Hi, sounds that it is the cause, but I just tested it again. With server.delay = 1s doesn't result in 1page/s, almost the same speed. confused:( I really didn't try to hammer wikipedia, just want to find a site with enough pages to test.
So with more than 12M pages of wikipedia, I guess it is almost impossible to crawl wikipedia on line. How does google do this? Martin Kuen wrote: > > hi there, > > the property "server.delay" is the delay for one site (e.g. wikipedia). > So, > if you have a delay of 0.5 you'll fetch 2 pages per second. > > In my opinion there is something about the fetcher's code that doesn't > makes > it obey this rule in the very beginning . . . probarbly at start-up 30 > threads start immediatly without caring about this setting, which could > cause a high pages/sec value in the beginning . . . but then the rule is > applied correctly and this averaged-value (pages/sec) becomes corrected in > a > step-by-step manner - however I have no evidence for this assumption. > > If you look around the Fetcher's code (or maybe at the http-plugin - don't > remember) you'll find a config-property called " > protocol.plugin.check.blocking". If you set it to false you'll override > the > "server.delay" property. The result of this action is that you'll start > "hammering" the wikipedia site. > I tried to achieve the same by setting the "server.delay" to 0 . . . > however > . . . things didn't work well (I didn't investigate too much - I found the > " > check.blocking" property, which worked?!). > > Btw. I propose that you should not start (large) crawls on the > wikipedia-sites. The wiki guys don't like it. If you're just running a > test > and fetch a few pages . . . ok . . . but a crawl of 8 hours . . . hmm . .. > not just a few pages, right? > Furthermore a "server.delay" of 0.5 doesn't really appear polite to me . . > . > > Ok, so what? If you're interested in indexing the wikipedia articles, you > can set-up wikipedia on your local computer . . . > http://en.wikipedia.org/wiki/Wikipedia:Database_download > Then you can run your fetch on your local machine or in your intranet and > you'll just be limited by the speed of the machine powering the mediawiki > application. I tried this with the German wikipedia dump and it took a > little bit more than 33 hours (AMD Athlon 2600 dualcore, 2GB RAM, WinXP, > java 1.5, nutch 0.9, ~614.000 articles, ~5.3 pages per second). I didn't > really care about performance, so I think this could be faster. > > > cheers > > > > > > On 8/9/07, purpureleaf <[EMAIL PROTECTED]> wrote: >> >> >> Hi, thanks for your reply >> >> Yes I was fetching from wikipedia only, I do this just for test this >> slowing >> down effect. But not too much I think, 4pages/s, still gets slower and >> slower, forever. So the fetcher is supposed to be slower than 1page/s >> (per >> site) ? >> I watched my bandwith, it used less than 20k/s, way less than my prodiver >> feel easy. >> >> >> >> Dennis Kubes-2 wrote: >> > >> > If this is stalling on only a few fetching tasks check the logs, more >> > than likely it is fetching many pages from a single site (i.e. amazon, >> > wikipedia, cnn) and the politeness settings (which you want to keep) >> are >> > slowing it down. >> > >> > If it is stalling on many task but a single machines check the hardware >> > for the machine. We have seed hard disk speed decrease dramatically >> > right before they are going to die. On linux do something like hdparm >> > -tT /dev/hda where hda is the device to check. Average speeds for Sata >> > should be in the 75MBps range for disk reads and 7000+ range for cached >> > reads. >> > >> > Another thing is you may be maxing your bandwidth and your provider is >> > throttling you? >> > >> > Dennis KUbes >> > >> > purpureleaf wrote: >> >> Hi, I have worked with nutch for sometime. One thing I am always >> curious >> >> is >> >> when crawling, fetcher's speed will get slower and slower, no matter >> what >> >> configuration I use. >> >> My last test get this: ( just one site to make the problem more >> simple) >> >> >> >> OS : winxp >> >> java : 1.6.0.2 >> >> nutch: 0.9 >> >> cpu : AMD 1800 >> >> mem : 1G >> >> network : 3m adsl >> >> >> >> site : wikipedia.org >> >> threads per site :30 >> >> server.delay : 0.5 >> >> >> >> It starts about 6page/s, but reduce to 4 in some minutes, then get >> slower >> >> and slower. I have run it for 8 hours, just 2page/s left, and it was >> till >> >> slowing down. >> >> But if I stop it and start one other, it returns full speed (then >> slows >> >> down >> >> again). I am ok with 2 pages/s for one site, but I do hope it will >> keep >> >> that >> >> speed. >> >> >> >> I found there are some guys in this list has the same problem. But I >> >> can't >> >> find an answer. >> >> If nutch designed to work this way? >> >> >> >> Thanks! >> > >> > >> >> -- >> View this message in context: >> http://www.nabble.com/Fetcher-get-slower-and-slower-in-one-run-of-crawling-tf4241580.html#a12073371 >> Sent from the Nutch - User mailing list archive at Nabble.com. >> >> > > -- View this message in context: http://www.nabble.com/Fetcher-get-slower-and-slower-in-one-run-of-crawling-tf4241580.html#a12076754 Sent from the Nutch - User mailing list archive at Nabble.com.
