我用nutch爬网一些网站。有一次，我决定清除所有爬网结果，然后使用hbase shell从hbase存储中删除“webpage”表。
在那次胡思乱想之后

java.util.NoSuchElementException
at java.util.TreeMap.key(TreeMap.java:1221)
at java.util.TreeMap.firstKey(TreeMap.java:285)
at org.apache.gora.memory.store.MemStore.execute(MemStore.java:125)
at org.apache.gora.query.impl.QueryBase.execute(QueryBase.java:73)
at org.apache.gora.mapreduce.GoraRecordReader.executeQuery(GoraRecordReader.java:68)
at org.apache.gora.mapreduce.GoraRecordReader.nextKeyValue(GoraRecordReader.java:110)
at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:531)
at org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:364)
at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:223)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

“inject”任务可以正常工作，但其他任务都会抛出错误（generate、fetch等）。