[英]Nullpointer exception in HBase MapReduce
我有一個mapreduce應用程序,該應用程序接收一個HBase源數據並將其映射到另一個用Java編寫的HBase表中。
hadoop jar myhbase.jar
它以NullpointerException
終止,如下所示:
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
。 我確實對這個錯誤感到困惑。請提供幫助。
查看堆棧跟蹤的頂部:
at org.apache.hadoop.net.DNS.reverseDns(DNS.java:72)
確保您的正向和反向DNS查找在您的HBase / ZK節點上完全匹配。
好吧,我解決了這個問題。 從異常中我得到它源自TableInputFormatBase.getSplits()
。當我分析TableInputFormatBase
源代碼時,它正在尋找作業配置參數hbase.nameserver.address
。 當我從代碼中設置此值時,它就起作用了。
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