侯上校

[root@cluster spark-1.5.1]# mvn -Dhadoop.version=2.6.0-cdh5.4.0 -Dscala-2.10.4 -Phive -Dmaven.test.skip=true clean package   [INFO] Replacing original artifact with shaded artifact. [INFO] Replac...

转自：http://my.oschina.net/scipio/blog/282794   一、概念 协变和逆变是描述在集合中的多态关系与原来类型多态关系之间的关系。如果T1是T的子类，那么Container[T1]是不是Container[T]的子类呢？Variance注释允许你在类继承和多态类型之间表达下面的这些关系： * covariant(协变),[+T],C...

...... [INFO] Including org.spark-project.spark:unused:jar:1.0.0 in the shaded jar. [WARNING] hadoop-yarn-common-2.6.0.jar, hadoop-yarn-api-2.6.0.jar define 3 overlapping classes: [WARNING] - o...

Spark2.0.0神器

/** * An interface to represent clocks, so that they can be mocked out in unit tests. */ private[spark] trait Clock { def getTimeMillis(): Long def waitTillTime(targetTime: Long): Long } ...