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spark-core.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>Apache Spark™ Workshop | Spark Core | The Core of Apache Spark</title>
<meta name="description" content="Apache Spark™ Workshop | Spark Core | The Core of Apache Spark">
<meta name="author" content="Jacek Laskowski">
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<div class="footer">
<footer style="font-size: small;">
© <a href="https://medium.com/@jaceklaskowski">Jacek Laskowski</a> 2019 / <a href="https://twitter.com/jaceklaskowski">@JacekLaskowski</a>
/ jacek@japila.pl
</footer>
</div>
<div class="slides">
<section class="intro" data-transition="zoom" id="home">
<p>
<img width="12%" style="background:none; border:none; box-shadow:none;" data-src="images/spark-logo.png">
<img width="6%" src="images/jacek_laskowski_20141201_512px.png" style="border: 0">
</p>
<h1 style="font-size: 3.17em;">The Core of Apache Spark</h1>
<h3>Apache Spark 2.4.1 / Spark Core</h3>
<h4 style="font-size: smaller;">
<a href="https://twitter.com/jaceklaskowski">@jaceklaskowski</a> / <a href="https://stackoverflow.com/users/1305344/jacek-laskowski">StackOverflow</a> / <a href="https://github.com/jaceklaskowski">GitHub</a>
<br>
The "Internals" Books: <a href="https://bit.ly/apache-spark-internals">Apache Spark</a> / <a href="https://bit.ly/spark-sql-internals">Spark SQL</a> / <a href="https://bit.ly/spark-structured-streaming">Spark Structured Streaming</a>
</h4>
</section>
<section id="agenda" data-markdown>
<textarea data-template>
## Agenda
1. [SparkConf](#/sparkconf)
1. [SparkContext](#/sparkcontext)
1. [RDD](#/rdd)
1. [RDD Operators](#/rdd-api)
1. [Shuffle](#/shuffle)
1. [DAGScheduler](#/dagscheduler)
1. [Tasks](#/tasks)
</textarea>
</section>
<section id="sparkconf" data-markdown>
<textarea data-template>
## SparkConf
1. **SparkConf** represents the configuration of your Spark application
1. Switch to [The Internals of Apache Spark](https://bit.ly/apache-spark-internals)
* [SparkConf — Spark Application's Configuration](https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-SparkConf.html)
</textarea>
</section>
<section id="sparkcontext">
<h2>SparkContext — The Entry Point to Spark Services</h2>
<ol>
<li><b>SparkContext</b> is the entry point to the Spark services in your Spark application</li>
<li>SparkContext manages the connection to a Spark execution environment
<ul>
<li>Defined using the <b>master URL</b></li>
</ul>
</li>
<li>Switch to Mastering Apache Spark 2
<ul>
<li><a href="https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-sparkcontext.html">SparkContext — Entry Point to Spark (Core)</a></li>
</ul>
</li>
</ol>
</section>
<section>
<section id="rdd" data-markdown>
<textarea data-template>
## RDD <small>(1 of 2)</small>
1. **RDD** - <b>R</b>esilient <b>D</b>istributed <b>D</b>ataset</li>
1. Main data abstraction
1. **Execution DAG**
* Metadata of a distributed computation
1. Custom RDDs per transformation
1. Switch to [The Internals of Apache Spark](https://bit.ly/apache-spark-internals)
* [RDD — Resilient Distributed Dataset](https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-rdd.html)
</textarea>
</section>
<section id="rdd-2" data-markdown>
<textarea data-template>
## RDD <small>(2 of 2)</small>
1. **RDD** is an abstract class with the following properties:
1. **Dependencies** — parent RDDs if any
1. **Partitions**
1. **compute** function: Partition => Iterator[T]
1. Optional **Partitioner** to define key hashing (hash, range)
1. Optional **preferred locations** for locality info
1. Switch to [RDD API scaladoc](http://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.rdd.RDD)
</textarea>
</section>
<section id="partitions">
<h2>Partitions</h2>
<ol>
<li>
<b>Partitions</b> are logical buckets for data.
</li>
<li>
Partitions correspond to Hadoop's splits (if the data lives on HDFS) or partitioning schemes in the source storage
</li>
<li>
RDD (and hence the data inside) is partitioned.
</li>
<li>
Spark manages data using partitions that helps parallelize distributed data processing with minimal network traffic for sending data between executors.
</li>
<li>
Data in partitions can be <b>skewed</b>, i.e. unevenly distributed across partitions.
</li>
</ol>
</section>
<section>
<p>
<img width="100%" src="images/spark-rdd-partitioned-distributed.png" style="border: 0">
</p>
</section>
</section>
<section id="rdd-api">
<h2>RDD Operators</h2>
<ol>
<li><b>Transformation</b> is a lazy RDD operation that creates one or many RDDs</li>
<li><b>Action</b> is a RDD operation that produces non-RDD Scala values</li>
<li>Switch to Mastering Apache Spark 2
<ul>
<li><a href="https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-rdd-operations.html">Operators - Transformations and Actions</a></li>
<li><a href="https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-rdd-transformations.html">Transformations</a></li>
<li><a href="https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-rdd-actions.html">Actions</a></li>
</ul>
</li>
</ol>
</section>
<section id="shuffle">
<h2>Shuffle</h2>
<ol>
<li>
<b>Shuffle</b> is Spark's mechanism for re-distributing data so that it’s grouped differently across partitions.
</li>
<li>
Data is often distributed unevenly across partitions.
</li>
<li>
<b>repartition</b> and <b>coalesce</b> operators can repartition a dataset.
</li>
<li>Switch to Mastering Apache Spark 2
<ul>
<li><a href="https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-rdd-dependencies.html">RDD Dependencies</a></li>
<li><a href="https://jaceklaskowski.gitbooks.io/mastering-apache-spark/spark-rdd-shuffle.html">RDD Shuffle</a></li>
</ul>
</li>
</ol>
</section>
<section>
<section id="dagscheduler">
<h2>DAGScheduler</h2>
<img width="60%" src="images/dagscheduler-rdd-partitions-job-resultstage.png" style="border: 0">
</section>
<section>
<h2>Jobs</h2>
<img width="70%" src="images/rdd-job-partitions.png" style="border: 0">
</section>
<section>
<h2>Stages</h2>
<img width="70%" src="images/dagscheduler-stages.png" style="border: 0">
</section>
</section>
<section id="tasks">
<h2>Tasks</h2>
<img width="100%" src="images/stage-tasks.png" style="border: 0">
</section>
<section style="text-align: left" data-markdown id="questions">
<textarea data-template>
# Questions?
* Read [The Internals of Apache Spark](https://bit.ly/apache-spark-internals)
* Read [The Internals of Spark SQL](https://bit.ly/spark-sql-internals)
* Read [The Internals of Spark Structured Streaming](https://bit.ly/spark-structured-streaming)
* Follow [@jaceklaskowski](https://twitter.com/jaceklaskowski) on twitter
* Upvote [my questions and answers on StackOverflow](http://stackoverflow.com/users/1305344/jacek-laskowski)
</textarea>
</section>
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