无法创建、上传文件
问题描述
当前hdfs文件结构如下，现通过JavaAPI远程创建目录和文件
创建目录
执行单元测试成功
通过API写文件
发现迟迟没有完成（可能有问题了，因为是虚拟机，延迟不应这么大）
测试不通过
报错为 org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /hdfsapi/test/api.txt could only be replicated to 0 nodes instead of minReplication (=1). There are 1 datanode(s) running and 1 node(s) are excluded in this operation. at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1595) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:3287) at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:677) at org.apache.hadoop.hdfs.server.namenode.AuthorizationProviderProxyClientProtocol.addBlock(AuthorizationProviderProxyClientProtocol.java:213) at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:485) at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java) at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:617) at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1073) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2086) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2082) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1693) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2080)
at org.apache.hadoop.ipc.Client.call(Client.java:1471)
at org.apache.hadoop.ipc.Client.call(Client.java:1408)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:230)
at com.sun.proxy.$Proxy12.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:404)
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:256)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:104)
at com.sun.proxy.$Proxy13.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.locateFollowingBlock(DFSOutputStream.java:1704)
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1500)
at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:668)
Process finished with exit code -1
查看文件目录，发现有该文件，但大小为0，显然是文件流无法写入
解决方法
经过爬贴寻找，发现是因为没有开放端口导致文件流无法写入，经过查找，发现Hadoop相关的端口很多，为了便于学习，直接关闭虚拟机防火墙即可，CentOS7 的命令为sudo systemctl stop firewalld.service
关闭防火墙后重新测试，测试通过
再次查看文件系统，发现文件大小已经不为0，说明文件内容已写入，用hadoop fs -cat /hdfsapi/test/api.txt查看文件内容，发现内容一致，问题解决
