question about ObjectCache

[Xiaolong Yang]

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 ?

       Appreciate your time and help.