Unix.fork to create new threads.
After forking the child process is initialized by
By default, all file descriptors are closed that are not explicitly
shared with the parent process. This can be wrong for some kind
of applications. By setting
keep_fd_open another behavior can
be demanded: The descriptors are kept open except those that need
to be closed.
When the controller wants to shut down the process, it notifies
the process, and waits
terminate_tmo seconds until the process
terminates. If this timeout expires, the process is killed. Defaults
to 60. A negative value disables this function.