scala - 使用SBT构建Scala/Spark项目时的警告

Question

我正在尝试使用以下build.sbt在IntelliJ Idea中构建一个Scala / Spark项目:

name := "try"

version := "1.0"

scalaVersion := "2.11.8"

val sparkVersion = "2.2.0"

resolvers ++= Seq(
  "apache-snapshots" at "http://repository.apache.org/snapshots/"
)

libraryDependencies ++= Seq(
  "org.apache.spark" %% "spark-core" % sparkVersion,
  "org.apache.spark" %% "spark-sql" % sparkVersion,
  "org.apache.spark" %% "spark-mllib" % sparkVersion,
  "org.apache.spark" %% "spark-streaming" % sparkVersion,
  "org.apache.spark" %% "spark-hive" % sparkVersion
)

并得到一堆警告:

8/6/17
1:29 PM SBT project import
                [warn] Found version conflict(s) in library dependencies; some are suspected to be binary incompatible:
                [warn]  * io.netty:netty:3.9.9.Final is selected over {3.6.2.Final, 3.7.0.Final}
                [warn]      +- org.apache.spark:spark-core_2.11:2.2.0             (depends on 3.9.9.Final)
                [warn]      +- org.apache.zookeeper:zookeeper:3.4.6               (depends on 3.6.2.Final)
                [warn]      +- org.apache.hadoop:hadoop-hdfs:2.6.5                (depends on 3.6.2.Final)
                [warn]  * commons-net:commons-net:2.2 is selected over 3.1
                [warn]      +- org.apache.spark:spark-core_2.11:2.2.0             (depends on 2.2)
                [warn]      +- org.apache.hadoop:hadoop-common:2.6.5              (depends on 3.1)
                [warn]  * com.google.guava:guava:11.0.2 is selected over {12.0.1, 16.0.1}
                [warn]      +- org.apache.hadoop:hadoop-yarn-client:2.6.5         (depends on 11.0.2)
                [warn]      +- org.apache.hadoop:hadoop-yarn-api:2.6.5            (depends on 11.0.2)
                [warn]      +- org.apache.hadoop:hadoop-yarn-common:2.6.5 

我有几个问题，也许很愚蠢:

有没有更好的方法来构造build.sbt(例如添加其他解析器？)，以便摆脱警告？

我是否应该关心警告？

Answer 1

Is there a better way to structure build.sbt (add other resolvers e.g.?), so that I can get rid off the warnings?

一种方法是手动告诉sbt您喜欢哪种依赖关系:

dependencyOverrides ++= Set(
  "io.netty" % "netty" % "3.9.9.Final",
  "commons-net" % "commons-net" % "2.2",
  "com.google.guava" % "guava" % "11.0.2"
)

我还建议阅读有关 conflict management in sbt的信息。

Should I care about warnings at all?

在您的情况下-不，因为您的冲突源于仅使用同一版本下发布的与 Spark 相关的 Artifact 。 Spark是一个拥有大量用户群的项目，由于传递依赖而引入jar jar的可能性相当低(尽管从技术上讲不能保证)。

在一般情况下-也许。通常，在大多数情况下都可以，但是出现问题的可能性很小，可能需要仔细的手动依赖性解决方案(如果可能的话)。在这些情况下，在运行应用程序并遇到诸如类丢失，方法丢失，方法签名不匹配或某些与反射相关的问题之类的问题之前，很难分辨出是否存在问题。