玩转Cassandra Netty Server空指针异常

Question

嗨，我正在使用 playframework 等技术，

spark = "2.3.1",
akka = "2.4.7"
hadoop = "2.7.7"
spring = "4.2.6.RELEASE",
spark-cassandra-connector 2.0.9 ,
cassandra-driver-core 3.0.6

我在项目清理编译时低于警告

c.d.d.c.NettyUtil - Found Netty's native epoll transport, but not running on linux-based operating system. Using NIO instead

 io.netty:netty-handler:4.0.56.Final is selected over 4.0.36.Final
     +- com.datastax.cassandra:cassandra-driver-core:3.5.1 (depends on 4.0.56.Final)
     +- com.typesafe.netty:netty-reactive-streams:1.0.6    (depends on 4.0.36.Final)
     +- io.netty:netty-codec-http:4.0.36.Final             (depends on 4.0.36.Final)

在 sbt 运行时，低于错误

java.lang.NullPointerException
        at io.netty.channel.group.DefaultChannelGroup.add(DefaultChannelGroup.java:146)
        at play.core.server.NettyServer.bind(NettyServer.scala:140)
        at play.core.server.NettyServer.play$core$server$NettyServer$$bindChannel(NettyServer.scala:224)
        at play.core.server.NettyServer$$anonfun.apply(NettyServer.scala:216)
        at play.core.server.NettyServer$$anonfun.apply(NettyServer.scala:216)
        at scala.Option.map(Option.scala:146)
        at play.core.server.NettyServer.<init>(NettyServer.scala:216)
        at play.core.server.NettyServerProvider.createServer(NettyServer.scala:279)
        at play.core.server.NettyServerProvider.createServer(NettyServer.scala:278)
        at play.core.server.DevServerStart$$anonfun$mainDev.apply(DevServerStart.scala:225)
        at play.core.server.DevServerStart$$anonfun$mainDev.apply(DevServerStart.scala:61)
        at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
        at play.core.server.DevServerStart$.mainDev(DevServerStart.scala:60)
        at play.core.server.DevServerStart$.mainDevHttpMode(DevServerStart.scala:50)
        at play.core.server.DevServerStart.mainDevHttpMode(DevServerStart.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at play.runsupport.Reloader$.startDevMode(Reloader.scala:234)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$$anonfun$apply$$anonfun$apply.devModeServer$lzycompute(PlayRun.scala:74)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$$anonfun$apply$$anonfun$apply.play$sbt$run$PlayRun$$anonfun$$anonfun$$anonfun$$devModeServer(PlayRun.scala:74)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$$anonfun$apply$$anonfun$apply.apply(PlayRun.scala:100)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$$anonfun$apply$$anonfun$apply.apply(PlayRun.scala:53)
        at scala.Function1$$anonfun$compose.apply(Function1.scala:47)
        at sbt.$tilde$greater$$anonfun$$u2219.apply(TypeFunctions.scala:40)
        at sbt.std.Transform$$anon.work(System.scala:63)
        at sbt.Execute$$anonfun$submit$$anonfun$apply.apply(Execute.scala:228)
        at sbt.Execute$$anonfun$submit$$anonfun$apply.apply(Execute.scala:228)
        at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
        at sbt.Execute.work(Execute.scala:237)
        at sbt.Execute$$anonfun$submit.apply(Execute.scala:228)
        at sbt.Execute$$anonfun$submit.apply(Execute.scala:228)
        at sbt.ConcurrentRestrictions$$anon$$anonfun.apply(ConcurrentRestrictions.scala:159)
        at sbt.CompletionService$$anon.call(CompletionService.scala:28)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
[error] (*:playRun) java.lang.reflect.InvocationTargetException

如何解决网络问题？是不是版本不匹配的问题？？

Answer 1

如果您也在这里提供一些代码（尤其是您初始化 netty 的代码），我可能会更有帮助，但您面临的问题是在非 Linux 中使用 Linux 本机传输系统。尝试找到你使用 Epoll 的地方，并用所有操作系统都支持的 NIO 替换它们。如果您运行您的应用也在 Linux 上，那么您应该检查是否可以将 Epoll 与 Epoll.isAvailable()

一起使用

Answer 2

此问题与 Cassandra 有关，因此，目前我使用的是阴影版的 cassandra。出现问题是因为应用程序使用了另一个 netty 版本，所以为了避免冲突，提供了 cassandra 的阴影版本 jar，它将 Netty 类捆绑在不同的包

下

"com.datastax.cassandra" % "cassandra-driver-core" % "3.1.4" exclude("io.netty", "*") classifier "shaded"

供参考：https://docs.datastax.com/en/developer/java-driver/3.1/manual/shaded_jar/

另外，您可以使用 dependencyOverrides:

要更改所选版本，请添加覆盖：

dependencyOverrides += "" % "" % ""

参考：https://www.scala-sbt.org/1.x/docs/Library-Management.html#Overriding+a+version

玩转Cassandra Netty Server空指针异常

Play Cassandra Netty Server null pointer exception

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netty

apache-spark

cassandra-driver