travis CI 已提交
154 
<li class="toctree-l2"><a class="reference internal" href="../../api/v2/run_logic.html">Training and Inference</a></li>
T
Deploy to GitHub Pages: 1fe05c458fa1d7ff1949759c2a06ed6d19ab8048  
Travis CI 已提交
155 156 157 158 159 160 161 162 163 164 165 166 167 
<li class="toctree-l2"><a class="reference internal" href="../../api/v2/fluid.html">Fluid</a><ul>
<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">DataFeeder</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">ParamAttr</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>
</ul>
</li>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
Travis CI 已提交
168 169 
</ul>
</li>
T
Deploy to GitHub Pages: 664691c89af182de3919fc72a7c875311e03893d  
Travis CI 已提交
170 171 
<li class="toctree-l1"><a class="reference internal" href="../../mobile/index_en.html">MOBILE</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../../mobile/cross_compiling_for_android_en.html">Build PaddlePaddle for Android</a></li>
T
Deploy to GitHub Pages: 78c20e3ed3ca9c03239292ec1c3769697dc976c4  
Travis CI 已提交
172 
<li class="toctree-l2"><a class="reference internal" href="../../mobile/cross_compiling_for_ios_en.html">PaddlePaddle Compiling Guide for iOS</a></li>
T
Deploy to GitHub Pages: 664691c89af182de3919fc72a7c875311e03893d  
Travis CI 已提交
173 174 175 
<li class="toctree-l2"><a class="reference internal" href="../../mobile/cross_compiling_for_raspberry_en.html">Build PaddlePaddle for Raspberry Pi</a></li>
</ul>
</li>
T
Deploy to GitHub Pages: d08550fdd22453227e9a3f3f5e061c2849290304  
Travis CI 已提交
176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 
</ul>

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

      

 







<div role="navigation" aria-label="breadcrumbs navigation">
  <ul class="wy-breadcrumbs">
      
    <li>Alalysis of large model distributed training in Paddle</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="alalysis-of-large-model-distributed-training-in-paddle">
<span id="alalysis-of-large-model-distributed-training-in-paddle"></span><h1>Alalysis of large model distributed training in Paddle<a class="headerlink" href="#alalysis-of-large-model-distributed-training-in-paddle" title="Permalink to this headline"></a></h1>
<p><strong><em>NOTE: This is only some note for how we implemeted this scheme in V1, not a new design.</em></strong></p>
<div class="section" id="what-is-it">
<span id="what-is-it"></span><h2>What is it<a class="headerlink" href="#what-is-it" title="Permalink to this headline"></a></h2>
<p>We often encounter cases that the embedding layer parameters(sparse) are so large that we can not store it in the trainer&#8217;s memory when training. So we need to put them to several servers, and fetch them row by row instead of fetch all of the parameters.</p>
</div>
<div class="section" id="how-to-use">
<span id="how-to-use"></span><h2>How to use<a class="headerlink" href="#how-to-use" title="Permalink to this headline"></a></h2>
<p>Specify command-line argument like  <code class="docutils literal"><span class="pre">--loadsave_parameters_in_pserver=true</span> <span class="pre">--ports_num_for_sparse=1</span> <span class="pre">--use_old_updater=1</span></code> when starting the paddle trainer. And also add something like <code class="docutils literal"><span class="pre">--ports_num_for_sparse=1</span> <span class="pre">--pserver_num_threads=5</span></code> when starting pserver processes.</p>
<p>Accrodingly, configure your embedding layers like:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">SPARSE_REMOTE</span><span class="o">=</span><span class="bp">True</span>

<span class="n">w1</span> <span class="o">=</span> <span class="n">data_layer</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s2">&quot;w1&quot;</span><span class="p">,</span> <span class="n">size</span><span class="o">=</span><span class="n">dict_size</span><span class="p">)</span>
<span class="n">emb1</span> <span class="o">=</span> <span class="n">embedding_layer</span><span class="p">(</span><span class="nb">input</span><span class="o">=</span><span class="n">w1</span><span class="p">,</span> <span class="n">size</span><span class="o">=</span><span class="mi">32</span><span class="p">,</span> <span class="n">param_attr</span><span class="o">=</span><span class="n">ParameterAttribute</span><span class="p">(</span><span class="n">sparse_update</span><span class="o">=</span><span class="n">SPARSE_REMOTE</span><span class="p">))</span>
<span class="n">w2</span> <span class="o">=</span> <span class="n">data_layer</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s2">&quot;w2&quot;</span><span class="p">,</span> <span class="n">size</span><span class="o">=</span><span class="n">dict_size</span><span class="p">)</span>
<span class="n">emb2</span> <span class="o">=</span> <span class="n">embedding_layer</span><span class="p">(</span><span class="nb">input</span><span class="o">=</span><span class="n">w2</span><span class="p">,</span> <span class="n">size</span><span class="o">=</span><span class="mi">32</span><span class="p">,</span> <span class="n">param_attr</span><span class="o">=</span><span class="n">ParameterAttribute</span><span class="p">(</span><span class="n">sparse_update</span><span class="o">=</span><span class="n">SPARSE_REMOTE</span><span class="p">))</span>
<span class="o">...</span>
</pre></div>
</div>
</div>
<div class="section" id="implementation-details">
<span id="implementation-details"></span><h2>Implementation details<a class="headerlink" href="#implementation-details" title="Permalink to this headline"></a></h2>
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="k">enum</span> <span class="n">MatType</span> <span class="p">{</span>
  <span class="n">MAT_NORMAL</span><span class="p">,</span>
  <span class="n">MAT_NORMAL_SHARED</span><span class="p">,</span>
  <span class="n">MAT_VALUE_SHARED</span><span class="p">,</span>
  <span class="n">MAT_SPARSE_ROW_IDS</span><span class="p">,</span>
  <span class="n">MAT_SPARSE_ROW_AUTO_GROW</span><span class="p">,</span>
  <span class="n">MAT_CACHE_ROW</span><span class="p">,</span>
  <span class="n">MAT_SPARSE_ROW</span><span class="p">,</span>
  <span class="n">MAT_SPARSE_ROW_PREFETCH</span><span class="p">,</span>
  <span class="n">MAT_SPARSE_ROW_PREFETCH_FULL_SIZE</span><span class="p">,</span>
<span class="p">};</span>
</pre></div>
</div>
<p><code class="docutils literal"><span class="pre">MAT_SPARSE_ROW_PREFETCH</span></code> is what we use when configured to fetch only row of matrix when training.</p>
<p>In <code class="docutils literal"><span class="pre">trainer_internal.cpp:L93</span> <span class="pre">trainOneBatch</span></code>:</p>
<div class="highlight-c++"><div class="highlight"><pre><span></span>  <span class="k">if</span> <span class="p">(</span><span class="n">config_</span><span class="o">-&gt;</span><span class="n">getOptConfig</span><span class="p">().</span><span class="n">use_sparse_remote_updater</span><span class="p">())</span> <span class="p">{</span>
    <span class="n">REGISTER_TIMER</span><span class="p">(</span><span class="s">&quot;prefetch&quot;</span><span class="p">);</span>
    <span class="n">gradientMachine_</span><span class="o">-&gt;</span><span class="n">prefetch</span><span class="p">(</span><span class="n">inArgs</span><span class="p">);</span>
    <span class="n">parameterUpdater_</span><span class="o">-&gt;</span><span class="n">getParametersRemote</span><span class="p">();</span>
  <span class="p">}</span>
</pre></div>
</div>
<p>When doing actual network forward and backward, at the beginning of each batch, the trainer will try to download one row of data from pserver.</p>
<p>In <code class="docutils literal"><span class="pre">trainer/RemoteParameterUpdater.cpp</span></code>: <code class="docutils literal"><span class="pre">parameterUpdater_-&gt;getParametersRemote();</span></code>:</p>
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="n">fullSize</span><span class="p">)</span> <span class="p">{</span>
    <span class="p">...</span>
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
<span class="n">getParams</span> <span class="o">=</span> <span class="p">[</span><span class="o">&amp;</span><span class="p">]</span> <span class="p">{</span>
    <span class="n">parameterClient_</span><span class="o">-&gt;</span><span class="n">getParameterSparse</span><span class="p">(</span>
        <span class="cm">/* recvParameterType= */</span> <span class="n">PARAMETER_VALUE</span><span class="p">,</span> <span class="n">sendBackParameterType</span><span class="p">);</span>
<span class="p">};</span>
<span class="n">applyL1</span> <span class="o">=</span> <span class="p">[](</span><span class="n">Parameter</span><span class="o">&amp;</span> <span class="n">para</span><span class="p">,</span> <span class="n">real</span> <span class="n">decayRate</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">para</span><span class="p">.</span><span class="n">getMat</span><span class="p">(</span><span class="n">PARAMETER_VALUE</span><span class="p">)</span><span class="o">-&gt;</span><span class="n">applyL1</span><span class="p">(</span><span class="cm">/*lr=*/</span><span class="mf">1.0f</span><span class="p">,</span> <span class="n">decayRate</span><span class="p">);</span>
<span class="p">};</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Calling <code class="docutils literal"><span class="pre">parameterClient_-&gt;getParameterSparse</span></code> will do remote call to pserver&#8217;s <code class="docutils literal"><span class="pre">getParameterSparse</span></code>:</p>
<div class="highlight-c++"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="n">ParameterServer2</span><span class="o">::</span><span class="n">getParameterSparse</span><span class="p">(</span><span class="k">const</span> <span class="n">SendParameterRequest</span><span class="o">&amp;</span> <span class="n">request</span><span class="p">,</span>
                                          <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">Buffer</span><span class="o">&gt;&amp;</span> <span class="n">inputBuffers</span><span class="p">,</span>
                                          <span class="n">SendParameterResponse</span><span class="o">*</span> <span class="n">response</span><span class="p">,</span>
                                          <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">Buffer</span><span class="o">&gt;*</span> <span class="n">outputBuffers</span><span class="p">)</span> <span class="p">{</span>
  <span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="n">inputBuffers</span><span class="p">;</span>
  <span class="k">auto</span><span class="o">&amp;</span> <span class="n">buffer</span> <span class="o">=</span> <span class="o">*</span><span class="n">readWriteBuffer_</span><span class="p">;</span>
  <span class="kt">size_t</span> <span class="n">numReals</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
  <span class="k">for</span> <span class="p">(</span><span class="k">const</span> <span class="k">auto</span><span class="o">&amp;</span> <span class="nl">block</span> <span class="p">:</span> <span class="n">request</span><span class="p">.</span><span class="n">blocks</span><span class="p">())</span> <span class="p">{</span>
    <span class="n">numReals</span> <span class="o">+=</span> <span class="n">getParameterConfig</span><span class="p">(</span><span class="n">block</span><span class="p">).</span><span class="n">dims</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span>
  <span class="p">}</span>
  <span class="n">buffer</span><span class="p">.</span><span class="n">resize</span><span class="p">(</span><span class="n">numReals</span><span class="p">);</span>

  <span class="n">VLOG</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;pserver: getParameterSparse, numReals=&quot;</span> <span class="o">&lt;&lt;</span> <span class="n">numReals</span><span class="p">;</span>

  <span class="n">ReadLockGuard</span> <span class="nf">guard</span><span class="p">(</span><span class="n">parameterMutex_</span><span class="p">);</span>
  <span class="kt">size_t</span> <span class="n">offset</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
  <span class="k">for</span> <span class="p">(</span><span class="k">const</span> <span class="k">auto</span><span class="o">&amp;</span> <span class="nl">block</span> <span class="p">:</span> <span class="n">request</span><span class="p">.</span><span class="n">blocks</span><span class="p">())</span> <span class="p">{</span>
    <span class="kt">size_t</span> <span class="n">width</span> <span class="o">=</span> <span class="n">getParameterConfig</span><span class="p">(</span><span class="n">block</span><span class="p">).</span><span class="n">dims</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span>
    <span class="n">Buffer</span> <span class="n">buf</span> <span class="o">=</span> <span class="p">{</span><span class="n">buffer</span><span class="p">.</span><span class="n">data</span><span class="p">()</span> <span class="o">+</span> <span class="n">offset</span><span class="p">,</span> <span class="n">width</span><span class="p">};</span>
    <span class="kt">int</span> <span class="n">type</span> <span class="o">=</span> <span class="n">request</span><span class="p">.</span><span class="n">send_back_parameter_type</span><span class="p">();</span>
    <span class="n">sendBackParameterSparse</span><span class="p">(</span><span class="n">block</span><span class="p">,</span> <span class="n">type</span><span class="p">,</span> <span class="n">response</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">buf</span><span class="p">,</span> <span class="n">width</span><span class="p">,</span> <span class="n">outputBuffers</span><span class="p">);</span>
    <span class="n">offset</span> <span class="o">+=</span> <span class="n">width</span><span class="p">;</span>
  <span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<p><code class="docutils literal"><span class="pre">getParameterConfig(block).dims(1)</span></code> returns the width of the current &#8220;parameter block&#8221;(a shard of parameter object),
then <code class="docutils literal"><span class="pre">getParameterSparse</span></code> remote call returns only one row of data to the client.</p>
</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="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></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>