Additionally, the "shutDown()" method (that shadows the one in org.apache.nutch.plugin.Plugin) appears never to be called, even if System.runFinalizersOnExit(true) (which is deprecated as dangerous) was previously invoked.
The only way of having my shutdown code executed seems to be to place it in my plugin's finalize() method, AND ensuring that the finalizers be called on exit by placing somewhere in the initialization code the (deprecated) call System.runFinalizersOnExit(true) . Enzo ----- Original Message ----- From: "Enzo Michelangeli" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, June 05, 2007 10:20 AM Subject: Loading mechnism of plugin classes and singleton objects >I have a question about the loading mechanism of plugin classes. I'm >working with a custom URLFilter, and I need a singleton object loaded and >initialized by the first instance of the URLFilter, and shared by other >instances (e.g., instantiated by other threads). I was assuming that the >URLFilter class was being loaded only once even when the filter is used by >multiple threads, so I tried to use a static member variable of my >URLFilter class to hold a reference to the object to be shared: but it >appears that the supposed singleton, actually, isn't, because the method >responsible for its instantiation finds the static field initialized to >null. So: are URLFilter classes loaded multiple times by their classloader >in Nutch? The wiki page at >http://wiki.apache.org/nutch/WhichTechnicalConceptsAreBehindTheNutchPluginSystem > >seems to suggest otherwise: > > Until Nutch runtime, only one instance of such a plugin > class is alive in the Java virtual machine. > > (By the way, what does "Until Nutch runtime" mean here? Before Nutch > runtime, no class whatsoever is supposed to be alive in the JVM, is it?) > > Enzo ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Nutch-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/nutch-general
