Hi, I am porting a tooling class that I wrote on GST for my SIP and MGCP code to Pharo. This class will create a socket and then fork a RX and TX process. I have some issues with 'stopping' the socket. I have created an example that shows the issue in Pharo 2.0 and Pharo 1.4 with the pharovm (and to have more debug output with a re-compiled one). | s rx | s := Socket newUDP. rx := [ [s waitForData. s halt] on: ConnectionClosed do: [ s halt] ] fork. "Wait for the process to hit the readSemaphore" (Delay forSeconds: 3) wait. s close. My expectation is that I will get the ConnectionClosed signal or at least that >>#waitForData will return once the socket is closed. This is based on reading the comment of >>#waitForData. The Socket>>#waitForData documentation reads like this: "Wait for data to arrive. This method will block until data is available or the socket is closed. If the socket is closed a ConnectionClosed exception will be signaled." I had a look at the socket plugin and the following is happening. First aio is disabled, the state set to ThisEndClosed, then ::close is called and in the above case the result is '0' and the following code will be executed: else if (0 == result) { /* close completed synchronously */ SOCKETSTATE(s)= Unconnected; FPRINTF((stderr, "closeConnection: disconnected\n")); SOCKET(s)= -1; } this means that my 'rx' process will happily wait on the readSemaphore of the Socket and will never be woken up. My question are probably: 1.) Is this the intended behavior for Socket>>#close and Socket>>#waitForData? 2.) How should I terminate my RX process? kind regards holger PS: The issue is probably socket specific and not related to UDP.