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Posted to dev@nutch.apache.org by "Sebastian Nagel (JIRA)" <ji...@apache.org> on 2017/11/06 15:06:00 UTC
[jira] [Commented] (NUTCH-2420) Bug in variable generate.max.count
and fetcher.server.delay
[ https://issues.apache.org/jira/browse/NUTCH-2420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16240416#comment-16240416 ]
Sebastian Nagel commented on NUTCH-2420:
----------------------------------------
That's really ugly! It will work in local mode or on a small cluster with not too many hosts, but on a larger cluster a HostDb with many partitions and millions of hosts, it will slow down of Generator significantly. The correct solution would be to use <host,score> pairs as keys in the Selector job, with a partitioner and secondary sorting so that all keys with same host end up in the same call of the reducer. If values can also hold a HostDb entry and the sort comparator guarantees that the HostDb entry (entries if partitioned by domain or IP) comes in front of all CrawlDb entries. But that would be a substantial improvement...
+1 to commit this fix and to open a new one to speed up the merging of HostDb entries
> Bug in variable generate.max.count and fetcher.server.delay
> -----------------------------------------------------------
>
> Key: NUTCH-2420
> URL: https://issues.apache.org/jira/browse/NUTCH-2420
> Project: Nutch
> Issue Type: Bug
> Components: generator
> Reporter: Markus Jelsma
> Assignee: Markus Jelsma
> Fix For: 1.14
>
> Attachments: NUTCH-2420.patch
>
>
> Feature added by NUTCH-2368 does not work for multiple hosts. Once a HostDatum has been read by getHostDatum(), the next host cannot be read. Apparantly i need to open and close the SequenceFile.Readers for every HostDatum it needs. Reader has no reset() method or whatsoever.
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