[NUTCH-2354] Upgrade Hadoop dependencies to 2.7.4

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.12
• Fix Version/s: 1.14
• Component/s: injector
• Patch Info: Patch Available
• Flags: Important
• Assignee: Markus Jelsma
• Reporter: Markus Jelsma
• Created: 20/Jan/17 13:23
• Updated: 13/Mar/24 14:50
• Resolved: 15/Dec/17 19:38

Description

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.

Issue Links

• links to: GitHub Pull Request #261