question: private void _init ( Configuration conf ) { try { if ( this . id > 0 ) { DefaultListener d = new DefaultListener ( ) ; d . upgrade ( conf , this ) ; } if ( ! X . isEmpty ( listener ) ) { String name = listener ; if ( name != null ) { try { Class < ? > c = Class . forName ( name , true , classLoader ) ; Object o = c . newInstance ( ) ; if ( o instanceof IListener ) { log . info ( "initializing: " + name ) ; IListener l = ( IListener ) o ; l . upgrade ( conf , this ) ; l . onStart ( conf , this ) ; } } catch ( Throwable e ) { log . error ( this . name + ", listener=" + name , e ) ; } } } } catch ( Throwable e ) { log . error ( e . getMessage ( ) , e ) ; } }
target:  invoke the life listener of the module