process

The class of a process object. In releases prior to 7.0, this was a structure class. Starting in 7.0, it is a standard CLOS class. It can usefully be subclassed. Each process is represented by an instance of this class (or of an application-defined subclass).

Instances of mp:process have these user-visable slots:

• thread (reader: process-thread): is a lisp thread structure holding low-level information. process-thread (and the no-longer used process-stackgroup) used to be nil until the process was made active. This was not a documented feature, but was used as a test of the process state in some code. Such uses will need to be changed. Use process-active-p.
• property-list (accessor: process-property-list) is a place for application-specific properties.
• priority (accessor: process-priority) Has the user-specified process priority. Default is 0. Higher priority values mean higher priority. In general, the highest priority ready process will be running, although this is a little fuzzy in native-thread models because a foreign call that released the heap may allow parallel execution.
• quantum (accessor: process-quantum) number of seconds this process can hold the lisp heap before it will allow other ready processes a chance to run.
• exit-actions (accessor: process-exit-actions) A list of actions of the form (function . arguments). When the process finishes, either normally or via an unwinding kill, it executes the actions by applying the functions to their argument lists.

The rest of the process data is kept in the thread object; for example, process-name accesses a slot in the thread object.

See multiprocessing.htm.

Copyright (c) 1998-2006, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 7.0. The object described on this page has been modified in the 7.0 release; see the Release Notes.
Created 2005.9.20.