map-reduce very slow when crawling on single server
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Key: NUTCH-398
URL: http://issues.apache.org/jira/browse/NUTCH-398
Project: Nutch
Issue Type: Bug
Components: fetcher
Affects Versions: 0.8.1
Environment: linux and windows
Reporter: AJ Chen
This seems a bug and so I create a ticket here. I'm using nutch 0.9-dev to
crawl web on one linux server. With default hadoop
configuration (local file system, no distributed crawling), the Generator and
Fetcher spend unproportional amount of time on map-reduce opearations. For
example:
2006-11-01 20:32:44,074 INFO crawl.Generator - Generator: segment:
crawl/segments/20061101203244
... (doing map and reduce for 2 hours )
2006-11-01 22:28:11,102 INFO fetcher.Fetcher - Fetcher: segment:
crawl/segments/20061101203244
... (fetching 12 hours )
2006-11-02 11:15:10,590 INFO mapred.LocalJobRunner - 175383 pages, 16583
errors, 3.8 pages/s, 687 kb/s,
2006-11-02 11:17:24,039 INFO mapred.LocalJobRunner - reduce > sort
... (but doing reduce>sort and reduce>duce for 8 hours )
2006-11-02 19:13:38,882 INFO crawl.CrawlDb - CrawlDb update: segment:
crawl/segments/20061101203244
Since it's crawling on a single machine, such slow map-reduce opearation is not
expected.
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