{"id":16721677,"url":"https://github.com/zoltan-nz/learning-spark","last_synced_at":"2026-04-17T06:32:16.877Z","repository":{"id":144596585,"uuid":"136719712","full_name":"zoltan-nz/learning-spark","owner":"zoltan-nz","description":"Playing with Apache Spark","archived":false,"fork":false,"pushed_at":"2018-06-17T11:10:59.000Z","size":108,"stargazers_count":1,"open_issues_count":0,"forks_count":0,"subscribers_count":0,"default_branch":"master","last_synced_at":"2025-10-23T22:32:22.371Z","etag":null,"topics":["apache-spark","java","map-reduce","spark"],"latest_commit_sha":null,"homepage":"","language":"Java","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/zoltan-nz.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2018-06-09T12:02:41.000Z","updated_at":"2018-06-17T11:11:00.000Z","dependencies_parsed_at":null,"dependency_job_id":"e2b2ac9a-0773-413c-ad36-d0264258946f","html_url":"https://github.com/zoltan-nz/learning-spark","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/zoltan-nz/learning-spark","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/zoltan-nz%2Flearning-spark","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/zoltan-nz%2Flearning-spark/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/zoltan-nz%2Flearning-spark/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/zoltan-nz%2Flearning-spark/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/zoltan-nz","download_url":"https://codeload.github.com/zoltan-nz/learning-spark/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/zoltan-nz%2Flearning-spark/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":31918479,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-04-16T18:22:33.417Z","status":"online","status_checked_at":"2026-04-17T02:00:06.879Z","response_time":62,"last_error":null,"robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["apache-spark","java","map-reduce","spark"],"created_at":"2024-10-12T22:31:51.042Z","updated_at":"2026-04-17T06:32:16.847Z","avatar_url":"https://github.com/zoltan-nz.png","language":"Java","funding_links":[],"categories":[],"sub_categories":[],"readme":"# Playing with Apache Spark\n\n## First Step: Running Spark development environment\n\nStart with Quick Start from the official documentation: https://spark.apache.org/docs/latest/quick-start.html\n\nLet's implement the Self-Contained Application.\n\nSource: https://spark.apache.org/docs/latest/quick-start.html#self-contained-applications\n\n1. Create a new Maven project.\n2. Add the code from the documentation.\n3. Save a huge sample text in your `resources` folder.\n\n**Issue #1**: The code will not work without a little change.\n\nWe have to use type casting in the lambda function.\n\n`(FilterFunction\u003cString\u003e)`\n\n**Issue #2**: It is much easier to debug your code if you run Spark server in local mode.\n\n* Allowed Master URLs: https://spark.apache.org/docs/latest/submitting-applications.html#master-urls\n\n`.config(\"spark.master\", \"local\")`\n\nThe right code:\n\n```java\npackage nz.zoltan;\n\nimport org.apache.spark.api.java.function.FilterFunction;\nimport org.apache.spark.sql.Dataset;\nimport org.apache.spark.sql.SparkSession;\n\n/**\n * Hello world!\n */\npublic class App {\n    public static void main(String[] args) {\n\n        String logFile = \"SimpleApp/src/main/resources/sample-text/toldi.txt\"; // Should be some file on your system\n        SparkSession spark = SparkSession\n                .builder()\n                .appName(\"Simple Application\")\n                .config(\"spark.master\", \"local\")\n                .getOrCreate();\n        Dataset\u003cString\u003e logData = spark.read().textFile(logFile).cache();\n\n        long numAs = logData.filter((FilterFunction\u003cString\u003e) s -\u003e s.contains(\"a\")).count();\n        long numBs = logData.filter((FilterFunction\u003cString\u003e) s -\u003e s.contains(\"b\")).count();\n        long numToldis = logData.filter((FilterFunction\u003cString\u003e) s -\u003e s.contains(\"Toldi\")).count();\n\n\n        System.out.println(\"Lines with a: \" + numAs + \", lines with b: \" + numBs + \", lines with Toldi: \" + numToldis);\n\n        spark.stop();\n    }\n}\n```\n\nMore details about single developer mode: https://stackoverflow.com/questions/38008330/spark-error-a-master-url-must-be-set-in-your-configuration-when-submitting-a\n\n**Master URLs**: https://spark.apache.org/docs/latest/submitting-applications.html#master-urls\n\n## Second Step: Using RDD\n\nRead this: https://spark.apache.org/docs/latest/rdd-programming-guide.html\n\nMore details in [`RDDApp`](RDDApp/src/main/java/nz/zoltan/RDDApp.java)\n\nCounting and sorting words in a huge text file:\n\n```java\nJavaRDD\u003cString\u003e lines = sc.textFile(BIG_TEXT_FILE_LOCATION).cache();\n\nJavaRDD\u003cString\u003e words = lines.flatMap(line -\u003e Arrays.asList(line.split(\" \")).iterator());\nJavaPairRDD\u003cString, Integer\u003e wordsWithOne = words.mapToPair(word -\u003e new Tuple2\u003c\u003e(word, 1));\nJavaPairRDD\u003cString, Integer\u003e wordsWithCount = wordsWithOne.reduceByKey((a, b) -\u003e a + b);\nJavaPairRDD\u003cInteger, String\u003e countsWithWord = wordsWithCount.mapToPair(Tuple2::swap);\nJavaPairRDD\u003cInteger, String\u003e sortedCounts = countsWithWord.sortByKey();\n\nsortedCounts.collect().forEach((tuple) -\u003e System.out.println(tuple._2 + \": \" + tuple._1));\n```\n\n## Notes in terms of Maven\n\n* Using multi module maven structure. More information about building a multi module maven project: https://books.sonatype.com/mvnex-book/reference/multimodule.html\n* Add `maven-exec-plugin` to run the app\n\n## Using Docker\n\n**Creating a Docker file**\n\nI created a lightweight Java and Maven container.\n\nInspirations:\n* Java installation based on this [Dockerfile](https://github.com/docker-library/openjdk/blob/dd54ae37bc44d19ecb5be702d36d664fed2c68e4/8/jdk/alpine/Dockerfile)\n* Maven installation based on this [Dockerfile](https://github.com/Zeika/alpine-maven/blob/master/jdk8/Dockerfile)\n* Docker-maven [Dockerfile](https://github.com/carlossg/docker-maven)\n\n```java\n$ docker build -t learning-spark .\n$ docker run learning-spark:latest mvn --pl SimpleApp exec:java \n```","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fzoltan-nz%2Flearning-spark","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fzoltan-nz%2Flearning-spark","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fzoltan-nz%2Flearning-spark/lists"}