0
我对HDFS有一个奇怪的问题。虽然得到像访问HDFS集群的所有客户端魅力的existant文件操作工作，它没有一个客户端上：hdfs在特定的客户端节点上失败
工作主持人：
[[email protected]]$ hadoop fs -ls /path/to/file.csv
found 1 items
-rw-r--r-- 3 compute supergroup 1628 2013-12-10 12:22 /path/to/file.csv
[[email protected]]$ hadoop fs -get /path/to/file.csv /tmp/test.csv
[[email protected]]$ cat /tmp/test.csv
48991,24768,2013-12-10 00:00:00,1,0.0001,0.0001
不工作主持人：
[[email protected]]$ hadoop fs -ls /path/to/file.csv
Found 1 items
-rw-r--r-- 3 compute supergroup 1628 2013-12-10 12:22 /path/to/file.csv
[[email protected]]$ hadoop fs -get /path/to/file.csv /tmp/test.csv
get: java.lang.NullPointerException
[[email protected]]$ cat /tmp/test.csv
cat: /tmp/test.csv: No such file or directory
在工作主机上使用java hdfs客户端：
[[email protected]]$ java -jar hadoop_get-1.0-SNAPSHOT-jar-with-dependencies.jar hdfs://my.namenode:port /path/to/file.csv
log4j:WARN No appenders could be found for logger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
48991,24768,2013-12-10 00:00:00,1,0.0001,0.0001
在非工作状态下使用java hdfs客户端主机：
[[email protected]]$ java -jar hadoop_get-1.0-SNAPSHOT-jar-with-dependencies.jar hdfs://my.namenode:port /path/to/file.csv
log4j:WARN No appenders could be found for logger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
org.apache.hadoop.ipc.RemoteException(java.lang.NullPointerException): java.lang.NullPointerException
at org.apache.hadoop.ipc.Client.call(Client.java:1225)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:202)
at com.sun.proxy.$Proxy9.getBlockLocations(Unknown Source)
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:601)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:164)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:83)
at com.sun.proxy.$Proxy9.getBlockLocations(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getBlockLocations(ClientNamenodeProtocolTranslatorPB.java:154)
at org.apache.hadoop.hdfs.DFSClient.callGetBlockLocations(DFSClient.java:957)
at org.apache.hadoop.hdfs.DFSClient.getLocatedBlocks(DFSClient.java:947)
at org.apache.hadoop.hdfs.DFSInputStream.fetchLocatedBlocksAndGetLastBlockLength(DFSInputStream.java:171)
at org.apache.hadoop.hdfs.DFSInputStream.openInfo(DFSInputStream.java:138)
at org.apache.hadoop.hdfs.DFSInputStream.<init>(DFSInputStream.java:131)
at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:1104)
at org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:246)
at org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:79)
at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:711)
at my.namespace.client.Client.main(Client.java:34)
看看[覆盖hadoop log4j.properties]（http://stackoverflow.com/questions/9081625/override-log4j-properties-in-hadoop） –
你看到了什么，user1737246？！？发生了什么！？！？ 我们有同样的问题。 DNS不是一个因素。我们能够从所有系统中写入文件，只有一些人有读取文件的问题。他们可以很好地读取目录，移动文件等。只有读取文件失败，出现java.lang.NullPointerException。 – Admin