Hi Markus, after having once faced failing jobs due to dependency issues, I started to compile the Nutch.job with the same Hadoop version of the cluster. That's little extra time to change the ivy.xml and rarely resolve a conflicting dependency, but to fix broken data in the cluster costs you much more.
> Reference issue: https://issues.apache.org/jira/browse/NUTCH-2354 What about the opposite, running Nutch.job compiled with 2.7.3 on a 2.7.2 Hadoop? Nothing against upgrading, but in doubt it would be good to know. Thanks, Sebastian On 01/20/2017 02:23 PM, Markus Jelsma wrote: > Hello, > > This wednesday we experienced trouble running the 1.12 injector on Hadoop > 2.7.3. We operated 2.7.2 before and we had no trouble running a job. > > 2017-01-18 15:36:53,005 FATAL [main] org.apache.hadoop.mapred.YarnChild: > Error running child : java.lang.IncompatibleClassChangeError: Found interface > org.apache.hadoop.mapreduce.Counter, but class was expected > at org.apache.nutch.crawl.Injector$InjectMapper.map(Injector.java:216) > at org.apache.nutch.crawl.Injector$InjectMapper.map(Injector.java:100) > at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146) > at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787) > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341) > at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:164) > at java.security.AccessController.doPrivileged(Native Method) > at javax.security.auth.Subject.doAs(Subject.java:422) > at > org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1698) > at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158) > Exception in thread "main" java.lang.IncompatibleClassChangeError: Found > interface org.apache.hadoop.mapreduce.Counter, but class was expected > at org.apache.nutch.crawl.Injector.inject(Injector.java:383) > at org.apache.nutch.crawl.Injector.run(Injector.java:467) > at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) > at org.apache.nutch.crawl.Injector.main(Injector.java:441) > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > at > sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:498) > at org.apache.hadoop.util.RunJar.run(RunJar.java:221) > at org.apache.hadoop.util.RunJar.main(RunJar.java:136) > > Our processes retried injecting for a few minutes until we manually shut it > down. Meanwhile on HDFS, our CrawlDB was gone, thanks for snapshots and/or > backups we could restore it, so enable those if you haven't done so yet. > > These freak Hadoop errors can be notoriously difficult to debug but it seems > we are in luck, recompile Nutch with Hadoop 2.7.3 instead 2.4.0. You are also > in luck if your job file uses the old org.hadoop.mapred.* API, only jobs > using the org.hadoop.mapreduce.* API seem to fail. > > Reference issue: https://issues.apache.org/jira/browse/NUTCH-2354 > > Regards, > Markus >
