来自 java 的异常“：org.apache.hadoop.ipc.RpcException：RPC 响应超出最大数据长度”

Question

我正在尝试从桌面 Eclipse 中运行的 Java 程序连接到远程 HDFS。我能够连接。但在尝试读取数据时出现此异常：

原因：org.apache.hadoop.ipc.RpcException：RPC 响应超出最大数据量

有人可以帮忙解决这个问题吗？

我有一个非常基本的代码用于读取测试数据。错误来自 hdfs.open();

FileSystem hdfs =null;
    String uriPath = "hdfs://" + Constants.HOST + ":" + Constants.PORT+ "/test/hello_world.txt";
    String hadoopBase ="hdfs://" + Constants.HOST + ":" + Constants.PORT;
    Configuration conf = new Configuration();
    conf.set("fs.default.name", hadoopBase);
    URI uri;
    InputStream inputStream = null;
    try {
        uri = new URI(uriPath);
        hdfs =  FileSystem.get(uri, conf);
        Path path = new Path(uri);
        inputStream = hdfs.open(path);
        IOUtils.copyBytes(inputStream, System.out, 4096, false);
    } catch (URISyntaxException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        try {
            hdfs.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        IOUtils.closeStream(inputStream);
    }

这是完整的异常：

java.io.IOException: Failed on local exception: org.apache.hadoop.ipc.RpcException: RPC response exceeds maximum data length; 
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:785)
at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1485)
at org.apache.hadoop.ipc.Client.call(Client.java:1427)
at org.apache.hadoop.ipc.Client.call(Client.java:1337)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
at com.sun.proxy.$Proxy10.getBlockLocations(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getBlockLocations(ClientNamenodeProtocolTranslatorPB.java:255)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:398)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:163)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:155)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:335)
at com.sun.proxy.$Proxy11.getBlockLocations(Unknown Source)
at org.apache.hadoop.hdfs.DFSClient.callGetBlockLocations(DFSClient.java:826)
at org.apache.hadoop.hdfs.DFSClient.getLocatedBlocks(DFSClient.java:815)
at org.apache.hadoop.hdfs.DFSClient.getLocatedBlocks(DFSClient.java:804)
at org.apache.hadoop.hdfs.DFSInputStream.fetchLocatedBlocksAndGetLastBlockLength(DFSInputStream.java:319)
at org.apache.hadoop.hdfs.DFSInputStream.openInfo(DFSInputStream.java:281)
at org.apache.hadoop.hdfs.DFSInputStream.<init>(DFSInputStream.java:270)
at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:1115)
at org.apache.hadoop.hdfs.DistributedFileSystem$4.doCall(DistributedFileSystem.java:325)
at org.apache.hadoop.hdfs.DistributedFileSystem$4.doCall(DistributedFileSystem.java:321)
at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
at org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:333)
at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:786)
at DataUtil.readData(DataUtil.java:29)
at main(Main.java:24)
Caused by: org.apache.hadoop.ipc.RpcException: RPC response exceeds maximum data length
at org.apache.hadoop.ipc.Client$IpcStreams.readResponse(Client.java:1800)
at org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse(Client.java:1155)
at org.apache.hadoop.ipc.Client$Connection.run(Client.java:1052)

Answer 1

检查您的 core-site.xml :

<property>
    <name>fs.default.name</name>
    <value>hdfs://host:port</value>
</property>

此端口可以是 9000 或 8020。 确保您在代码或命令中使用相同的端口

Answer 2

尝试这个解决方案： 将此配置添加到 hdfs-site.xml

<property>
     <name>ipc.maximum.data.length</name>
     <value>134217728</value>
</property>

Answer 3

首先需要检查活动namenode的namenode.log中的真实响应数据长度。 消息必须类似于：

WARN org.apache.hadoop.ipc.Server: Large response size 786010791 for call Call#3

知道响应数据长度后，可以根据实际大小更改参数 ipc.maximum.data.length。

顺便说一句，问题可能出在客户端，就像我的情况一样。因此只需将参数添加到客户端 core-site.xml 或直接添加到命令中即可。 例如：

hadoop distcp -D ipc.maximum.response.length=1073741824 ...