private HandlerThread getHandlerThread(String threadName) {
        threadName += " handler thread";
        HandlerThread ht = handlerThreads.get(threadName);
        if (ht == null) {
            ht = new HandlerThread(threadName);
            handlerThreads.put(threadName, ht);
            ht.setFatalErrorHandler(fatalErrorHandler);
            dispatch.registerLogHandler(ht);
        }
        return ht;
    }
This class implements the log server itself.  At present there is
no runtime configuration;  the server starts up, binds port 19081
and loads builtin plugins.

@author Bjorn Borud
@author Stig Bakken
logserver/src/main/java/com/yahoo/logserver/Server.java