*/
private AsyncGroupImpl defaultGroup() throws IOException {
synchronized (this) {
if (defaultGroupInstance == null) {
ThreadPoolFactory tpf = getThreadPoolFactory();
ExecutorService executor = tpf.newThreadPool();
defaultGroupInstance = openAsynchronousChannelGroup(executor);
defaultGroupInstance.uncaughtHandler = defaultUncaughtHandler;
defaultUncaughtHandler = null;
}
return defaultGroupInstance;