How do I kill a process that is dead but listening?

I'm developing an app that listens on port 3000. Apparently there's an instance of it still listening to the port because whenever I start it, it can't create a listener (C#, TcpListener, but that's irrelevant) because the port is already taken.

Now, the app doesn't exist in the Task Manager, so I tried to find its PID and kill it, which led to this interesting result:

C:\Users\username>netstat -o -n -a | findstr 0.0:3000
   TCP    0.0.0.0:3000           0.0.0.0:0              LISTENING       3116

C:\Users\username>taskkill /F /PID 3116
ERROR: The process "3116" not found.

I haven't seen this behaviour before and figured it was interesting enough to see if anyone has a solution.

UPDATE: I started up Process Explorer and did a search for 3000 and found this:

<Non-existent Process>(3000): 5552

I right clicked on it and chose "Close Handle". It's no longer in Process Explorer, but still shows up in netstat and still stops the app from starting the listener.

UPDATE 2: Found TCPView for Windows which show the process as "<non-existent>". Like with CurrPorts, nothing happens when I try to close the connection in this tool.

Solution 1:

To avoid endless waits on the socket, your program should use the setsockopt function with the SO_REUSEADDR and SO_RCVTIMEO parameters :

SO_REUSEADDR : Allows the socket to be bound to an address that is already in use.
SO_RCVTIMEO : Sets the timeout, in milliseconds, for blocking receive calls. 

Solution 2:

We had the same problem and used Process Explorer from Microsoft Sysinternals to look up the process ID that no longer existed.

It turns out that the process was referenced by several DrWatson processes. Killing those processes released the port. DrWatson is used to send memory dumps to Microsoft and this was taking several hours because the process that crashed held several tens of GBs of memory at the time.