[
https://issues.apache.org/jira/browse/NUTCH-1922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14294918#comment-14294918
]
Michiel commented on NUTCH-1922:
--------------------------------
Hi,
I applied the patch from NUTCH-1679 (manually, DbUpdateReducer has changed a
bit since then). It fixed the issue: functionality of both batchId and -all is
as expected. Although I am fairly new to Nutch, I think this solution is good
enough for inclusion in a bug fix release.
For a release beyond that, someone with a deeper knowledge of the process needs
to take a look at merging the found inlinks with inlinkedScoreData, just as the
commentary on NUTCH-1679 suggests.
> DbUpdater overwrites fetch status for URLs from previous batches, causes
> repeated re-fetches
> --------------------------------------------------------------------------------------------
>
> Key: NUTCH-1922
> URL: https://issues.apache.org/jira/browse/NUTCH-1922
> Project: Nutch
> Issue Type: Bug
> Affects Versions: 2.3
> Reporter: Gerhard Gossen
>
> When Nutch 2 finds a link to a URL that was crawled in a previous batch, it
> resets the fetch status of that URL to {{unfetched}}. This makes this URL
> available for a re-fetch, even if its crawl interval is not yet over.
> To reproduce, using version 2.3:
> {code}
> # Nutch configuration
> ant runtime
> cd runtime/local
> mkdir seeds
> echo http://www.l3s.de/~gossen/nutch/a.html > seeds/1.txt
> bin/crawl seeds test 2
> {code}
> This uses two files {{a.html}} and {{b.html}} that link to each other.
> In batch 1, Nutch downloads {{a.html}} and discovers the URL of {{b.html}}.
> In batch 2, Nutch downloads {{b.html}} and discovers the link to {{a.html}}.
> This should update the score and link fields of {{a.html}}, but not the fetch
> status. However, when I run {{bin/nutch readdb -crawlId test -url
> http://www.l3s.de/~gossen/nutch/a.html | grep -a status}}, it returns
> {{status: 1 (status_unfetched)}}.
> Expected would be {{status: 2 (status_fetched)}}.
> The reason seems to be that DbUpdateReducer assumes that [links to a URL not
> processed in the same batch always belong to new
> pages|https://github.com/apache/nutch/blob/release-2.3/src/java/org/apache/nutch/crawl/DbUpdateReducer.java#L97-L109].
> Before NUTCH-1556, all pages in the crawl DB were processed by the DBUpdate
> job, but that change skipped all pages with a different batch ID, so I assume
> that this introduced this behavior.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
