Hi,Andrzej
Thank you for your detail answers.I have understood it uses.[?]
2012/4/10 Andrzej Bialecki a...@getopt.org
On 10/04/2012 05:00, Xiaolong Yang wrote:
Hi，all
I'm reading source code of nutch and I have some puzzled about the
ObjectCache.java in package org.apache.nutch.util.I just find it may be
little benefit to use it in urlnormalizers and urlfiters.I also have
read some discuss about cache in Nutch-169 and Nutch-501.But I can't
understand it.
Can anyone tell me where ObjectCache be used and get a good benefit in
nutch ?
ObjectCache is designed to cache ready-to-use instances of Nutch plugins.
The process of finding, instantiating and initializing plugins is
inefficient, because it involves parsing plugin descriptors, initializing
plugins, collecting the ones that implement correct extension points, etc.
It would kill performance if this process were invoked each time you want
to run all plugins of a given type (e.g. URLNormalizer-s). The facade
URLNormalizers/URLFilters and others make sure that plugin instances of a
given type are initialized once per lifetime of a JVM, and then they are
cached in ObjectCache, so that next time you want to use them they can be
retrieved from a cache, instead of going again through the process of
parsing/instantiating/**initializing.
--
Best regards,
Andrzej Bialecki
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