[ http://issues.apache.org/jira/browse/NUTCH-136?page=comments#action_12363587 ]
Mike Smith commented on NUTCH-136: ---------------------------------- I have had the same problem. Florent suggested to use "protocol-http" instead of "protocol-httpclient", this fixed the problem on single machine, but I still have the same problem when I have multiple data nodes using NDFS. Commenting line 211 didn't help. Here is my results: Injected URL: 80000 only one machine is datanode: 70000 fecthed pages map tasks: 3 reduce tasks: 3 threads: 250 Injected URL: 80000 3 machines are datanode. All machines are partipated in the fetching by looking at the task tracker logs on three machines: 20000 fetched pages map tasks: 12 reduce tasks: 6 threads: 250 Injected URL : 5000 3 machines are datanode. All machines are partipated in the fetching by looking at the task tracker logs on three machines: 1200 fetched pages map tasks: 12 reduce tasks: 6 threads: 250 Injected URL : 1000 3 machines are datanode. All machines are partipated in the fetching by looking at the task tracker logs on three machines: 240 fetched pages Injected URL : 1000 only one machine is datanode: 800 fecthed pages map tasks: 3 reduce tasks: 3 threads: 250 Thanks, Mike > mapreduce segment generator generates 50 % less than excepted urls > -------------------------------------------------------------------- > > Key: NUTCH-136 > URL: http://issues.apache.org/jira/browse/NUTCH-136 > Project: Nutch > Type: Bug > Versions: 0.8-dev > Reporter: Stefan Groschupf > Priority: Critical > > We notice that segments generated with the map reduce segment generator > contains only 50 % of the expected urls. We had a crawldb with 40 000 urls > and the generate commands only created a 20 000 pages segment. This also > happened with the topN parameter, we everytime got around 50 % of the > expected urls. > I tested the PartitionUrlByHost and it looks like it does its work. However > we fixed the problem by changing two things: > First we set the partition to a normal hashPartitioner. > Second we changed Generator.java line 48: > limit = job.getLong("crawl.topN",Long.MAX_VALUE)/job.getNumReduceTasks(); > to: > limit = job.getLong("crawl.topN",Long.MAX_VALUE); > Now it works as expected. > Has anyone a idea what the real source of this problem can be? > In general this is bug has the effect that all map reduce users fetch only 50 > % of it's urls per iteration. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
