executor.html



<!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>Executor Design Doc &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"/> 

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

</head>

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

  <div class="wy-grid-for-nav">

    
    <nav data-toggle="wy-nav-shift" class="wy-nav-side">
      <div class="wy-side-scroll">
        <div class="wy-side-nav-search">
          

            <a href="../index_en.html" class="icon icon-home"> PaddlePaddle
          

          </a>

          
<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 class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="main navigation">
          
            
                <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="../build_and_install/index_en.html">Install and Build</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="../dev/index_en.html">Development</a></li>
<li class="toctree-l1"><a class="reference internal" href="../faq/index_en.html">FAQ</a></li>
</ul>

            
        </div>
      </div>
    </nav>

    <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">

      
      <nav class="wy-nav-top" role="navigation" aria-label="top navigation">
        <i data-toggle="wy-nav-top" class="fa fa-bars"></i>
        <a href="../index_en.html">PaddlePaddle</a>
      </nav>


      <div class="wy-nav-content">
        <div class="rst-content">
          

<div role="navigation" aria-label="breadcrumbs navigation">
  <ul class="wy-breadcrumbs">
    <li><a href="../index_en.html">Docs</a> &raquo;</li>
      
    <li>Executor Design Doc</li>
      <li class="wy-breadcrumbs-aside">
        
          
            <a href="../_sources/design/executor.md.txt" rel="nofollow"> View page source</a>
          
        
      </li>
  </ul>
  <hr/>
</div>
          <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
           <div itemprop="articleBody">
            
  <div class="section" id="executor-design-doc">
<span id="executor-design-doc"></span><h1>Executor Design Doc<a class="headerlink" href="#executor-design-doc" title="Permalink to this headline">¶</a></h1>
<div class="section" id="motivation">
<span id="motivation"></span><h2>Motivation<a class="headerlink" href="#motivation" title="Permalink to this headline">¶</a></h2>
<p>In <a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/develop/doc/design/fluid.md">fluid</a>, we encourage the user to use deep learning programming paradigms to describe the training process. When the user-written Python program is executed, it will first create a protobuf message
<a class="reference external" href="https://github.com/PaddlePaddle/Paddle/blob/a91efdde6910ce92a78e3aa7157412c4c88d9ee8/paddle/framework/framework.proto#L145"><code class="docutils literal"><span class="pre">ProgramDesc</span></code></a> that describes the process and is conceptually like an <a class="reference external" href="https://en.wikipedia.org/wiki/Abstract_syntax_tree">abstract syntax tree</a>.</p>
<p>The executor runs the <code class="docutils literal"><span class="pre">ProgramDesc</span></code> like an interpreter. <code class="docutils literal"><span class="pre">ProgramDesc</span></code> contains the intrinsics (operators in this case) and variables which will be used, executor explicitly executes the stored precompiled code.</p>
</div>
<div class="section" id="overview">
<span id="overview"></span><h2>Overview<a class="headerlink" href="#overview" title="Permalink to this headline">¶</a></h2>
<p>An executor takes a <code class="docutils literal"><span class="pre">ProgramDesc</span></code>, a <code class="docutils literal"><span class="pre">block_id</span></code> and a <code class="docutils literal"><span class="pre">Scope</span></code>.  The <code class="docutils literal"><span class="pre">ProgramDesc</span></code> is a list of blocks and each block contains the protobuf definition of all the parameters and operators in the block. The <code class="docutils literal"><span class="pre">block_id</span></code> specifies the entrance block. And the <code class="docutils literal"><span class="pre">Scope</span></code> is the container of all the variable instances, which is persistent throughout different runs.</p>
</div>
<div class="section" id="executor">
<span id="executor"></span><h2>Executor<a class="headerlink" href="#executor" title="Permalink to this headline">¶</a></h2>
<p>The <code class="docutils literal"><span class="pre">Executor</span></code> explicitly executes all the intrinsics (operators here) in the <code class="docutils literal"><span class="pre">block_id</span></code>th block of a <code class="docutils literal"><span class="pre">ProgramDesc</span></code>. Essentially, it instantiates Variables and Operators, then runs all the operators in sequence one-by-one.
It is very similar to how a push stack frame works when entering a block, following which it cleans up all the temporary variables when a mini-batch is finished. It does not however, have the stack frame pop process.</p>
<div class="section" id="the-interface">
<span id="the-interface"></span><h3>The interface<a class="headerlink" href="#the-interface" title="Permalink to this headline">¶</a></h3>
<div class="highlight-c++"><div class="highlight"><pre><span></span>  <span class="n">Executor</span><span class="p">(</span><span class="n">places</span><span class="p">);</span>
</pre></div>
</div>
<p>A executor does not own any computing resources, a user can only construct an executor using the specified places.</p>
</div>
<div class="section" id="running-an-executor">
<span id="running-an-executor"></span><h3>Running an Executor<a class="headerlink" href="#running-an-executor" title="Permalink to this headline">¶</a></h3>
<div class="highlight-default"><div class="highlight"><pre><span></span>  <span class="n">void</span> <span class="n">Run</span><span class="p">(</span><span class="n">ProgramDesc</span><span class="p">,</span> <span class="n">Scope</span><span class="p">,</span> <span class="n">block_id</span><span class="p">,</span> <span class="n">create_local_scope</span><span class="p">);</span>
</pre></div>
</div>
<p>An <code class="docutils literal"><span class="pre">Executor</span></code> only provides a unified way to execute <code class="docutils literal"><span class="pre">ProgramDesc</span></code>. <code class="docutils literal"><span class="pre">ProgramDesc</span></code> is the target that will be executed, the <code class="docutils literal"><span class="pre">Scope</span></code> specifies the variable container, the <code class="docutils literal"><span class="pre">block_id</span></code> indicates the entrance block and <code class="docutils literal"><span class="pre">create_local_scope</span></code> is a boolean that states whether it will destroy the temporary variables after the execution is finished.</p>
</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
        };
    </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 type="text/javascript">
      jQuery(function () {
          SphinxRtdTheme.StickyNav.enable();
      });
  </script>
   

</body>
</html>