Hi, Just a related question: Does.it make a big difference to fetch and parse directly than fetch all first, then parse. I was.under the impression that they yield.to the same end result....
Remi On Wednesday, February 15, 2012, Markus Jelsma <[email protected]> wrote: > >> my questions/doubts are inline >> >> On Tue, Feb 14, 2012 at 4:06 PM, Lewis John Mcgibbney < >> >> [email protected]> wrote: >> > Hi Puneet, >> > >> > On Tue, Feb 14, 2012 at 5:12 AM, Puneet Pandey <[email protected]> >> > >> > wrote: >> > > I have started using nutch recently. >> > > As I understand nutch crawling is a cyclic process >> > > inject->generate->fetch->parse->update >> > >> > Yes this is typically what you would execute. >> > >> > > 1. When does parse start when I use the "crawl" command line. Is it >> > > after all the urls have been fetched in the segment? >> > >> > Depends on what settings you specify in nutch-site.xml, by default >> > parsing is done as a separate process (after fetching) when using the >> > crawl command. >> >> Suppose i submitted 10K urls in a segment for crawl. Does the parsing of >> the content start as soon as the first URL is available (i.e. fetched) or >> the parsing starts only after all 10K have been fetched. For my use case i >> want parsing to start on the urls as soon as they are available w/o waiting >> for fetch on others to complete. > > don't use the crawl command, it has fetchign and parsing as separate jobs. You > need to enable fetcher.parse to parse fetched files immediately. > >> >> > > What if I want to the parse >> > > the content as soon as it has been fetched? >> > >> > Change your settings in nutch-site.xml to override the defaults, then >> > rebuild the project. >> > >> > > 2. Is it possible to run two fetches in parallel? Suppose I generate 2 >> > > segments is it possible to run fetch on seg1 and seg2 in parallel? >> > >> > Yes this is possible, you would set the number of threads in your fetcher >> > to run this task in parallel. >> > >> > I need to crawl 100K urls everyday. I have separate process which >> > produces >> >> the urls for me, but it is a bit time taking process. I do not want to wait >> for all the urls to be generated and then start the nutch crawl. What i >> want is to start the nutch fetch process whenever I have received a batch >> of urls (say 10K) available. Is it possible to inject the batch2 of 10K >> urls while fetch for batch1 is still running? If yes, when will nutch pick >> the next batch for crawl. > > This is only possible when you use the freegen command. Also, i'd not > recommend running concurrent jobs in local mode. > >> >> Also, I do not want to crawl any of the links from the fetched pages. The >> only urls that need to be crawled are the ones generated by my process. How >> do i ensure this. Is there any config setting with which we can disable >> crawl of links present in fetched pages? > > Update the crawldb with additions disabled. > >> >> > > 3. Can I limit the number of urls per host per segment in the generate >> > >> > step >> > >> > > itself? >> > >> > Yes, please check out nutch-default.xml for generator properties, I don't >> > have the settings off my head but this is possible. >> > >> > > Puneet >> > >> > -- >> > *Lewis* >
