Each process object has a state associated with it; this depends on the status of the subprocess currently running on the process object (or not as the case may be).
The possible states are,
This state means that the subprocess using this process object is currently running, i.e. it hasn’t been stopped.
Means that the subprocess has been temporarily suspended from running.
This means that the process object is free to have a new subprocess created on it.
Predicates exist which test whether a given process object is in one of these states.
Returns true when process-object is in the running state.
Returns true when process-object is in the stopped state.
Returns true when process-object is not in the unused state.
The following two functions are used to stop and then subsequently continue a process running.
This function suspends execution of the subprocess running on the process object process-object.
If whole-group is true all subprocesses in the process group of process-object are stopped.
Use this function to continue a subprocess executing after it has been
stopped (by the
If whole-group is true all subprocesses in the process group of process-object are continued.
The state change function component of a process object defines a function which will be called each time the state of the process object changes. If your program needs to be informed when an asynchronous process terminates this function is the way to do it.
Returns the value of the state change function component of the process object process.
Sets the value of the state change function component of the process object process to the function function, then returns function.