Hi,
This was mentioned before: there are many places in Nutch that rely on
static initializers. This is so-so or sometimes plainly bad, depending
on a situation.
I'm facing a problem now with URLFilters. I need to run several fetchers
inside a single VM, with different parameters such as different url
patterns (which is handled by URLFilters). But even if I specify
different NutchConf-s to each fetcher, the list of implementations and
the instances of URLFilter[] in URLFilters are initialized only once,
and this happens from the default configuration obtained through a call
to static NutchConf.get().
I would like to change it somehow, but I'm not sure how... One way to
solve this would be to instantiate the plugins based on a concrete
NutchConf instance, like this:
URLFilters:
private URLFilters(NutchConf) {
// initialize plugins based on this instance of NutchConf
}
public static URLFilters get(NutchConf conf) {
URLFilters res = (URLFilters)conf.get("urlfilters.key");
if (res == null) {
res = new URLFilters(conf);
conf.put("urlfilters.key", res);
}
return res;
}
In case you are running with a single NutchConf per JVM it doesn't change
anything. In case you want to run several different configs in a single JVM
this approach provides the solution. We could follow this strategy for other
plugin registry facades. Comments?
--
Best regards,
Andrzej Bialecki <><
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