class type parallelizer =object..end
method ptype : parallelization_typemethod init : unit -> unitmethod start_thread : (par_thread -> unit) ->
       Unix.file_descr list ->
       string -> logger -> par_threadstart_thread f l name logger: Starts a new thread or process and calls
 f thread in that context. The list of file descriptors l is ensured
 to be shared with the main process.
There is no way to check when the thread terminates.
 It is allowed that the par_thread object passed to f is a different
 object as the returned par_thread object.
method create_mem_mutex : unit -> (unit -> unit) * (unit -> unit)let lock, unlock = par#create_mem_locker(): Creates a mutex that
 is sufficient to protect process memory from uncoordinated access.
 The function lock obtains the lock, and unlock releases it.method current_sys_id : [ `Process of int | `Thread of int ]