How does archive work in os x mail mac os#
How does archive work in os x mail software#

Typically, if multiple processors are available in a multitasking environment, then tasks can be divided among the processors. Multiprocessing is the ability of a computer to use more than one processor simultaneously. Multitasking is the ability to handle several different tasks at once. Multitasking and multiprocessing are related concepts, but it is important to understand the distinctions between them. You should not confuse these threads with the preemptively scheduled tasks created by Multiprocessing Services. For example, the Thread Manager allows you to create cooperatively scheduled threads within a task. In older documentation, Apple has sometimes referred to separate units of execution as threads. Note: The definition of task in this document is analogous to the use of the term thread in some other operating systems such as UNIXВ¬В®.

For example, you can create tasks within an application to process information in the background (such as manipulating an image or retrieving data over the network) while still allowing the user to interact with the application using the user interface.

Multiprocessing Services allows you to create preemptive tasks within an application (or process). An application does so by calling WaitNextEvent, which cedes control of the processor until an event occurs that requires the applicationвЂ™s attention. However, each application must voluntarily yield its processor time in order for another application to gain it. The Process Manager can keep track of the actions of several applications.

How does archive work in os x mail mac os#

The Mac OS 8 operating system implements cooperative multitasking between applications. The teacher could vary the amount of time each child got to look at the book depending on various circumstances (for example, some children may read more slowly and therefore need more time). They would assign the book to each child in turn, making sure that each one got a chance to look at it. Preemptive multitasking would be the case where a teacher (or other supervisor) was in charge of letting the children look at the book. Preemptive multitasking allows an external authority to delegate execution time to the available tasks. In such cases, the other children are deprived. However, if a child is greedy, they may spend an inordinate amount of time looking at the book or refuse to give it up altogether. Each child can theoretically get a chance to look at the book. An example of cooperative multitasking is an unsupervised group of children wanting to look at a book. Cooperative multitasking requires that each task voluntarily give up control so that other tasks can execute. Multitasking may be either cooperative or preemptive. Each such task has its own stack and register set. For example, the system may execute multiple applications, and each application may have independently executing tasks within it.

How does archive work in os x mail software#

On a computer, the system software can handle multiple tasks, which may be applications or even smaller units of execution. In programming, a task is simply an independent execution path. Not everything may be happening simultaneously, but you are jumping back and forth, devoting your attention to each task as necessary. For example, you may be working on a project, eating lunch, and talking to a colleague at the same time. Multitasking is essentially the ability to do many things concurrently.

For information about actually using the Multiprocessing Services API in your application, see Using Multiprocessing Services. Note that this chapter covers mostly concepts rather than implementation or programming details. You should read this chapter if you are not familiar with multitasking or multiprocessing concepts. This chapter describes the basic concepts underlying multitasking and how Multiprocessing Services uses them on Macintosh computers. To learn about multiprocessing on OS X, see Concurrency Programming Guide to learn about POSIX thread routines, see pthread. In apps that run in OS X v10.8 and later, you should use Grand Central Dispatch or POSIX threads to support multitasking. In earlier versions of OS X, Multiprocessing Services allowed legacy apps to support multitasking. The Multiprocessing Services API is deprecated in OS X v10.8.