[NUTCH-398] map-reduce very slow when crawling on single server

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Cannot Reproduce
• Affects Version/s: 0.8.1
• Fix Version/s: 1.0.0
• Component/s: fetcher

Environment

linux and windows

• Assignee: Andrzej Bialecki
• Reporter: AJ Chen
• Created: 08/Nov/06 00:27
• Updated: 10/Apr/09 12:29
• Resolved: 27/Dec/08 13:48

Description

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.

Issue Links

• is related to: NUTCH-395 Increase fetching speed