Sorry, forgot to say, there is an added precondition to causing the bug: The redirection has to be fetched before the page it redirects to... if not, there will be a pre.existing crawl datum with an reasonable refetch-interval.
2009/4/1 George Herlin <ghher...@gmail.com> > Hello, there. > > I believe I may have found a infinite loop in Nutch 0.9. > > It happens when a site has a page that refers to itself through a > redirection. > > The code in Fetcher.run(), around line 200 - sorry, my Fetcher has been a > little modified, line numbers may vary a little - says, for that case: > > output(url, new CrawlDatum(), null, null, CrawlDatum.STATUS_LINKED); > > What that does is, inserts an extra (empty) crawl datum for the new url, > with a re-fetch interval of 0.0. > > However, (see Generator.Selector.map(), particularly lines 144-145), the > non-refetch condition used seems to be last-fetch+refetch-interval>now ... > which is always false if refetch-interval==0.0! > > Now, if there is a new link to the new url in that page, that crawl datum > is re-used, and the whole thing loops indefinitely. > > I've fixed that for myself by changing the quoted line (twice) by: > > output(url, new CrawlDatum(CrawlDatum.STATUS_LINKED, 30f), null, null, > CrawlDatum.STATUS_LINKED); > > and that works (btw the 30F should really be the value of > "db.default.fetch.interval", but I haven't the time right now to work out > the issues, but in reality the default constructor and the appropriate > updater method should, if I am right in analysing the algorithm always > enforce a positive refetch interval. > > Of course, another method could be used to remove this self-reference, but > that couls be complicated, as that may happen through a loop (2 or more > pages etc..., you know what I mean). > > Has that been fixed already, and by what method? > > Best regards > > George Herlin > > > >
