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问题： 在Eclipse中跑一个Spark的算Pi例子。报错A master URL must be set in your configuration描述:
spark
ERROR SparkContext: Error initializing SparkContext.org.apache.spark.SparkException: A master URL must be set in your configuration
at org.apache.spark.SparkContext.
at org.apache.spark.api.java.JavaSparkContext.
at org.apache.spark.examples.JavaSparkPi.main(JavaSparkPi.java:37)
15/10/28 22:01:15 INFO SparkContext: Successfully stopped SparkContext
Exception in thread "main" org.apache.spark.SparkException: A master URL must be set in your configuration
at org.apache.spark.SparkContext.
at org.apache.spark.api.java.JavaSparkContext.
at org.apache.spark.examples.JavaSparkPi.main(JavaSparkPi.java:37)
我注意到了A master URL must be set in your configuration。于是我加上了setMaster：
SparkConf sparkConf = new SparkConf().setAppName("JavaSparkPi").setMaster("spark://master:7077");
加了setMaster（"spark://master:7077"）以后报错还是这，没有变。所以我想问这是什么情况？为什么会出现Error initializing SparkContext？ 多谢指教！