Chain of Responsibility with multithreading and exception handling in java

I have a Rest service call for chain of responsibility, for the better performance we have added multi threading but unable to handle the exception Please find the code sample: Starting with Rest Service method

 @POST
    @Path("/dispatch")
    public Response dispatchEvent(){
     Thread steps = new Thread(new HandlerExecutor());
            steps.start();
    } 

HandlerExecutor.java

 public class HandlerExecutor implements Runnable {
        @Override
        public void run() {
            Handler first = HandlerLocator.getHandler();
            if (first != null) {
                first.process();
            }
        }
    } 

HandlerLocator.java

public class HandlerLocator {
    public static Map<String, List<Handler>> allHandlers = null;        
    public static Handler getHandler() {    
        Handler first = null;           
        List<Handler>> h = new HashMap<String, List<Handler>>();
            List<Handler> list = new ArrayList<Handler>();
            list.add(new ConsoleHandler());
            list.add(new FileHandler());
            list.add(new FinalHandler());
            h.put("1", list);
        List<Handler> clientHandlers = h.get("1");          
        if (clientHandlers != null) {
            int size = clientHandlers.size();
                Handler h1, prev = null;

                for (int i = 0; i < size; i++) {
                    h1 = (Handler) clientHandlers.get(i);

                    if (first == null) {
                        first = h1;
                    } else {
                        prev.setNext(h1);
                    }
                    prev = h1;
                }
        }
        return first;
    }
}

Handler.java

 public interface Handler extends Serializable {
                Handler setNext(Handler next);
                void process();
                }

BasicHandler.java