log.trace(this + " sending ping to server. Currently managing lease " +
"for following clients:\n" + sb.toString());
}
Map clientsClone = new ConcurrentHashMap(clients);
Map requestClients = new ConcurrentHashMap();
requestClients.put(ClientHolder.CLIENT_HOLDER_KEY, clientsClone);
InvocationRequest ir =
new InvocationRequest(invokerSessionID, null, "$PING$", requestClients, null, null);
invoker.invoke(ir);