关于HDFS的租约问题的解决

可以参考这篇文章来了解HDFS租约机制 http://www.cnblogs.com/cssdongl/p/6699919.html
客户端在每次读写HDFS文件的时候获取租约对文件进行读写，文件读取完毕了，然后再释放此租约，文件状态就是关闭的了。

问题

报错信息

Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.GeneratedConstructorAccessor54.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.apache.hadoop.hive.shims.HadoopShimsSecure$CombineFileRecordReader.initNextRecordReader(HadoopShimsSecure.java:257)
	... 18 more
Caused by: org.apache.hadoop.hdfs.CannotObtainBlockLengthException: Cannot obtain block length for LocatedBlock{BP-357078323-172.31.38.88-1691909093222:blk_1091075402_17334736; getBlockSize()=619; corrupt=false; offset=0; locs=[DatanodeInfoWithStorage[172.31.44.193:9866,DS-cb959956-5adb-46b6-a7ba-9720ff4e9428,DISK]]}
	at org.apache.hadoop.hdfs.DFSInputStream.readBlockLength(DFSInputStream.java:364)
	at org.apache.hadoop.hdfs.DFSInputStream.fetchLocatedBlocksAndGetLastBlockLength(DFSInputStream.java:271)
	at org.apache.hadoop.hdfs.DFSInputStream.openInfo(DFSInputStream.java:202)
	at org.apache.hadoop.hdfs.DFSInputStream.<init>(DFSInputStream.java:186)
	at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:1012)
	at org.apache.hadoop.hdfs.DistributedFileSystem$4.doCall(DistributedFileSystem.java:317)
	at org.apache.hadoop.hdfs.DistributedFileSystem$4.doCall(DistributedFileSystem.java:313)
	at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
	at org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:325)
	at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:898)
	at org.apache.hadoop.mapred.LineRecordReader.<init>(LineRecordReader.java:109)
	at org.apache.hadoop.mapred.TextInputFormat.getRecordReader(TextInputFormat.java:67)
	at org.apache.hadoop.hive.ql.io.CombineHiveRecordReader.<init>(CombineHiveRecordReader.java:68)
	... 22 more

解决

恢复租约的方式
首先运行下面的命令检查哪些文件块的租约未被释放

hadoop fsck 具体的文件的分区 -openforwrite

然后执行下面的命令释放租约

hdfs debug recoverLease -path /.......（这里是hdfs上具体的文件块）