Apache flink（稳定版 1.6.2）不起作用

Question

近日，apache flink 稳定版（1.6.2）发布。我读了this instruction。但是当我运行以下命令时：

./bin/flink run examples/streaming/SocketWindowWordCount.jar --port 9000

我收到以下错误：

 The program finished with the following exception:

org.apache.flink.client.program.ProgramInvocationException: Job failed. (JobID: 264564a337d4c6705bde681b34010d28)
    at org.apache.flink.client.program.rest.RestClusterClient.submitJob(RestClusterClient.java:268)
    at org.apache.flink.client.program.ClusterClient.run(ClusterClient.java:486)
    at org.apache.flink.streaming.api.environment.StreamContextEnvironment.execute(StreamContextEnvironment.java:66)
    at org.apache.flink.streaming.examples.socket.SocketWindowWordCount.main(SocketWindowWordCount.java:92)
    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:498)
    at org.apache.flink.client.program.PackagedProgram.callMainMethod(PackagedProgram.java:529)
    at org.apache.flink.client.program.PackagedProgram.invokeInteractiveModeForExecution(PackagedProgram.java:421)
    at org.apache.flink.client.program.ClusterClient.run(ClusterClient.java:426)
    at org.apache.flink.client.cli.CliFrontend.executeProgram(CliFrontend.java:816)
    at org.apache.flink.client.cli.CliFrontend.runProgram(CliFrontend.java:290)
    at org.apache.flink.client.cli.CliFrontend.run(CliFrontend.java:216)
    at org.apache.flink.client.cli.CliFrontend.parseParameters(CliFrontend.java:1053)
    at org.apache.flink.client.cli.CliFrontend.lambda$main$11(CliFrontend.java:1129)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:422)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1836)
    at org.apache.flink.runtime.security.HadoopSecurityContext.runSecured(HadoopSecurityContext.java:41)
    at org.apache.flink.client.cli.CliFrontend.main(CliFrontend.java:1129)
Caused by: org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
    at org.apache.flink.runtime.jobmaster.JobResult.toJobExecutionResult(JobResult.java:146)
    at org.apache.flink.client.program.rest.RestClusterClient.submitJob(RestClusterClient.java:265)
    ... 20 more
Caused by: java.net.ConnectException: Connection refused (Connection refused)
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at org.apache.flink.streaming.api.functions.source.SocketTextStreamFunction.run(SocketTextStreamFunction.java:96)
    at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:94)
    at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:58)
    at org.apache.flink.streaming.runtime.tasks.SourceStreamTask.run(SourceStreamTask.java:99)
    at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:300)
    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:711)
    at java.lang.Thread.run(Thread.java:748)

我找到了这个链接：Flink program cannot submit when i follow flink-1.4's quickstart and use "./bin/flink run examples/streaming/SocketWindowWordCount.jar --port 9000"。然而，它没有帮助。我尝试在mac os 和ubuntu 上使用Flink 1.6.2 with Hadoop® 2.8 和Flink 1.5.5 with Hadoop® 2.8。但我也遇到了同样的错误。

Answer 1

对我来说很好用。我能看到的唯一区别是我使用的是没有 hadoop 的 Flink 版本，但我怀疑这是问题所在。

java.net.ConnectException: Connection refused 通常表示 9000 端口上没有服务监听。你应该在这个端口上运行 netcat 通过

$ nc -l 9000

（请参阅https://ci.apache.org/projects/flink/flink-docs-stable/quickstart/setup_quickstart.html#run-the-example）。如果 netcat 正在运行，但它不工作，也许尝试另一个端口？检查所有日志文件以获取更多线索也可能会有所帮助。

Answer 2

我通过阅读nc -h（在 Linux 中）解决了这个烦人的问题：

connect to somewhere:   nc [-options] hostname port[s] [ports] ... 
listen for inbound: nc -l -p port [-options] [hostname] [port]

所以对于监听端口，-p 是必须的，我尝试了以下命令：

nc -l -p 9000

它奏效了。