Hi - this very long standing problem has been fixed in a Hadoop more recent than you are using now. Upgrade to 2.7.3 or 2.8.0 if that's out some day.
Markus -----Original message----- > From:Michael Coffey <[email protected]> > Sent: Saturday 4th March 2017 3:49 > To: User <[email protected]> > Subject: readdb to dump a specific url > > I want to find out what the crawldb knows about some specific urls. According > to the nutch wiki, I should use nutch readdb with the -url option. But when I > do a command like the following, I get nasty "can't find class" exceptions. > > > $NUTCH_HOME/runtime/deploy/bin/nutch readdb /crawls/popular/data/crawldb -url > http://fabulous.com/ > > The error message isException in thread "main" java.io.IOException: can't > find class: org.apache.nutch.protocol.ProtocolStatus because > org.apache.nutch.protocol.ProtocolStatus > at > org.apache.hadoop.io.AbstractMapWritable.readFields(AbstractMapWritable.java:212) > at org.apache.hadoop.io.MapWritable.readFields(MapWritable.java:167) > at org.apache.nutch.crawl.CrawlDatum.readFields(CrawlDatum.java:317) > at > org.apache.hadoop.io.SequenceFile$Reader.getCurrentValue(SequenceFile.java:2256) > at org.apache.hadoop.io.MapFile$Reader.get(MapFile.java:680) > at > org.apache.hadoop.mapred.MapFileOutputFormat.getEntry(MapFileOutputFormat.java:99) > at org.apache.nutch.crawl.CrawlDbReader.get(CrawlDbReader.java:465) > at > org.apache.nutch.crawl.CrawlDbReader.readUrl(CrawlDbReader.java:472) > at org.apache.nutch.crawl.CrawlDbReader.run(CrawlDbReader.java:717) > at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) > at org.apache.nutch.crawl.CrawlDbReader.main(CrawlDbReader.java:736) > 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:606) > at org.apache.hadoop.util.RunJar.run(RunJar.java:221) > at org.apache.hadoop.util.RunJar.main(RunJar.java:136) > > > > The above message occurs for any url that is actually in the crawldb. If I > specify a url that does not exist, I get a more understandable message. Also, > nutch readdb -stats works reliably. > How can we make this work? >
