我们的应用程序使用mongo-hadoop saveAsNewAPIHadoopFile（）方法写入Mongo。它适用于数天，但在某些时候，它达到用作临时输出缓冲区的HDFS文件夹的项目/名称配额限制。这导致MongoRecordWriter类中的“无法打开用于缓冲Mongo输出的临时文件”异常（请参阅下面的堆栈跟踪）并阻止从应用程序进一步写入MongoDB。
在做了一些挖掘之后，我们注意到mongo-hadoop中MongoOutputCommitter类的 cleanupResources（final TaskAttemptContext taskContext）方法删除了为输出任务创建的临时文件，但没有删除包含每个临时文件的文件夹我们还没有找到任何设置/配置选项来控制该行为。我们可以增加该HDFS文件夹的名称配额，但这可能会对HDFS产生性能影响并且无法解决任何问题。我们可以有一个nohup维护工作，但这是一个额外的人工制品，我们将其视为一种解决方法。
java.lang.RuntimeException: Could not open temporary file for buffering Mongo output
at com.mongodb.hadoop.output.MongoRecordWriter.<init>(MongoRecordWriter.java:78)
at com.mongodb.hadoop.MongoOutputFormat.getRecordWriter(MongoOutputFormat.java:46)
...
org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.protocol.FSLimitException$MaxDirectoryItemsExceededException): The directory item limit of /user/ec2-user/tmp is exceeded: limit=1048576 items=1048576
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.verifyMaxDirItems(FSDirectory.java:2021)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.addChild(FSDirectory.java:2072)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.unprotectedMkdir(FSDirectory.java:1841)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsRecursively(FSNamesystem.java:4348)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:2748)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInt(FSNamesystem.java:2632)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFile(FSNamesystem.java:2519)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.create(NameNodeRpcServer.java:566)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.create(ClientNamenodeProtocolServerSideTranslatorPB.java:394)
at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:619)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:962)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2039)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2035)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1635)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2033)
at org.apache.hadoop.ipc.Client.call(Client.java:1471)
at org.apache.hadoop.ipc.Client.call(Client.java:1402)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
at com.sun.proxy.$Proxy21.create(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.create(ClientNamenodeProtocolTranslatorPB.java:295)
at sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
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:187)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy22.create(Unknown Source)
at org.apache.hadoop.hdfs.DFSOutputStream.newStreamForCreate(DFSOutputStream.java:1725)
at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1669)
at org.apache.hadoop.hdfs.DFSClient.create(DFSClient.java:1594)
at org.apache.hadoop.hdfs.DistributedFileSystem$6.doCall(DistributedFileSystem.java:397)
at org.apache.hadoop.hdfs.DistributedFileSystem$6.doCall(DistributedFileSystem.java:393)
at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:393)
at org.apache.hadoop.hdfs.DistributedFileSystem.create(DistributedFileSystem.java:337)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:914)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:895)
at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:792)
at com.mongodb.hadoop.output.MongoRecordWriter.<init>(MongoRecordWriter.java:75)
... 9 more