In computing, Multiprocessing Services is a component of the

Classic Mac OS Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Macintosh family of personal computers by Apple Computer from 1984 to 2001, starting with System 1 and ending with Mac OS 9. Th ...

and the retired

Carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

API allowing programs to perform work across multiple preemptively scheduled threads of execution.

Release history

Multiprocessing Services was introduced in 1996 with the release of System 7.5.3. Multiprocessing Services 2.0, introduced in

Mac OS 8.6 Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It includes the largest overhaul of the classic Mac OS experience since the release of System 7, approximately six years before. It places a greater emphasis on ...

, is a backwards-compatible major release that increases the level of integration preemptive tasks have with the rest of the system. Multiprocessing Services 2.1, introduced in

Mac OS 9 Mac OS 9 is the ninth major release of Apple's classic Mac OS operating system which was succeeded by Mac OS X (renamed to OS X in 2011 and macOS in 2016) in 2001. Introduced on October 23, 1999, it was promoted by Apple as "The Best Internet ...

, adds support for devices with more than 1 GB of RAM.

In the Classic Mac OS

In the Classic Mac OS, Multiprocessing Services is not the only threading mechanism; cooperatively scheduled threads can be created with the Thread Manager. While applications using Multiprocessing Services have their threads preemptively scheduled, the application as a whole is still cooperatively scheduled with other running applications. Non-Multiprocessing Services tasks remain scheduled on a single processor, and tasks using the

Macintosh Toolbox The Macintosh Toolbox implements many of the high-level features of the Classic Mac OS, including a set of application programming interfaces for software development on the platform. The Toolbox consists of a number of "managers," software compone ...

cannot be preemptively scheduled. When a process uses Multiprocessing Services, in addition to the preemptive tasks it creates, an additional task exists, deth, which waits for other tasks created by the process to terminate and cleans up their resources when they do.

In macOS

In macOS, Multiprocessing Services is implemented using

POSIX threads POSIX Threads, commonly known as pthreads, is an execution model that exists independently from a language, as well as a parallel execution model. It allows a program to control multiple different flows of work that overlap in time. Each flow of ...

. Applications using Multiprocessing Services are preemptively scheduled with other tasks running on the system. In

OS X 10.8 OS X Mountain Lion (version 10.8) is the ninth software versioning, major release of macOS, Apple Inc.'s desktop and Server (computing), server operating system for Macintosh computers. OS X Mountain Lion was released on July 25, 2012, for purch ...

, Multiprocessing Services was deprecated with the rest of Carbon, with

Grand Central Dispatch Grand Central Dispatch (GCD or libdispatch), is a technology developed by Apple Inc. to optimize application support for systems with multi-core processors and other symmetric multiprocessing systems. It is an implementation of task parallelis ...

suggested as a replacement. In macOS 10.15, support for Multiprocessing Services ended with the removal of 32-bit application support, which included all Carbon applications.

References

{{Classic Mac OS Classic Mac OS