anybody knows why the socket got stuck?

Hi, Gurus:

I am using TCL socket command to build client-server application
running on two PCs with Fedora linux, basically it runs fine, but
occasionally I encounter an issue, sometimes the socket will get
stuck, at this moment if I go to the server side and type "netstat -
t", I can see the tcp Recv-Q is not 0, what does this mean? also, if I
close the client side application, then server side will show
close_wait state and Recv-Q still non zero. In my application I am
using puts and gets to send and receive pkts between two applications.
Anybody knows why? thanks in advance.

/zhenwu