为什么我可以在不提交火花的情况下直接在Eclipse中运行spark应用 [英] why can i run spark app in eclipse directly without spark-submit

问题描述

1。我的spark（独立）集群：spmaster，spslave1，spslave2

1.My spark(standalone) cluster: spmaster,spslave1,spslave2

2。对于我简单的spark应用程序，它从mysql中选择了一些记录。

2.For my simple spark app which selects some records from mysql.

public static void main(String[] args) {
    SparkConf conf = new SparkConf()
            .setMaster("spark://spmaster:7077")
            .setAppName("SparkApp")
            .set("spark.driver.extraClassPath","/usr/lib/spark-1.6.1-bin-hadoop2.6/lib/mysql-connector-java-5.1.24.jar")  //the driver jar was uploaded to all nodes
            .set("spark.executor.extraClassPath","/usr/lib/spark-1.6.1-bin-hadoop2.6/lib/mysql-connector-java-5.1.24.jar");
    JavaSparkContext sc = new JavaSparkContext(conf);
    SQLContext sqlContext = new SQLContext(sc);
    String url = "jdbc:mysql://192.168.31.43:3306/mytest";
    Map<String, String> options = new HashMap<String, String>();
    options.put("url", url);
    options.put("dbtable", "mytable");
    options.put("user", "root");
    options.put("password", "password");
    DataFrame jdbcDF = sqlContext.read().format("jdbc").options(options)
            .load();
    jdbcDF.registerTempTable("c_picrecord");
    DataFrame sql = sqlContext.sql("select * from mytable limit 10");
    sql.show();  // **show the result on eclipse console**
    sc.close();
}

3。我的问题：当我右键单击-> 以 Java应用程序运行，它可以成功运行，我可以在webUI < spark上找到工作： // spmaster：7077> 。我不了解其工作原理，使用 spark-submit.sh 有什么区别。

3.My question : when i right click->run as 'Java Application', it works successfully, and i can find the job on webUI<spark://spmaster:7077>.I don't undersatand how it works , and what is the different between with using spark-submit.sh.

推荐答案

当我们使用 spark-submit.sh 提交申请时，然后默认情况下，火花提交已经创建了Spark上下文（aka 驱动程序）。

When we use spark-submit.sh for submitting application, then spark-submit already created Spark Context (aka Driver) by default.

但是当我们使用Java API（ JavaSparkContext ）连接主服务器，则Java应用程序将成为 Driver 。通过使用该驱动程序，所有应用程序/作业都将提交给母版。

But when we use Java API (JavaSparkContext) to connect master, then Java application will become Driver. And by using this Driver all application/job will submitted to master.

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