QTcpSocket/QCtpServer signals emmited to late when writing into a file with another thread

I have a program where the main thread is a WebServer through a QTcpServer and another thread writing big data in a file. The server work with the event system, using newConnect and readyRead signal...

When the thread is writing into the file, if i try to request for a page from my web server, the response can take lots of time to come. This problem appears randomly but often (~1/5 request), and all problems disappears when the thread has finished to write the file. I use the server on my local machine, so it's not a network speed problem

I build a simple program (in attachment) that reproduce the problem and i compile Qt to try to find the problem. I think the problem is around the file descriptor poll system in the qt glib implementation (QEventDispatcherGlib).
What i think is maybe, when writing in the binary file fd, the poll notifier system is overloaded and doesn't find time to notify the socket fd.
Maybe this is the default behavior and it's normal, or it's a glib or libc problem, nevertheless i can tell that is not usable like this.

I can specify that before using event system for my program i was using the wait* function, i wasn't having any problem.

To reproduce the problem, see the test program in attachment, compile and run the program, and go immediately in the browser to load a page in the webserver http://localhost:8081/. Type F5, often to increase your chance to reproduce the problem.

I already open a discussion here, but i didn't get any answer: http://qt-project.org/forums/viewthread/22641/