问题描述
我有一个mapreduce应用程序，它接收一个HBase源数据并将其映射到另一个HBase表中，所有这些表都是用Java编写的。当我使用
I have a mapreduce app that takes an HBase source data and mapreduces it to another HBase table, all written in Java.When I run it using
hadoop jar myhbase.jar
它以 NullpointerException
如下：
It terminated with a NullpointerExceptionas below:
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)
我正在使用 hbase-0.94.5 和 hadoop-1.0.4 。我真的坚持这个错误。请帮助..
I am using hbase-0.94.5 and hadoop-1.0.4. I am really stuck on this error.Please help..
推荐答案
好的，我解决了这个问题。从异常我得到它源于 TableInputFormatBase.getSplits（）。当我分析 TableInputFormatBase 的源代码时，它是寻找作业配置参数 hbase.nameserver.address 。当我从我的代码中设置此值时，它工作。
Okay I fixed the issue. From the exception I got it originated from TableInputFormatBase.getSplits() .When I analyze source code of TableInputFormatBase, it is looking for a job configuration parameter hbase.nameserver.address . When I set this value from my code, it worked.
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