Question

嗨，我正在将Playframework与诸如，

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

在进行项目干净编译时，我正处于警告之下

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$1.apply(NettyServer.scala:216)
        at play.core.server.NettyServer$$anonfun$1.apply(NettyServer.scala:216)
        at scala.Option.map(Option.scala:146)
        at play.core.server.NettyServer.<init>(NettyServer.scala:216)
        at play.core.server.NettyServerProvider.createServer(NettyServer.scala:279)
        at play.core.server.NettyServerProvider.createServer(NettyServer.scala:278)
        at play.core.server.DevServerStart$$anonfun$mainDev$1.apply(DevServerStart.scala:225)
        at play.core.server.DevServerStart$$anonfun$mainDev$1.apply(DevServerStart.scala:61)
        at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
        at play.core.server.DevServerStart$.mainDev(DevServerStart.scala:60)
        at play.core.server.DevServerStart$.mainDevHttpMode(DevServerStart.scala:50)
        at play.core.server.DevServerStart.mainDevHttpMode(DevServerStart.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at play.runsupport.Reloader$.startDevMode(Reloader.scala:234)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.devModeServer$lzycompute$1(PlayRun.scala:74)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.play$sbt$run$PlayRun$$anonfun$$anonfun$$anonfun$$devModeServer$1(PlayRun.scala:74)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.apply(PlayRun.scala:100)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.apply(PlayRun.scala:53)
        at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
        at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:40)
        at sbt.std.Transform$$anon$4.work(System.scala:63)
        at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:228)
        at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:228)
        at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
        at sbt.Execute.work(Execute.scala:237)
        at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:228)
        at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:228)
        at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:159)
        at sbt.CompletionService$$anon$2.call(CompletionService.scala:28)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.Executors$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？是否存在版本不匹配的问题？

Answer 1

此问题与Cassandra有关，因此，到目前为止，我使用的阴影版本为cassandra。发生问题是因为该应用程序使用另一个Netty版本，所以为避免这种冲突，请提供cassandra的阴影版本jar，该罐将Netty类捆绑在不同的软件包下

“ com.datastax.cassandra”％“ cassandra-driver-core”％“ 3.1.4” exclude（“ io.netty”，“ *”）分类器“阴影”

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

也，您可以使用dependencyOverrides：

要更改所选版本，请添加替代项：

dependencyOverrides + =“”％“”％“”

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

Answer 2

如果您在此处还提供了一些代码（尤其是初始化netty的代码），我可能会更有帮助，但是您面临的问题是在非Linux系统中使用Linux本机传输。尝试找到使用Epoll的地方，并用所有操作系统都支持的NIO替换它们。如果您也在Linux上运行应用程序，则应检查是否可以将Epoll与Epoll.isAvailable（）

一起使用

播放Cassandra Netty Server空指针异常

2 个答案: