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https://issues.apache.org/jira/browse/NUTCH-2474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16284278#comment-16284278
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ASF GitHub Bot commented on NUTCH-2474:
---------------------------------------
sebastian-nagel opened a new pull request #255: NUTCH-2474 CrawlDbReader -stats
fails with ClassCastException
URL: https://github.com/apache/nutch/pull/255
- replace CrawlDbStatCombiner by CrawlDbStatReducer and ensure
that data is properly processed independently whether and
how often combiner is called
- simplify calculation of minimum and maximum
Tested in local mode. Large scale test on multi-billion CrawlDb (distributed
mode) is scheduled. I'll report the results after the weekend.
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> CrawlDbReader -stats fails with ClassCastException
> --------------------------------------------------
>
> Key: NUTCH-2474
> URL: https://issues.apache.org/jira/browse/NUTCH-2474
> Project: Nutch
> Issue Type: Bug
> Components: crawldb
> Affects Versions: 1.14
> Environment: Java 8, distributed mode: Hadoop CDH 5.13.0
> Reporter: Sebastian Nagel
> Priority: Critical
> Fix For: 1.14
>
>
> In distributed mode CrawlDbReader / readdb -stats fails with a
> ClassCastException in the combiner:
> {noformat}
> 17/12/08 04:57:13 INFO mapreduce.Job: Task Id :
> attempt_1512553291624_0022_m_000039_0, Status : FAILED
> Error: java.lang.ClassCastException: org.apache.hadoop.io.FloatWritable
> cannot be cast to org.apache.hadoop.io.LongWritable
> at
> org.apache.nutch.crawl.CrawlDbReader$CrawlDbStatCombiner.reduce(CrawlDbReader.java:296)
> at
> org.apache.nutch.crawl.CrawlDbReader$CrawlDbStatCombiner.reduce(CrawlDbReader.java:222)
> at
> org.apache.hadoop.mapred.Task$OldCombinerRunner.combine(Task.java:1639)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.mergeParts(MapTask.java:1946)
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.flush(MapTask.java:1514)
> at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:466)
> at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343)
> {noformat}
> FloatWritables are used since NUTCH-2470, so that's when this bug was
> introduced.
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