# RPC

这个模块是1.2没有的，应该是1.4才加入的 参见 Standardize internal RPC interface 不知道他们为啥把这个RPC框架放在这么重要位置，本来不都是用的Akka么

1.6 加入了NettyRpc 见Provide an alternative RPC implementation based on the network transport module

原来还是兼容性的问题: "A lot of Spark user applications are using (or want to use) Akka. Akka as a whole can contribute great architectural simplicity and uniformity. However, because Spark depends on Akka, it is not possible for users to rely on different versions, and we have received many requests in the past asking for help about this specific issue. For example, Spark Streaming might be used as the receiver of Akka messages - but our dependency on Akka requires the upstream Akka actors to also use the identical version of Akka. Since our usage of Akka is limited (mainly for RPC and single-threaded event loop), we can replace it with alternative RPC implementations and a common event loop in Spark."

2.0要全面替代 https://issues.apache.org/jira/browse/SPARK-5293 不知道稳定性怎么样，看样子要稳定一阵子