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| <h1 class="title">Quick Start</h1> |
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| |
| <ul id="markdown-toc"> |
| <li><a href="#interactive-analysis-with-the-spark-shell" id="markdown-toc-interactive-analysis-with-the-spark-shell">Interactive Analysis with the Spark Shell</a> <ul> |
| <li><a href="#basics" id="markdown-toc-basics">Basics</a></li> |
| <li><a href="#more-on-rdd-operations" id="markdown-toc-more-on-rdd-operations">More on RDD Operations</a></li> |
| <li><a href="#caching" id="markdown-toc-caching">Caching</a></li> |
| </ul> |
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| <li><a href="#self-contained-applications" id="markdown-toc-self-contained-applications">Self-Contained Applications</a></li> |
| <li><a href="#where-to-go-from-here" id="markdown-toc-where-to-go-from-here">Where to Go from Here</a></li> |
| </ul> |
| |
| <p>This tutorial provides a quick introduction to using Spark. We will first introduce the API through Spark’s |
| interactive shell (in Python or Scala), |
| then show how to write applications in Java, Scala, and Python. |
| See the <a href="programming-guide.html">programming guide</a> for a more complete reference.</p> |
| |
| <p>To follow along with this guide, first download a packaged release of Spark from the |
| <a href="http://spark.apache.org/downloads.html">Spark website</a>. Since we won’t be using HDFS, |
| you can download a package for any version of Hadoop.</p> |
| |
| <h1 id="interactive-analysis-with-the-spark-shell">Interactive Analysis with the Spark Shell</h1> |
| |
| <h2 id="basics">Basics</h2> |
| |
| <p>Spark’s shell provides a simple way to learn the API, as well as a powerful tool to analyze data interactively. |
| It is available in either Scala (which runs on the Java VM and is thus a good way to use existing Java libraries) |
| or Python. Start it by running the following in the Spark directory:</p> |
| |
| <div class="codetabs"> |
| <div data-lang="scala"> |
| |
| <pre><code>./bin/spark-shell |
| </code></pre> |
| |
| <p>Spark’s primary abstraction is a distributed collection of items called a Resilient Distributed Dataset (RDD). RDDs can be created from Hadoop InputFormats (such as HDFS files) or by transforming other RDDs. Let’s make a new RDD from the text of the README file in the Spark source directory:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="k">val</span> <span class="n">textFile</span> <span class="k">=</span> <span class="n">sc</span><span class="o">.</span><span class="n">textFile</span><span class="o">(</span><span class="s">"README.md"</span><span class="o">)</span> |
| <span class="n">textFile</span><span class="k">:</span> <span class="kt">spark.RDD</span><span class="o">[</span><span class="kt">String</span><span class="o">]</span> <span class="k">=</span> <span class="n">spark</span><span class="o">.</span><span class="nc">MappedRDD</span><span class="k">@</span><span class="mi">2</span><span class="n">ee9b6e3</span></code></pre></div> |
| |
| <p>RDDs have <em><a href="programming-guide.html#actions">actions</a></em>, which return values, and <em><a href="programming-guide.html#transformations">transformations</a></em>, which return pointers to new RDDs. Let’s start with a few actions:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="n">textFile</span><span class="o">.</span><span class="n">count</span><span class="o">()</span> <span class="c1">// Number of items in this RDD</span> |
| <span class="n">res0</span><span class="k">:</span> <span class="kt">Long</span> <span class="o">=</span> <span class="mi">126</span> |
| |
| <span class="n">scala</span><span class="o">></span> <span class="n">textFile</span><span class="o">.</span><span class="n">first</span><span class="o">()</span> <span class="c1">// First item in this RDD</span> |
| <span class="n">res1</span><span class="k">:</span> <span class="kt">String</span> <span class="o">=</span> <span class="k">#</span> <span class="nc">Apache</span> <span class="nc">Spark</span></code></pre></div> |
| |
| <p>Now let’s use a transformation. We will use the <a href="programming-guide.html#transformations"><code>filter</code></a> transformation to return a new RDD with a subset of the items in the file.</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="k">val</span> <span class="n">linesWithSpark</span> <span class="k">=</span> <span class="n">textFile</span><span class="o">.</span><span class="n">filter</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">contains</span><span class="o">(</span><span class="s">"Spark"</span><span class="o">))</span> |
| <span class="n">linesWithSpark</span><span class="k">:</span> <span class="kt">spark.RDD</span><span class="o">[</span><span class="kt">String</span><span class="o">]</span> <span class="k">=</span> <span class="n">spark</span><span class="o">.</span><span class="nc">FilteredRDD</span><span class="k">@</span><span class="mi">7</span><span class="n">dd4af09</span></code></pre></div> |
| |
| <p>We can chain together transformations and actions:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="n">textFile</span><span class="o">.</span><span class="n">filter</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">contains</span><span class="o">(</span><span class="s">"Spark"</span><span class="o">)).</span><span class="n">count</span><span class="o">()</span> <span class="c1">// How many lines contain "Spark"?</span> |
| <span class="n">res3</span><span class="k">:</span> <span class="kt">Long</span> <span class="o">=</span> <span class="mi">15</span></code></pre></div> |
| |
| </div> |
| <div data-lang="python"> |
| |
| <pre><code>./bin/pyspark |
| </code></pre> |
| |
| <p>Spark’s primary abstraction is a distributed collection of items called a Resilient Distributed Dataset (RDD). RDDs can be created from Hadoop InputFormats (such as HDFS files) or by transforming other RDDs. Let’s make a new RDD from the text of the README file in the Spark source directory:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">textFile</span> <span class="o">=</span> <span class="n">sc</span><span class="o">.</span><span class="n">textFile</span><span class="p">(</span><span class="s">"README.md"</span><span class="p">)</span></code></pre></div> |
| |
| <p>RDDs have <em><a href="programming-guide.html#actions">actions</a></em>, which return values, and <em><a href="programming-guide.html#transformations">transformations</a></em>, which return pointers to new RDDs. Let’s start with a few actions:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">textFile</span><span class="o">.</span><span class="n">count</span><span class="p">()</span> <span class="c"># Number of items in this RDD</span> |
| <span class="mi">126</span> |
| |
| <span class="o">>>></span> <span class="n">textFile</span><span class="o">.</span><span class="n">first</span><span class="p">()</span> <span class="c"># First item in this RDD</span> |
| <span class="s">u'# Apache Spark'</span></code></pre></div> |
| |
| <p>Now let’s use a transformation. We will use the <a href="programming-guide.html#transformations"><code>filter</code></a> transformation to return a new RDD with a subset of the items in the file.</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">linesWithSpark</span> <span class="o">=</span> <span class="n">textFile</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="k">lambda</span> <span class="n">line</span><span class="p">:</span> <span class="s">"Spark"</span> <span class="ow">in</span> <span class="n">line</span><span class="p">)</span></code></pre></div> |
| |
| <p>We can chain together transformations and actions:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">textFile</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="k">lambda</span> <span class="n">line</span><span class="p">:</span> <span class="s">"Spark"</span> <span class="ow">in</span> <span class="n">line</span><span class="p">)</span><span class="o">.</span><span class="n">count</span><span class="p">()</span> <span class="c"># How many lines contain "Spark"?</span> |
| <span class="mi">15</span></code></pre></div> |
| |
| </div> |
| </div> |
| |
| <h2 id="more-on-rdd-operations">More on RDD Operations</h2> |
| <p>RDD actions and transformations can be used for more complex computations. Let’s say we want to find the line with the most words:</p> |
| |
| <div class="codetabs"> |
| <div data-lang="scala"> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="n">textFile</span><span class="o">.</span><span class="n">map</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">split</span><span class="o">(</span><span class="s">" "</span><span class="o">).</span><span class="n">size</span><span class="o">).</span><span class="n">reduce</span><span class="o">((</span><span class="n">a</span><span class="o">,</span> <span class="n">b</span><span class="o">)</span> <span class="k">=></span> <span class="k">if</span> <span class="o">(</span><span class="n">a</span> <span class="o">></span> <span class="n">b</span><span class="o">)</span> <span class="n">a</span> <span class="k">else</span> <span class="n">b</span><span class="o">)</span> |
| <span class="n">res4</span><span class="k">:</span> <span class="kt">Long</span> <span class="o">=</span> <span class="mi">15</span></code></pre></div> |
| |
| <p>This first maps a line to an integer value, creating a new RDD. <code>reduce</code> is called on that RDD to find the largest line count. The arguments to <code>map</code> and <code>reduce</code> are Scala function literals (closures), and can use any language feature or Scala/Java library. For example, we can easily call functions declared elsewhere. We’ll use <code>Math.max()</code> function to make this code easier to understand:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="k">import</span> <span class="nn">java.lang.Math</span> |
| <span class="k">import</span> <span class="nn">java.lang.Math</span> |
| |
| <span class="n">scala</span><span class="o">></span> <span class="n">textFile</span><span class="o">.</span><span class="n">map</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">split</span><span class="o">(</span><span class="s">" "</span><span class="o">).</span><span class="n">size</span><span class="o">).</span><span class="n">reduce</span><span class="o">((</span><span class="n">a</span><span class="o">,</span> <span class="n">b</span><span class="o">)</span> <span class="k">=></span> <span class="nc">Math</span><span class="o">.</span><span class="n">max</span><span class="o">(</span><span class="n">a</span><span class="o">,</span> <span class="n">b</span><span class="o">))</span> |
| <span class="n">res5</span><span class="k">:</span> <span class="kt">Int</span> <span class="o">=</span> <span class="mi">15</span></code></pre></div> |
| |
| <p>One common data flow pattern is MapReduce, as popularized by Hadoop. Spark can implement MapReduce flows easily:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="k">val</span> <span class="n">wordCounts</span> <span class="k">=</span> <span class="n">textFile</span><span class="o">.</span><span class="n">flatMap</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">split</span><span class="o">(</span><span class="s">" "</span><span class="o">)).</span><span class="n">map</span><span class="o">(</span><span class="n">word</span> <span class="k">=></span> <span class="o">(</span><span class="n">word</span><span class="o">,</span> <span class="mi">1</span><span class="o">)).</span><span class="n">reduceByKey</span><span class="o">((</span><span class="n">a</span><span class="o">,</span> <span class="n">b</span><span class="o">)</span> <span class="k">=></span> <span class="n">a</span> <span class="o">+</span> <span class="n">b</span><span class="o">)</span> |
| <span class="n">wordCounts</span><span class="k">:</span> <span class="kt">spark.RDD</span><span class="o">[(</span><span class="kt">String</span>, <span class="kt">Int</span><span class="o">)]</span> <span class="k">=</span> <span class="n">spark</span><span class="o">.</span><span class="nc">ShuffledAggregatedRDD</span><span class="k">@</span><span class="mi">71</span><span class="n">f027b8</span></code></pre></div> |
| |
| <p>Here, we combined the <a href="programming-guide.html#transformations"><code>flatMap</code></a>, <a href="programming-guide.html#transformations"><code>map</code></a>, and <a href="programming-guide.html#transformations"><code>reduceByKey</code></a> transformations to compute the per-word counts in the file as an RDD of (String, Int) pairs. To collect the word counts in our shell, we can use the <a href="programming-guide.html#actions"><code>collect</code></a> action:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="n">wordCounts</span><span class="o">.</span><span class="n">collect</span><span class="o">()</span> |
| <span class="n">res6</span><span class="k">:</span> <span class="kt">Array</span><span class="o">[(</span><span class="kt">String</span>, <span class="kt">Int</span><span class="o">)]</span> <span class="k">=</span> <span class="nc">Array</span><span class="o">((</span><span class="n">means</span><span class="o">,</span><span class="mi">1</span><span class="o">),</span> <span class="o">(</span><span class="n">under</span><span class="o">,</span><span class="mi">2</span><span class="o">),</span> <span class="o">(</span><span class="k">this</span><span class="o">,</span><span class="mi">3</span><span class="o">),</span> <span class="o">(</span><span class="nc">Because</span><span class="o">,</span><span class="mi">1</span><span class="o">),</span> <span class="o">(</span><span class="nc">Python</span><span class="o">,</span><span class="mi">2</span><span class="o">),</span> <span class="o">(</span><span class="n">agree</span><span class="o">,</span><span class="mi">1</span><span class="o">),</span> <span class="o">(</span><span class="n">cluster</span><span class="o">.,</span><span class="mi">1</span><span class="o">),</span> <span class="o">...)</span></code></pre></div> |
| |
| </div> |
| <div data-lang="python"> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">textFile</span><span class="o">.</span><span class="n">map</span><span class="p">(</span><span class="k">lambda</span> <span class="n">line</span><span class="p">:</span> <span class="nb">len</span><span class="p">(</span><span class="n">line</span><span class="o">.</span><span class="n">split</span><span class="p">()))</span><span class="o">.</span><span class="n">reduce</span><span class="p">(</span><span class="k">lambda</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">:</span> <span class="n">a</span> <span class="k">if</span> <span class="p">(</span><span class="n">a</span> <span class="o">></span> <span class="n">b</span><span class="p">)</span> <span class="k">else</span> <span class="n">b</span><span class="p">)</span> |
| <span class="mi">15</span></code></pre></div> |
| |
| <p>This first maps a line to an integer value, creating a new RDD. <code>reduce</code> is called on that RDD to find the largest line count. The arguments to <code>map</code> and <code>reduce</code> are Python <a href="https://docs.python.org/2/reference/expressions.html#lambda">anonymous functions (lambdas)</a>, |
| but we can also pass any top-level Python function we want. |
| For example, we’ll define a <code>max</code> function to make this code easier to understand:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="k">def</span> <span class="nf">max</span><span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">):</span> |
| <span class="o">...</span> <span class="k">if</span> <span class="n">a</span> <span class="o">></span> <span class="n">b</span><span class="p">:</span> |
| <span class="o">...</span> <span class="k">return</span> <span class="n">a</span> |
| <span class="o">...</span> <span class="k">else</span><span class="p">:</span> |
| <span class="o">...</span> <span class="k">return</span> <span class="n">b</span> |
| <span class="o">...</span> |
| |
| <span class="o">>>></span> <span class="n">textFile</span><span class="o">.</span><span class="n">map</span><span class="p">(</span><span class="k">lambda</span> <span class="n">line</span><span class="p">:</span> <span class="nb">len</span><span class="p">(</span><span class="n">line</span><span class="o">.</span><span class="n">split</span><span class="p">()))</span><span class="o">.</span><span class="n">reduce</span><span class="p">(</span><span class="nb">max</span><span class="p">)</span> |
| <span class="mi">15</span></code></pre></div> |
| |
| <p>One common data flow pattern is MapReduce, as popularized by Hadoop. Spark can implement MapReduce flows easily:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">wordCounts</span> <span class="o">=</span> <span class="n">textFile</span><span class="o">.</span><span class="n">flatMap</span><span class="p">(</span><span class="k">lambda</span> <span class="n">line</span><span class="p">:</span> <span class="n">line</span><span class="o">.</span><span class="n">split</span><span class="p">())</span><span class="o">.</span><span class="n">map</span><span class="p">(</span><span class="k">lambda</span> <span class="n">word</span><span class="p">:</span> <span class="p">(</span><span class="n">word</span><span class="p">,</span> <span class="mi">1</span><span class="p">))</span><span class="o">.</span><span class="n">reduceByKey</span><span class="p">(</span><span class="k">lambda</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span><span class="p">:</span> <span class="n">a</span><span class="o">+</span><span class="n">b</span><span class="p">)</span></code></pre></div> |
| |
| <p>Here, we combined the <a href="programming-guide.html#transformations"><code>flatMap</code></a>, <a href="programming-guide.html#transformations"><code>map</code></a>, and <a href="programming-guide.html#transformations"><code>reduceByKey</code></a> transformations to compute the per-word counts in the file as an RDD of (string, int) pairs. To collect the word counts in our shell, we can use the <a href="programming-guide.html#actions"><code>collect</code></a> action:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">wordCounts</span><span class="o">.</span><span class="n">collect</span><span class="p">()</span> |
| <span class="p">[(</span><span class="s">u'and'</span><span class="p">,</span> <span class="mi">9</span><span class="p">),</span> <span class="p">(</span><span class="s">u'A'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="p">(</span><span class="s">u'webpage'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="p">(</span><span class="s">u'README'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="p">(</span><span class="s">u'Note'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="p">(</span><span class="s">u'"local"'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="p">(</span><span class="s">u'variable'</span><span class="p">,</span> <span class="mi">1</span><span class="p">),</span> <span class="o">...</span><span class="p">]</span></code></pre></div> |
| |
| </div> |
| </div> |
| |
| <h2 id="caching">Caching</h2> |
| <p>Spark also supports pulling data sets into a cluster-wide in-memory cache. This is very useful when data is accessed repeatedly, such as when querying a small “hot” dataset or when running an iterative algorithm like PageRank. As a simple example, let’s mark our <code>linesWithSpark</code> dataset to be cached:</p> |
| |
| <div class="codetabs"> |
| <div data-lang="scala"> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">scala</span><span class="o">></span> <span class="n">linesWithSpark</span><span class="o">.</span><span class="n">cache</span><span class="o">()</span> |
| <span class="n">res7</span><span class="k">:</span> <span class="kt">spark.RDD</span><span class="o">[</span><span class="kt">String</span><span class="o">]</span> <span class="k">=</span> <span class="n">spark</span><span class="o">.</span><span class="nc">FilteredRDD</span><span class="k">@</span><span class="mi">17</span><span class="n">e51082</span> |
| |
| <span class="n">scala</span><span class="o">></span> <span class="n">linesWithSpark</span><span class="o">.</span><span class="n">count</span><span class="o">()</span> |
| <span class="n">res8</span><span class="k">:</span> <span class="kt">Long</span> <span class="o">=</span> <span class="mi">19</span> |
| |
| <span class="n">scala</span><span class="o">></span> <span class="n">linesWithSpark</span><span class="o">.</span><span class="n">count</span><span class="o">()</span> |
| <span class="n">res9</span><span class="k">:</span> <span class="kt">Long</span> <span class="o">=</span> <span class="mi">19</span></code></pre></div> |
| |
| <p>It may seem silly to use Spark to explore and cache a 100-line text file. The interesting part is |
| that these same functions can be used on very large data sets, even when they are striped across |
| tens or hundreds of nodes. You can also do this interactively by connecting <code>bin/spark-shell</code> to |
| a cluster, as described in the <a href="programming-guide.html#initializing-spark">programming guide</a>.</p> |
| |
| </div> |
| <div data-lang="python"> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="o">>>></span> <span class="n">linesWithSpark</span><span class="o">.</span><span class="n">cache</span><span class="p">()</span> |
| |
| <span class="o">>>></span> <span class="n">linesWithSpark</span><span class="o">.</span><span class="n">count</span><span class="p">()</span> |
| <span class="mi">19</span> |
| |
| <span class="o">>>></span> <span class="n">linesWithSpark</span><span class="o">.</span><span class="n">count</span><span class="p">()</span> |
| <span class="mi">19</span></code></pre></div> |
| |
| <p>It may seem silly to use Spark to explore and cache a 100-line text file. The interesting part is |
| that these same functions can be used on very large data sets, even when they are striped across |
| tens or hundreds of nodes. You can also do this interactively by connecting <code>bin/pyspark</code> to |
| a cluster, as described in the <a href="programming-guide.html#initializing-spark">programming guide</a>.</p> |
| |
| </div> |
| </div> |
| |
| <h1 id="self-contained-applications">Self-Contained Applications</h1> |
| <p>Suppose we wish to write a self-contained application using the Spark API. We will walk through a |
| simple application in Scala (with sbt), Java (with Maven), and Python.</p> |
| |
| <div class="codetabs"> |
| <div data-lang="scala"> |
| |
| <p>We’ll create a very simple Spark application in Scala–so simple, in fact, that it’s |
| named <code>SimpleApp.scala</code>:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="cm">/* SimpleApp.scala */</span> |
| <span class="k">import</span> <span class="nn">org.apache.spark.SparkContext</span> |
| <span class="k">import</span> <span class="nn">org.apache.spark.SparkContext._</span> |
| <span class="k">import</span> <span class="nn">org.apache.spark.SparkConf</span> |
| |
| <span class="k">object</span> <span class="nc">SimpleApp</span> <span class="o">{</span> |
| <span class="k">def</span> <span class="n">main</span><span class="o">(</span><span class="n">args</span><span class="k">:</span> <span class="kt">Array</span><span class="o">[</span><span class="kt">String</span><span class="o">])</span> <span class="o">{</span> |
| <span class="k">val</span> <span class="n">logFile</span> <span class="k">=</span> <span class="s">"YOUR_SPARK_HOME/README.md"</span> <span class="c1">// Should be some file on your system</span> |
| <span class="k">val</span> <span class="n">conf</span> <span class="k">=</span> <span class="k">new</span> <span class="nc">SparkConf</span><span class="o">().</span><span class="n">setAppName</span><span class="o">(</span><span class="s">"Simple Application"</span><span class="o">)</span> |
| <span class="k">val</span> <span class="n">sc</span> <span class="k">=</span> <span class="k">new</span> <span class="nc">SparkContext</span><span class="o">(</span><span class="n">conf</span><span class="o">)</span> |
| <span class="k">val</span> <span class="n">logData</span> <span class="k">=</span> <span class="n">sc</span><span class="o">.</span><span class="n">textFile</span><span class="o">(</span><span class="n">logFile</span><span class="o">,</span> <span class="mi">2</span><span class="o">).</span><span class="n">cache</span><span class="o">()</span> |
| <span class="k">val</span> <span class="n">numAs</span> <span class="k">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">contains</span><span class="o">(</span><span class="s">"a"</span><span class="o">)).</span><span class="n">count</span><span class="o">()</span> |
| <span class="k">val</span> <span class="n">numBs</span> <span class="k">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="o">(</span><span class="n">line</span> <span class="k">=></span> <span class="n">line</span><span class="o">.</span><span class="n">contains</span><span class="o">(</span><span class="s">"b"</span><span class="o">)).</span><span class="n">count</span><span class="o">()</span> |
| <span class="n">println</span><span class="o">(</span><span class="s">"Lines with a: %s, Lines with b: %s"</span><span class="o">.</span><span class="n">format</span><span class="o">(</span><span class="n">numAs</span><span class="o">,</span> <span class="n">numBs</span><span class="o">))</span> |
| <span class="o">}</span> |
| <span class="o">}</span></code></pre></div> |
| |
| <p>Note that applications should define a <code>main()</code> method instead of extending <code>scala.App</code>. |
| Subclasses of <code>scala.App</code> may not work correctly.</p> |
| |
| <p>This program just counts the number of lines containing ‘a’ and the number containing ‘b’ in the |
| Spark README. Note that you’ll need to replace YOUR_SPARK_HOME with the location where Spark is |
| installed. Unlike the earlier examples with the Spark shell, which initializes its own SparkContext, |
| we initialize a SparkContext as part of the program.</p> |
| |
| <p>We pass the SparkContext constructor a |
| <a href="api/scala/index.html#org.apache.spark.SparkConf">SparkConf</a> |
| object which contains information about our |
| application.</p> |
| |
| <p>Our application depends on the Spark API, so we’ll also include an sbt configuration file, |
| <code>simple.sbt</code>, which explains that Spark is a dependency. This file also adds a repository that |
| Spark depends on:</p> |
| |
| <div class="highlight"><pre><code class="language-scala" data-lang="scala"><span class="n">name</span> <span class="o">:=</span> <span class="s">"Simple Project"</span> |
| |
| <span class="n">version</span> <span class="o">:=</span> <span class="s">"1.0"</span> |
| |
| <span class="n">scalaVersion</span> <span class="o">:=</span> <span class="s">"2.10.5"</span> |
| |
| <span class="n">libraryDependencies</span> <span class="o">+=</span> <span class="s">"org.apache.spark"</span> <span class="o">%%</span> <span class="s">"spark-core"</span> <span class="o">%</span> <span class="s">"1.6.2"</span></code></pre></div> |
| |
| <p>For sbt to work correctly, we’ll need to layout <code>SimpleApp.scala</code> and <code>simple.sbt</code> |
| according to the typical directory structure. Once that is in place, we can create a JAR package |
| containing the application’s code, then use the <code>spark-submit</code> script to run our program.</p> |
| |
| <div class="highlight"><pre><code class="language-bash" data-lang="bash"><span class="c"># Your directory layout should look like this</span> |
| <span class="nv">$ </span>find . |
| . |
| ./simple.sbt |
| ./src |
| ./src/main |
| ./src/main/scala |
| ./src/main/scala/SimpleApp.scala |
| |
| <span class="c"># Package a jar containing your application</span> |
| <span class="nv">$ </span>sbt package |
| ... |
| <span class="o">[</span>info<span class="o">]</span> Packaging <span class="o">{</span>..<span class="o">}</span>/<span class="o">{</span>..<span class="o">}</span>/target/scala-2.10/simple-project_2.10-1.0.jar |
| |
| <span class="c"># Use spark-submit to run your application</span> |
| <span class="nv">$ </span>YOUR_SPARK_HOME/bin/spark-submit <span class="se">\</span> |
| --class <span class="s2">"SimpleApp"</span> <span class="se">\</span> |
| --master <span class="nb">local</span><span class="o">[</span>4<span class="o">]</span> <span class="se">\</span> |
| target/scala-2.10/simple-project_2.10-1.0.jar |
| ... |
| Lines with a: 46, Lines with b: 23</code></pre></div> |
| |
| </div> |
| <div data-lang="java"> |
| <p>This example will use Maven to compile an application JAR, but any similar build system will work.</p> |
| |
| <p>We’ll create a very simple Spark application, <code>SimpleApp.java</code>:</p> |
| |
| <div class="highlight"><pre><code class="language-java" data-lang="java"><span class="cm">/* SimpleApp.java */</span> |
| <span class="kn">import</span> <span class="nn">org.apache.spark.api.java.*</span><span class="o">;</span> |
| <span class="kn">import</span> <span class="nn">org.apache.spark.SparkConf</span><span class="o">;</span> |
| <span class="kn">import</span> <span class="nn">org.apache.spark.api.java.function.Function</span><span class="o">;</span> |
| |
| <span class="kd">public</span> <span class="kd">class</span> <span class="nc">SimpleApp</span> <span class="o">{</span> |
| <span class="kd">public</span> <span class="kd">static</span> <span class="kt">void</span> <span class="nf">main</span><span class="o">(</span><span class="n">String</span><span class="o">[]</span> <span class="n">args</span><span class="o">)</span> <span class="o">{</span> |
| <span class="n">String</span> <span class="n">logFile</span> <span class="o">=</span> <span class="s">"YOUR_SPARK_HOME/README.md"</span><span class="o">;</span> <span class="c1">// Should be some file on your system</span> |
| <span class="n">SparkConf</span> <span class="n">conf</span> <span class="o">=</span> <span class="k">new</span> <span class="nf">SparkConf</span><span class="o">().</span><span class="na">setAppName</span><span class="o">(</span><span class="s">"Simple Application"</span><span class="o">);</span> |
| <span class="n">JavaSparkContext</span> <span class="n">sc</span> <span class="o">=</span> <span class="k">new</span> <span class="nf">JavaSparkContext</span><span class="o">(</span><span class="n">conf</span><span class="o">);</span> |
| <span class="n">JavaRDD</span><span class="o"><</span><span class="n">String</span><span class="o">></span> <span class="n">logData</span> <span class="o">=</span> <span class="n">sc</span><span class="o">.</span><span class="na">textFile</span><span class="o">(</span><span class="n">logFile</span><span class="o">).</span><span class="na">cache</span><span class="o">();</span> |
| |
| <span class="kt">long</span> <span class="n">numAs</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="na">filter</span><span class="o">(</span><span class="k">new</span> <span class="n">Function</span><span class="o"><</span><span class="n">String</span><span class="o">,</span> <span class="n">Boolean</span><span class="o">>()</span> <span class="o">{</span> |
| <span class="kd">public</span> <span class="n">Boolean</span> <span class="nf">call</span><span class="o">(</span><span class="n">String</span> <span class="n">s</span><span class="o">)</span> <span class="o">{</span> <span class="k">return</span> <span class="n">s</span><span class="o">.</span><span class="na">contains</span><span class="o">(</span><span class="s">"a"</span><span class="o">);</span> <span class="o">}</span> |
| <span class="o">}).</span><span class="na">count</span><span class="o">();</span> |
| |
| <span class="kt">long</span> <span class="n">numBs</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="na">filter</span><span class="o">(</span><span class="k">new</span> <span class="n">Function</span><span class="o"><</span><span class="n">String</span><span class="o">,</span> <span class="n">Boolean</span><span class="o">>()</span> <span class="o">{</span> |
| <span class="kd">public</span> <span class="n">Boolean</span> <span class="nf">call</span><span class="o">(</span><span class="n">String</span> <span class="n">s</span><span class="o">)</span> <span class="o">{</span> <span class="k">return</span> <span class="n">s</span><span class="o">.</span><span class="na">contains</span><span class="o">(</span><span class="s">"b"</span><span class="o">);</span> <span class="o">}</span> |
| <span class="o">}).</span><span class="na">count</span><span class="o">();</span> |
| |
| <span class="n">System</span><span class="o">.</span><span class="na">out</span><span class="o">.</span><span class="na">println</span><span class="o">(</span><span class="s">"Lines with a: "</span> <span class="o">+</span> <span class="n">numAs</span> <span class="o">+</span> <span class="s">", lines with b: "</span> <span class="o">+</span> <span class="n">numBs</span><span class="o">);</span> |
| <span class="o">}</span> |
| <span class="o">}</span></code></pre></div> |
| |
| <p>This program just counts the number of lines containing ‘a’ and the number containing ‘b’ in a text |
| file. Note that you’ll need to replace YOUR_SPARK_HOME with the location where Spark is installed. |
| As with the Scala example, we initialize a SparkContext, though we use the special |
| <code>JavaSparkContext</code> class to get a Java-friendly one. We also create RDDs (represented by |
| <code>JavaRDD</code>) and run transformations on them. Finally, we pass functions to Spark by creating classes |
| that extend <code>spark.api.java.function.Function</code>. The |
| <a href="programming-guide.html">Spark programming guide</a> describes these differences in more detail.</p> |
| |
| <p>To build the program, we also write a Maven <code>pom.xml</code> file that lists Spark as a dependency. |
| Note that Spark artifacts are tagged with a Scala version.</p> |
| |
| <div class="highlight"><pre><code class="language-xml" data-lang="xml"><span class="nt"><project></span> |
| <span class="nt"><groupId></span>edu.berkeley<span class="nt"></groupId></span> |
| <span class="nt"><artifactId></span>simple-project<span class="nt"></artifactId></span> |
| <span class="nt"><modelVersion></span>4.0.0<span class="nt"></modelVersion></span> |
| <span class="nt"><name></span>Simple Project<span class="nt"></name></span> |
| <span class="nt"><packaging></span>jar<span class="nt"></packaging></span> |
| <span class="nt"><version></span>1.0<span class="nt"></version></span> |
| <span class="nt"><dependencies></span> |
| <span class="nt"><dependency></span> <span class="c"><!-- Spark dependency --></span> |
| <span class="nt"><groupId></span>org.apache.spark<span class="nt"></groupId></span> |
| <span class="nt"><artifactId></span>spark-core_2.10<span class="nt"></artifactId></span> |
| <span class="nt"><version></span>1.6.2<span class="nt"></version></span> |
| <span class="nt"></dependency></span> |
| <span class="nt"></dependencies></span> |
| <span class="nt"></project></span></code></pre></div> |
| |
| <p>We lay out these files according to the canonical Maven directory structure:</p> |
| |
| <div class="highlight"><pre><code class="language-bash" data-lang="bash"><span class="nv">$ </span>find . |
| ./pom.xml |
| ./src |
| ./src/main |
| ./src/main/java |
| ./src/main/java/SimpleApp.java</code></pre></div> |
| |
| <p>Now, we can package the application using Maven and execute it with <code>./bin/spark-submit</code>.</p> |
| |
| <div class="highlight"><pre><code class="language-bash" data-lang="bash"><span class="c"># Package a JAR containing your application</span> |
| <span class="nv">$ </span>mvn package |
| ... |
| <span class="o">[</span>INFO<span class="o">]</span> Building jar: <span class="o">{</span>..<span class="o">}</span>/<span class="o">{</span>..<span class="o">}</span>/target/simple-project-1.0.jar |
| |
| <span class="c"># Use spark-submit to run your application</span> |
| <span class="nv">$ </span>YOUR_SPARK_HOME/bin/spark-submit <span class="se">\</span> |
| --class <span class="s2">"SimpleApp"</span> <span class="se">\</span> |
| --master <span class="nb">local</span><span class="o">[</span>4<span class="o">]</span> <span class="se">\</span> |
| target/simple-project-1.0.jar |
| ... |
| Lines with a: 46, Lines with b: 23</code></pre></div> |
| |
| </div> |
| <div data-lang="python"> |
| |
| <p>Now we will show how to write an application using the Python API (PySpark).</p> |
| |
| <p>As an example, we’ll create a simple Spark application, <code>SimpleApp.py</code>:</p> |
| |
| <div class="highlight"><pre><code class="language-python" data-lang="python"><span class="sd">"""SimpleApp.py"""</span> |
| <span class="kn">from</span> <span class="nn">pyspark</span> <span class="kn">import</span> <span class="n">SparkContext</span> |
| |
| <span class="n">logFile</span> <span class="o">=</span> <span class="s">"YOUR_SPARK_HOME/README.md"</span> <span class="c"># Should be some file on your system</span> |
| <span class="n">sc</span> <span class="o">=</span> <span class="n">SparkContext</span><span class="p">(</span><span class="s">"local"</span><span class="p">,</span> <span class="s">"Simple App"</span><span class="p">)</span> |
| <span class="n">logData</span> <span class="o">=</span> <span class="n">sc</span><span class="o">.</span><span class="n">textFile</span><span class="p">(</span><span class="n">logFile</span><span class="p">)</span><span class="o">.</span><span class="n">cache</span><span class="p">()</span> |
| |
| <span class="n">numAs</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="k">lambda</span> <span class="n">s</span><span class="p">:</span> <span class="s">'a'</span> <span class="ow">in</span> <span class="n">s</span><span class="p">)</span><span class="o">.</span><span class="n">count</span><span class="p">()</span> |
| <span class="n">numBs</span> <span class="o">=</span> <span class="n">logData</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="k">lambda</span> <span class="n">s</span><span class="p">:</span> <span class="s">'b'</span> <span class="ow">in</span> <span class="n">s</span><span class="p">)</span><span class="o">.</span><span class="n">count</span><span class="p">()</span> |
| |
| <span class="k">print</span><span class="p">(</span><span class="s">"Lines with a: </span><span class="si">%i</span><span class="s">, lines with b: </span><span class="si">%i</span><span class="s">"</span> <span class="o">%</span> <span class="p">(</span><span class="n">numAs</span><span class="p">,</span> <span class="n">numBs</span><span class="p">))</span></code></pre></div> |
| |
| <p>This program just counts the number of lines containing ‘a’ and the number containing ‘b’ in a |
| text file. |
| Note that you’ll need to replace YOUR_SPARK_HOME with the location where Spark is installed. |
| As with the Scala and Java examples, we use a SparkContext to create RDDs. |
| We can pass Python functions to Spark, which are automatically serialized along with any variables |
| that they reference. |
| For applications that use custom classes or third-party libraries, we can also add code |
| dependencies to <code>spark-submit</code> through its <code>--py-files</code> argument by packaging them into a |
| .zip file (see <code>spark-submit --help</code> for details). |
| <code>SimpleApp</code> is simple enough that we do not need to specify any code dependencies.</p> |
| |
| <p>We can run this application using the <code>bin/spark-submit</code> script:</p> |
| |
| <div class="highlight"><pre><code class="language-bash" data-lang="bash"><span class="c"># Use spark-submit to run your application</span> |
| <span class="nv">$ </span>YOUR_SPARK_HOME/bin/spark-submit <span class="se">\</span> |
| --master <span class="nb">local</span><span class="o">[</span>4<span class="o">]</span> <span class="se">\</span> |
| SimpleApp.py |
| ... |
| Lines with a: 46, Lines with b: 23</code></pre></div> |
| |
| </div> |
| </div> |
| |
| <h1 id="where-to-go-from-here">Where to Go from Here</h1> |
| <p>Congratulations on running your first Spark application!</p> |
| |
| <ul> |
| <li>For an in-depth overview of the API, start with the <a href="programming-guide.html">Spark programming guide</a>, |
| or see “Programming Guides” menu for other components.</li> |
| <li>For running applications on a cluster, head to the <a href="cluster-overview.html">deployment overview</a>.</li> |
| <li>Finally, Spark includes several samples in the <code>examples</code> directory |
| (<a href="https://github.com/apache/spark/tree/master/examples/src/main/scala/org/apache/spark/examples">Scala</a>, |
| <a href="https://github.com/apache/spark/tree/master/examples/src/main/java/org/apache/spark/examples">Java</a>, |
| <a href="https://github.com/apache/spark/tree/master/examples/src/main/python">Python</a>, |
| <a href="https://github.com/apache/spark/tree/master/examples/src/main/r">R</a>). |
| You can run them as follows:</li> |
| </ul> |
| |
| <div class="highlight"><pre><code class="language-bash" data-lang="bash"><span class="c"># For Scala and Java, use run-example:</span> |
| ./bin/run-example SparkPi |
| |
| <span class="c"># For Python examples, use spark-submit directly:</span> |
| ./bin/spark-submit examples/src/main/python/pi.py |
| |
| <span class="c"># For R examples, use spark-submit directly:</span> |
| ./bin/spark-submit examples/src/main/r/dataframe.R</code></pre></div> |
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