我正在开发一个程序，该程序从 mqtt 代理获取 gps 数据并将其加载到 hadoop 集群中。在尝试将数据写入 hdfs 时，我得到了 IOException。以下是完整的堆栈跟踪:

java.io.IOException: Failed on local exception: com.google.protobuf.InvalidProtocolBufferException: Message missing required fields: callId, status; Host Details : local host is: "quickstart.cloudera/192.168.25.170"; destination host is: "quickstart.cloudera":8020; 
    at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:765)
    at org.apache.hadoop.ipc.Client.call(Client.java:1165)
    at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:184)
    at com.sun.proxy.$Proxy7.create(Unknown Source)
    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.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:165)
    at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:84)
    at com.sun.proxy.$Proxy7.create(Unknown Source)
    at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.create(ClientNamenodeProtocolTranslatorPB.java:187)
    at org.apache.hadoop.hdfs.DFSOutputStream.<init>(DFSOutputStream.java:1250)
    at org.apache.hadoop.hdfs.DFSOutputStream.newStreamForCreate(DFSOutputStream.java:1269)
    at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1063)
    at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1021)
    at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:232)
    at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:75)
    at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:806)
    at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:787)
    at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:686)
    at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:675)
    at com.mqttHadoopLoader.hadoop.MqttLoader.HdfsWriter.writeToHdfs(HdfsWriter.java:19)
    at com.mqttHadoopLoader.hadoop.MqttLoader.MqttDataLoader.messageArrived(MqttDataLoader.java:43)
    at org.eclipse.paho.client.mqttv3.internal.CommsCallback.handleMessage(CommsCallback.java:354)
    at org.eclipse.paho.client.mqttv3.internal.CommsCallback.run(CommsCallback.java:162)
    at java.lang.Thread.run(Thread.java:748)
Caused by: com.google.protobuf.InvalidProtocolBufferException: Message missing required fields: callId, status
    at com.google.protobuf.UninitializedMessageException.asInvalidProtocolBufferException(UninitializedMessageException.java:81)
    at org.apache.hadoop.ipc.protobuf.RpcPayloadHeaderProtos$RpcResponseHeaderProto$Builder.buildParsed(RpcPayloadHeaderProtos.java:1094)
    at org.apache.hadoop.ipc.protobuf.RpcPayloadHeaderProtos$RpcResponseHeaderProto$Builder.access$1300(RpcPayloadHeaderProtos.java:1028)
    at org.apache.hadoop.ipc.protobuf.RpcPayloadHeaderProtos$RpcResponseHeaderProto.parseDelimitedFrom(RpcPayloadHeaderProtos.java:986)
    at org.apache.hadoop.ipc.Client$Connection.receiveResponse(Client.java:850)
    at org.apache.hadoop.ipc.Client$Connection.run(Client.java:781)

似乎是在我尝试创建 OutputStream 时发生错误，但很难说，因为我的 eclipse 调试器无法正常工作(它说它无法连接到 VM，我已经尝试了许多修复在 stackoverflow 上发布)。这是我的 HdfsWriter 代码:

String destFile = "hdfs://127.0.0.0.1:8020/gpsData/output/gps_data.txt";
 //Note *this is just a placeholder IP address for the purpose of this post. I do have the fully correct IP address for the program. 

    public void writeToHdfs(String gpsInfo) {
        try {
            Configuration conf = new Configuration();
            System.out.println("Connecting to -- " + conf.get("fs.defaultFS"));

            FileSystem fs = FileSystem.get(URI.create(destFile), conf);
            System.out.println(fs.getUri());

            // Error seems to occur here
            OutputStream outStream = fs.create(new Path(destFile));

            byte[] messageByt = gpsInfo.getBytes();
            outStream.write(messageByt);
            outStream.close();

            System.out.println(destFile + " copied to HDFS");

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

这是调用 HdfsWriter 的 mqtt 方法:

public void messageArrived(String topic, MqttMessage message)
        throws Exception {
            System.out.println(message);
            HdfsWriter hdfsWriter = new HdfsWriter();
            hdfsWriter.writeToHdfs(message.toString());
    }

我对 hadoop 还是很陌生，所以任何帮助都会很棒。

更新 我的调试工作正常，可以明确地告诉您每当我尝试调用 FileSystem 方法时都会发生错误。例如，错误也会由 fs.exists(pt) 和 fs.setReplication() 触发。

最佳答案

我相信使用 google protobuf 库的 hdfs。而且您的客户端代码似乎使用了错误(不兼容)的 protobuf 版本。尝试朝这个方向挖掘。

关于java - 将文件写入 Hdfs 时出现 IOException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44891611/