globally there are:
  an id-list of processes
  an id-list of threads
  a queue of paused threads
  a single running thread

a paused thread is a thread that can run, but isn't.
a thread that is not running and is not paused is in a blocking syscall.

each process has:
  a process id
  a list of threads
  a list of open file streams
  a list of open socket stream ends
  a list of running socket listeners
  a list of environment variables (pairs of strings)

a thread has:
  an owning process
  optionally:
    a stream end it is waiting to read from
    a socket listener it is waiting to accept a connection from
    a socket listener it is waiting to connect to
  if not running:
    saved cpu state

a socket has:
  two queues

an open socket stream end has:
  a list of threads waiting to read from it
  the socket
  its input queue
  its output queue
  if the other side is open:
    the other process
    the other stream end

a running socket listener has:
  a list of threads waiting to accept a connection from it
  a list of threads waiting to connect to it
