Why org.apache.zookeeper.ClientCnxnSocketNIO#cleanup will sleep 100ms.

void cleanup() {
    if (sockKey != null) {
        SocketChannel sock = (SocketChannel) sockKey.channel();
        sockKey.cancel();
        try {
            sock.socket().shutdownInput();
        } catch (IOException e) {
            LOG.debug("Ignoring exception during shutdown input", e);
        }
        try {
            sock.socket().shutdownOutput();
        } catch (IOException e) {
            LOG.debug("Ignoring exception during shutdown output", e);
        }
        try {
            sock.socket().close();
        } catch (IOException e) {
            LOG.debug("Ignoring exception during socket close", e);
        }
        try {
            sock.close();
        } catch (IOException e) {
            LOG.debug("Ignoring exception during channel close", e);
        }
    }
    try {
        Thread.sleep(100);
    } catch (InterruptedException e) {
        LOG.debug("SendThread interrupted during sleep, ignoring");
    }
    sockKey = null;
}