java 输入流关闭顺序_JAVA的节点流和处理流以及流的关闭顺序
今天在編寫hadoop程序的時候,用到了流的處理。關閉流的時候出現了問題:
代碼:
1 FSDataInputStream fsin = fs.open(new Path(filein));
2 FSDataOutputStream fsout = fs.append(new Path(fileout));
3 BufferedReader br = new BufferedReader(new InputStreamReader(fsin));
4 BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(fsout));
5 ...
6 br.close();
7 fsin.close();
8 bw.close();
9 fsout.close();
異常:
1 [root@bigdata004 bigdata]# ./bigdataTimer.sh
2 INFO [main] com.sinosoft.bigdata.BigDataTimer.main(227) | -----Timer begin-----
3 INFO [main] com.sinosoft.bigdata.BigDataInit.(70) | bigdata init ...
4 WARN [main] org.apache.hadoop.util.NativeCodeLoader.(62) | Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
5 INFO [main] com.sinosoft.bigdata.BigDataTimer.mergeFile(66) | Finished appending file.
6 INFO [main] com.sinosoft.bigdata.BigDataTimer.mergeFile(68) | deleted the input data path.
7 INFO [main] com.sinosoft.bigdata.BigDataTimer.mergeFile(70) | create the input data path.
8 ERROR [main] org.apache.hadoop.hdfs.DFSClient.closeAllFilesBeingWritten(776) | Failed to close file /user/root/dayfileInput/dayfileIn
9 org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.server.namenode.LeaseExpiredException): No lease on /user/root/dayfileInput/dayfileIn: File does not exist. Holder DFSClient_NONMAPREDUCE_-221972347_1 does not have any open files.
原因:關閉處理流br.close();之后,緊接著關閉了與之相關的fsin.close();的節點流。事實上,br.close();會調用fsin.close();?因此重復關閉了2次fsin.close();最后拋出了異常。
回顧了一下流的知識:
按照流是否直接與特定的地方(如磁盤、內存、設備等)相連,分為節點流和處理流兩類。
總結
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