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From "Steven Denny (JIRA)" <j...@apache.org>
Subject [jira] Commented: (NUTCH-721) Fetcher2 Slow
Date Mon, 13 Jul 2009 07:27:15 GMT

    [ https://issues.apache.org/jira/browse/NUTCH-721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12730242#action_12730242
] 

Steven Denny commented on NUTCH-721:
------------------------------------

I've done some testing on this and looked at the number of pages being fed, as this obvioulsy
limits the number of pages you can fetch:

2009-07-10 04:01:35,296 INFO fetcher.Fetcher - Fed 500 urls in 186 secs = 2.7url/s
2009-07-10 04:04:18,343 INFO fetcher.Fetcher - Fed 499 urls in 163 secs = 3.1url/s
2009-07-10 04:06:57,109 INFO fetcher.Fetcher - Fed 498 urls in 158 secs = 3.2url/s
2009-07-10 04:10:38,282 INFO fetcher.Fetcher - Fed 499 urls in 221 secs = 2.3url/s
2009-07-10 04:12:58,371 INFO fetcher.Fetcher - Fed 498 urls in 140 secs = 3.6url/s
2009-07-10 04:16:12,275 INFO fetcher.Fetcher - Fed 499 urls in 193 secs = 2.6url/s
2009-07-10 04:19:20,162 INFO fetcher.Fetcher - Fed 499 urls in 187 secs = 2.7url/s
2009-07-10 04:21:25,846 INFO fetcher.Fetcher - Fed 499 urls in 125 secs = 4.0url/s
2009-07-10 04:24:16,049 INFO fetcher.Fetcher - Fed 495 urls in 170 secs = 2.9url/s
2009-07-10 04:27:01,944 INFO fetcher.Fetcher - Fed 499 urls in 165 secs = 3.0url/s
2009-07-10 04:29:26,247 INFO fetcher.Fetcher - Fed 499 urls in 144 secs = 3.5url/s
2009-07-10 04:32:02,590 INFO fetcher.Fetcher - Fed 499 urls in 156 secs = 3.2url/s
2009-07-10 04:34:49,985 INFO fetcher.Fetcher - Fed 498 urls in 167 secs = 3.0url/s
2009-07-10 04:37:28,367 INFO fetcher.Fetcher - Fed 498 urls in 158 secs = 3.2url/s
2009-07-10 04:40:09,865 INFO fetcher.Fetcher - Fed 499 urls in 161 secs = 3.1url/s
2009-07-10 04:42:55,203 INFO fetcher.Fetcher - Fed 499 urls in 165 secs = 3.0url/s

That test was one a crawldb just initialised with 11,000 urls (unique sites).

However, on the next iteration where I'm feeding urls from non-unique sites, I see 5-7 times
that rate. (My test system is a vm on our network, with nothing special in terms of DNS. Someof
the look ups were taking 5-6 seconds).

> Fetcher2 Slow
> -------------
>
>                 Key: NUTCH-721
>                 URL: https://issues.apache.org/jira/browse/NUTCH-721
>             Project: Nutch
>          Issue Type: Bug
>          Components: fetcher
>    Affects Versions: 1.0.0
>         Environment: Fedora Core r6, Kernel 2.6.22-14,  jdk1.6.0_12
>            Reporter: Roger Dunk
>         Attachments: crawl_generate.tar.gz, nutch-site.xml
>
>
> Fetcher2 fetches far more slowly than Fetcher1.
> Config options:
> fetcher.threads.fetch = 80
> fetcher.threads.per.host = 80
> fetcher.server.delay = 0
> generate.max.per.host = 1
> With a queue size of ~40,000, the result is:
> activeThreads=80, spinWaiting=79, fetchQueues.totalSize=0
> with maybe a download of 1 page per second.
> Runing with -noParse makes little difference.
> CPU load average is around 0.2. With Fetcher1 CPU load is around 2.0 - 3.0
> Hosts already cached by local caching NS appear to download quickly upon a re-fetch,
so possible issue relating to NS lookups, however all things being equal Fetcher1 runs fast
without pre-caching hosts.

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