Thread: meaning of listen queue

Is the second argument to listen to limit the number of connect requests pending, or the total number of connections? I presume the former, since it certianly does not restrict the later with a LOCAL socket. Why/how could a program ever end up with such a queue, since a socket set to listen seems to "accept" a connection as the request is recieved?

Does this also mean that to truly limit the number of connections, a routine must exist to close them as soon as they are made beyond a certian number, or close the listening socket?

Originally Posted by robwhit

If the requests come in faster than the server can accept() them, then the listen queue fills.

Just wanted to clarify for myself that this is the purpose of accept() and not to perform some possible filtering action (if (incoming==okay) accept), and that the queue is NOT the "maximum number of connections".

I'm guessing this is one way a server gets "flooded" -- the CPU clocks out handling the queue. On second thought, even if the queue is full I imagine it won't take much to just "deny" (is that an action, or a socket status detectable by connect?) and accept one by one.