Intro to Spark Lightning-fast cluster computing

What is Spark? Spark Overview: A fast and general-purpose cluster computing system.

What is Spark? Spark Overview: A fast and general-purpose cluster computing system. It provides high-level APIs in Java, Scala and Python, and an optimized engine that supports general execution graphs.

What is Spark? Spark Overview: A fast and general-purpose cluster computing system. It provides high-level APIs in Java, Scala and Python, and an optimized engine that supports general execution graphs. It supports a rich set of higher-level tools including: Spark SQL for SQL and structured data processing MLlib for machine learning GraphX for graph processing Spark Streaming for streaming processing

Apache Spark A Brief History

A Brief History: MapReduce circa 2004 – Google MapReduce: Simplified Data Processing on Large Clusters Jeffrey Dean and Sanjay Ghemawat MapReduce is a programming model and an associated implementation for processing and generating large data sets. research.google.com/archive/mapreduce.html

A Brief History: MapReduce circa 2004 – Google MapReduce: Simplified Data Processing on Large Clusters Jeffrey Dean and Sanjay Ghemawat MapReduce is a programming model and an associated implementation for processing and generating large data sets. research.google.com/archive/mapreduce.html

A Brief History: MapReduce MapReduce use cases showed two major limitations: 1. difficultly of programming directly in MR 2. performance bottlenecks, or batch not fitting the use cases In short, MR doesn’t compose well for large applications

A Brief History: Spark Developed in 2009 at UC Berkeley AMPLab, then open sourced in 2010, Spark has since become one of the largest OSS communities in big data, with over 200 contributors in 50+ organizations Unlike the various specialized systems, Spark’s goal was to generalize MapReduce to support new apps within same engine Lightning-fast cluster computing

A Brief History: Special Member Lately I've been working on the Databricks Cloud and Spark. I've been responsible for the architecture, design, and implementation of many Spark components. Recently, I led an effort to scale Spark and built a system based on Spark that set a new world record for sorting 100TB of data (in 23 Xin

A Brief History: Benefits Of Spark Speed Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk.

A Brief History: Benefits Of Spark Speed Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk.

A Brief History: Benefits Of Spark Speed Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk. Ease of Use Write applications quickly in Java, Scala or Python.

A Brief History: Benefits Of Spark Speed Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk. Ease of Use Write applications quickly in Java, Scala or Python. WordCount in 3 lines of Spark WordCount in 50+ lines of Java MR

A Brief History: Benefits Of Spark Speed Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk. Ease of Use Write applications quickly in Java, Scala or Python. Generality Combine SQL, streaming, and complex analytics.

A Brief History: Benefits Of Spark Speed Run programs up to 100x faster than Hadoop MapReduce in memory, or 10x faster on disk. Ease of Use Write applications quickly in Java, Scala or Python. Generality Combine SQL, streaming, and complex analytics.

A Brief History: Key distinctions for Spark vs. MapReduce handles batch, interactive, and real-time within a single framework programming at a higher level of abstraction more general: map/reduce is just one set of supported constructs functional programming / ease of use ⇒ reduction in cost to maintain large apps lower overhead for starting jobs less expensive shuffles …

TL;DR: Smashing The Previous Petabyte Sort Record databricks.com/blog/2014/11/05/spark-officially- sets-a-new-record-in-large-scale-sorting.html

TL;DR: Sustained Exponential Growth Spark is one of the most active Apache projects ohloh.net/orgs/apache

TL;DR: Spark Just Passed Hadoop in Popularity on Web datanami.com/2014/11/21/spark-just-passed- hadoop-popularity-web-heres/ In October Apache Spark (blue line) passed Apache Hadoop (red line) in popularity according to Google Trends In October Apache Spark (blue line) passed Apache Hadoop (red line) in popularity according to Google Trends

TL;DR: Spark Expertise Tops Median Salaries within Big Data oreilly.com/data/free/2014-data-science- salary-survey.csp

Apache Spark Spark Deconstructed

Spark Deconstructed: Scala Crash Course Spark was originally written in Scala, which allows concise function syntax and interactive use. Before deconstruct Spark, introduce to Scala.

Scala Crash Course: About Scala High-level language for the JVM Object oriented + functional programming Statically typed Comparable in speed to Java* Type inference saves us from having to write explicit types most of the time Interoperates with Java Can use any Java class (inherit from, etc.) Can be called from Java code

Scala Crash Course: Variables and Functions Declaring variables: var x: Int = 7 var x = 7 // type inferred val y = “hi” // read-only

Scala Crash Course: Variables and Functions Declaring variables: var x: Int = 7 var x = 7 // type inferred val y = “hi” // read-only Java equivalent: int x = 7; final String y = “hi”;

Scala Crash Course: Variables and Functions Declaring variables: var x: Int = 7 var x = 7 // type inferred val y = “hi” // read-only Functions: def square(x: Int): Int = x*x def square(x: Int): Int = { x*x } def announce(text: String) = { println(text) } Java equivalent: int x = 7; final String y = “hi”;

Scala Crash Course: Variables and Functions Declaring variables: var x: Int = 7 var x = 7 // type inferred val y = “hi” // read-only Functions: def square(x: Int): Int = x*x def square(x: Int): Int = { x*x } def announce(text: String) = { println(text) } Java equivalent: int x = 7; final String y = “hi”; Java equivalent: int square(int x) { return x*x; } void announce(String text) { System.out.println(text); }

Scala Crash Course: Scala functions (closures) (x: Int) => x + 2 // full version

Scala Crash Course: Scala functions (closures) (x: Int) => x + 2 // full version x => x + 2 // type inferred

Scala Crash Course: Scala functions (closures) (x: Int) => x + 2 // full version x => x + 2 // type inferred _ + 2 // placeholder syntax (each argument must be used exactly once)

Scala Crash Course: Scala functions (closures) (x: Int) => x + 2 // full version x => x + 2 // type inferred _ + 2 // placeholder syntax (each argument must be used exactly once) x => { // body is a block of code val numberToAdd = 2 x + numberToAdd }

Scala Crash Course: Scala functions (closures) (x: Int) => x + 2 // full version x => x + 2 // type inferred _ + 2 // placeholder syntax (each argument must be used exactly once) x => { // body is a block of code val numberToAdd = 2 x + numberToAdd } // Regular functions def addTwo(x: Int): Int = x + 2

Scala Crash Course: Collections processing Processing collections with functional programming val list = List(1, 2, 3)

Scala Crash Course: Collections processing Processing collections with functional programming val list = List(1, 2, 3) list.foreach(x => println(x)) // prints 1, 2, 3 list.foreach(println) // same

Scala Crash Course: Collections processing Processing collections with functional programming val list = List(1, 2, 3) list.foreach(x => println(x)) // prints 1, 2, 3 list.foreach(println) // same list.map(x => x + 2) // returns a new List(3, 4, 5) list.map(_ + 2) // same

Scala Crash Course: Collections processing Processing collections with functional programming val list = List(1, 2, 3) list.foreach(x => println(x)) // prints 1, 2, 3 list.foreach(println) // same list.map(x => x + 2) // returns a new List(3, 4, 5) list.map(_ + 2) // same list.filter(x => x % 2 == 1) // returns a new List(1, 3) list.filter(_ % 2 == 1) // same

Scala Crash Course: Collections processing Processing collections with functional programming val list = List(1, 2, 3) list.foreach(x => println(x)) // prints 1, 2, 3 list.foreach(println) // same list.map(x => x + 2) // returns a new List(3, 4, 5) list.map(_ + 2) // same list.filter(x => x % 2 == 1) // returns a new List(1, 3) list.filter(_ % 2 == 1) // same list.reduce((x, y) => x + y) // => 6 list.reduce(_ + _) // same

Scala Crash Course: Collections processing Functional methods on collections Method on Seq[T]Explanation map(f: T => U): Seq[U]Each element is result of f flatMap(f: T => Seq[U]): Seq[U]One to many map filter(f: T => Boolean): Seq[T]Keep elements passing f exists(f: T => Boolean): BooleanTrue if one element passes f forall(f: T => Boolean): BooleanTrue if all elements pass reduce(f: (T, T) => T): TMerge elements using f groupBy(f: T => K): Map[K, List[T]]Group elements by f sortBy(f: T => K): Seq[T]Sort elements …..

Spark Deconstructed: Log Mining Example // load error messages from a log into memory // then interactively search for various patterns // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() //

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() discussing the other part

Spark Deconstructed: Log Mining Example At this point, take a look at the transformed RDD operator graph: scala> errors.toDebugString res1: String = (2) FilteredRDD[2] at filter at :14 | log.txt MappedRDD[1] at textFile at :12 | log.txt HadoopRDD[0] at textFile at :12

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 discussing the other part

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 discussing the other part

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 read HDFS block Worker block 2 read HDFS block Worker block 3 read HDFS block discussing the other part

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 process, cache data cache 1 process, cache data cache 2 process, cache data cache 3 discussing the other part

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 cache 1 cache 2 cache 3 discussing the other part

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 cache 1 cache 2 cache 3 discussing the other part

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 cache 1 cache 2 cache 3 discussing the other part process from cache process from cache process from cache

Spark Deconstructed: Log Mining Example // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() Driver Worker block 1 Worker block 2 Worker block 3 cache 1 cache 2 cache 3 discussing the other part

Spark Deconstructed: Log Mining Example Looking at the RDD transformations and actions from another perspective… // load error messages from a log into memory // then interactively search for various patterns // base RDD val file = sc.textFile("hdfs://...") // transformed RDDs val errors = file.filter(line => line.contains("ERROR")) errors.cache() errors.count() // action errors.filter(_.contains("mysql")).count() // action errors.filter(_.contains("php")).count() // transformations action RDD value

Spark Deconstructed: Log Mining Example RDD // base RDD val file = sc.textFile("hdfs://...")

Spark Deconstructed: Log Mining Example transformations RDD val errors = file.filter(line => line.contains("ERROR")) errors.cache()

Spark Deconstructed: Live of a Spark Application TermMeaning ApplicationUser program built on Spark. Consists of a driver program and executors on the cluster. Driver ProgramThe process running the main() function of the application and creating the SparkContext Cluster ManagerAn external service for acquiring resources on the cluster (e.g. standalone manager, Mesos, YARN) Worker NodeAny node that can run application code in the cluster ExecutorA process launched for an application on a worker node, that runs tasks and keeps data in memory or disk storage across them. Each application has its own executors.

Spark Deconstructed: Live of a Spark Application TermMeaning TaskA unit of work that will be sent to one executor JobA parallel computation consisting of multiple tasks that gets spawned in response to a Spark action (e.g. save, collect); you'll see this term used in the driver's logs. StageEach job gets divided into smaller sets of tasks called stages that depend on each other (similar to the map and reduce stages in MapReduce); you'll see this term used in the driver's logs.

Spark Deconstructed: Live of a Spark Application

Apache Spark Spark Essential

Spark Essential: SparkContext First thing that a Spark program does is create a SparkContext object, which tells Spark how to access a cluster In the shell for either Scala or Python, this is the sc variable, which is created automatically Other programs must use a constructor to instantiate a new SparkContext Then in turn SparkContext gets used to create other variables

Spark Essential: SparkContext Scala: scala> sc res: spark.SparkContext = Python: >>> sc

Spark Essential: Master The master parameter for a SparkContext determines which cluster to use masterdescription local run Spark locally with one worker thread (no parallelism) local[k] run Spark locally with K worker threads (ideally set to # cores) spark://HOST:PORT connect to a Spark standalone cluster; PORT depends on config (7077 by default) mesos://HOST:PORT connect to a Mesos cluster; PORT depends on config (5050 by default)

Spark Essential: Master spark.apache.org/docs/latest/cluster- overview.html Worker Node Executor cache task Cluster Manager

Spark Essential: Clusters 1.master connects to a cluster manager to allocate resources across applications 2.acquires executors on cluster nodes – processes run compute tasks, cache data 3.sends app code to the executors 4.sends tasks for the executors to run Worker Node Executor cache task Cluster Manager

Spark Essential: RDD Resilient Distributed Datasets (RDD) are the primary abstraction in Spark – a fault-tolerant collection of elements that can be operated on in parallel There are currently two types: parallelized collections – take an existing Scala collection and run functions on it in parallel Hadoop datasets – run functions on each record of a file in Hadoop distributed file system or any other storage system supported by Hadoop

Spark Essential: RDD two types of operations on RDDs: transformations and actions transformations are lazy (not computed immediately) the transformed RDD gets recomputed when an action is run on it (default) however, an RDD can be persisted into storage in memory or disk

Spark Essential: RDD Scala: scala> val data = Array(1, 2, 3, 4, 5) data: Array[Int] = Array(1, 2, 3, 4, 5) scala> val distData = sc.parallelize(data) distData: spark.RDD[Int] = Python: >>> data = [1, 2, 3, 4, 5] >>> data [1, 2, 3, 4, 5] >>> distData = sc.parallelize(data) >>> distData ParallelCollectionRDD[0] at parallelize at PythonRDD.scala:229

Spark Essential: RDD Spark can create RDDs from any file stored in HDFS or other storage systems supported by Hadoop, e.g., local file system, Amazon S3, Hypertable, HBase, etc. Spark supports text files, SequenceFiles, and any other Hadoop InputFormat, and can also take a directory or a glob (e.g. /data/201404*) transformations action RDD value

Spark Essential: Transformations Transformations create a new dataset from an existing one All transformations in Spark are lazy: they do not compute their results right away – instead they remember the transformations applied to some base dataset optimize the required calculations recover from lost data partitions

Spark Essential: Transformations transformationdescription map(func) return a new distributed dataset formed by passing each element of the source through a function func filter(func) return a new dataset formed by selecting those elements of the source on which func returns true flatMap(func) similar to map, but each input item can be mapped to 0 or more output items (so func should return a Seq rather than a single item) sample(withReplacement, fraction, seed) sample a fraction fraction of the data, with or without replacement, using a given random number generator seed union(otherDataset) return a new dataset that contains the union of the elements in the source dataset and the argument distinct([numTasks])) return a new dataset that contains the distinct elements of the source dataset

Spark Essential: Transformations transformationdescription groupByKey([numTasks]) when called on a dataset of (K, V) pairs, returns a dataset of (K, Seq[V]) pairs reduceByKey(func, [numTasks]) when called on a dataset of (K, V) pairs, returns a dataset of (K, V) pairs where the values for each key are aggregated using the given reduce function sortByKey([ascending], [numTasks]) when called on a dataset of (K, V) pairs where K implements Ordered, returns a dataset of (K, V) pairs sorted by keys in ascending or descending order, as specified in the boolean scending argument join(otherDataset, [numTasks]) when called on datasets of type (K, V) and (K, W), returns a dataset of (K, (V, W)) pairs with all pairs of elements for each key cogroup(otherDataset, [numTasks]) when called on datasets of type (K, V) and (K, W), returns a dataset of (K, Seq[V], Seq[W]) tuples – also called groupWith cartesian(otherDataset) when called on datasets of types T and U, returns a dataset of (T, U) pairs (all pairs of elements)

Spark Essential: Actions actiondescription reduce(func) aggregate the elements of the dataset using a function func (which takes two arguments and returns one), and should also be commutative and associative so that it can be computed correctly in parallel collect() return all the elements of the dataset as an array at the driver program – usually useful after a filter or other operation that returns a sufficiently small subset of the data count() return the number of elements in the dataset first() return the first element of the dataset – similar to take(1) take(n) return an array with the first n elements of the dataset – currently not executed in parallel, instead the driver program computes all the elements takeSample(withReplacem ent, fraction, seed) return an array with a random sample of num elements of the dataset, with or without replacement, using the given random number generator seed

Spark Essential: Actions actiondescription saveAsTextFile(path) write the elements of the dataset as a text file (or set of text files) in a given directory in the local filesystem, HDFS or any other Hadoop-supported file system. Spark will call toString on each element to convert it to a line of text in the file saveAsSequenceFile(path) write the elements of the dataset as a Hadoop SequenceFile in a given path in the local filesystem, HDFS or any other Hadoop-supported file system. Only available on RDDs of key-value pairs that either implement Hadoop's Writable interface or are implicitly convertible to Writable (Spark includes conversions for basic types like Int, Double, String, etc). countByKey() only available on RDDs of type (K, V). Returns a `Map` of (K, Int) pairs with the count of each key foreach(func) run a function func on each element of the dataset – usually done for side effects such as updating an accumulator variable or interacting with external storage systems

Spark Essential: Persistence Spark can persist (or cache) a dataset in memory across operations Each node stores in memory any slices of it that it computes and reuses them in other actions on that dataset – often making future actions more than 10x faster The cache is fault-tolerant: if any partition of an RDD is lost, it will automatically be recomputed using the transformations that originally created it

Apache Spark Simple Spark Demo

Simple Spark Demo: WordCount Definition: This simple program provides a good test case for parallel processing, since it: requires a minimal amount of code demonstrates use of both symbolic and numeric values isn’t many steps away from search indexing serves as a “Hello World” for Big Data apps A distributed computing framework that can run WordCount efficiently in parallel at scale can likely handle much larger and more interesting compute problems count how often each word appears in a collection of text documents void map (String doc_id, String text): for each word w in segment(text): emit(w, "1"); void reduce (String word, Iterator group): int count = 0; for each pc in group: count += Int(pc); emit(word, String(count));

Simple Spark Demo: WordCount Scala: val file = sc.textFile("hdfs://...") val counts = file.flatMap(line => line.split(" ")).map(word => (word, 1)).reduceByKey(_ + _) counts.saveAsTextFile("hdfs://...") Python: from operator import add f = sc.textFile("hdfs://...") wc = f.flatMap(lambda x: x.split(' ')).map(lambda x: (x,1)).reduceByKey(add) wc.saveAsTextFile("hdfs://...")

Simple Spark Demo: WordCount Scala: val file = sc.textFile("hdfs://...") val counts = file.flatMap(line => line.split(" ")).map(word => (word, 1)).reduceByKey(_ + _) counts.saveAsTextFile("hdfs://...") Python: from operator import add f = sc.textFile("hdfs://...") wc = f.flatMap(lambda x: x.split(' ')).map(lambda x: (x,1)).reduceByKey(add) wc.saveAsTextFile("hdfs://...") Checkpoint: how many “Spark” keywords?

Simple Spark Demo: Estimate Pi Next, try using a Monte Carlo method to estimate the value of Pi wikipedia.org/wiki/Monte_Carlo_method

Simple Spark Demo: Estimate Pi val count = spark.parallelize(1 to NUM_SAMPLES).map{i => val x = Math.random() val y = Math.random() if (x*x + y*y < 1) 1 else 0 }.reduce(_ + _) println("Pi is roughly " * count / NUM_SAMPLES)

Simple Spark Demo: Estimate Pi val count = spark.parallelize(1 to NUM_SAMPLES).map{i => val x = Math.random() val y = Math.random() if (x*x + y*y < 1) 1 else 0 }.reduce(_ + _) println("Pi is roughly " * count / NUM_SAMPLES) Checkpoint: how estimate do you get for Pi?

Apache Spark Spark SQL

Reference: Spark Overview: Scala Learning(Tutorials): Spark SQL 源码分析 :