我有一个mapreduce应用程序，它接受HBase源数据并将其mapreduces到另一个HBase表，全部用Java编写。当我使用
运行它时hadoop jar myhbase.jar
以＃{1}}终止 如下：
NullpointerException我正在使用
14/01/31 11:07:02 INFO zookeeper.ClientCnxn: Socket connection established to 127.0.0.1/127.0.0.1:2181, initiating session
14/01/31 11:07:02 INFO zookeeper.ClientCnxn: Session establishment complete on server 127.0.0.1/127.0.0.1:2181, sessionid = 0x143e677d6e30007, negotiated timeout = 180000
14/01/31 11:07:03 INFO mapreduce.TableOutputFormat: Created table instance for hourinfo
14/01/31 11:07:03 INFO mapred.JobClient: Cleaning up the staging area hdfs://192.168.1.149:9000/hadoop_tmp/mapred/staging/root/.staging/job_201401310933_0002
Exception in thread "main" java.lang.NullPointerException
at org.apache.hadoop.net.DNS.reverseDns(DNS.java:72)
at org.apache.hadoop.hbase.mapreduce.TableInputFormatBase.reverseDNS(TableInputFormatBase.java:219)
at org.apache.hadoop.hbase.mapreduce.TableInputFormatBase.getSplits(TableInputFormatBase.java:184)
at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:962)
at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:979)
at org.apache.hadoop.mapred.JobClient.access$600(JobClient.java:174)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:897)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:500)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:530)
at mapreduce.hi.api.hbase.HBaseJobRunner.main(HBaseJobRunner.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
和hbase-0.94.5。我真的陷入了这个错误。请帮助..
答案 0 :(得分：1)
查看堆栈跟踪的顶部：
at org.apache.hadoop.net.DNS.reverseDns(DNS.java:72)
确保您的正向和反向DNS查找与HBase / ZK节点完全匹配。
答案 1 :(得分：-1)
好的，我解决了这个问题。从我得到的例外来看，它来自TableInputFormatBase.getSplits()。当我分析TableInputFormatBase的源代码时，它正在寻找作业配置参数hbase.nameserver.address。当我从我的代码中设置此值时，它可以工作。