QValueSpaceItem and QUnixSocket Issue?

[blackfox]

:(

I encounter a problem that writing to QValueSpaceItem is very slow as if something has blocked the executing. See as the following code.

void QCommDeviceController_Private::bringUp()
{
if (!m_sock)
return;

m_sock->write("UP\r\n");
}

There is no contentChanged signal for a long long ... time. Has anybody met this condition?