Difference between revisions of "Thread"
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[[Category:Nodal Concepts]] | [[Category:Nodal Concepts]] | ||
| + | *See also [[loop]] | ||
= General = | = General = | ||
[[w:thread|Threads of execution]] are a way for a program to split itself into two or more simultaneously (or pseudo-simultaneously) running tasks. Threads and processes differ from one operating system to another, but in general, the way that a thread is created and shares its resources is different from the way a process does. | [[w:thread|Threads of execution]] are a way for a program to split itself into two or more simultaneously (or pseudo-simultaneously) running tasks. Threads and processes differ from one operating system to another, but in general, the way that a thread is created and shares its resources is different from the way a process does. | ||
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In the [[nodal model]], the multithreading time-slicing is achieved by [[w:Time-division multiplexing|time-division multiplexing]] using the [[nodal reduction]] algorithm. [[Loop]]s and threads are formed from [[nodeNEXT|next]] and [[nodePREV|prev]] [[association]]s and a [[focus]] association allows the formation of trees of loops and threads. | In the [[nodal model]], the multithreading time-slicing is achieved by [[w:Time-division multiplexing|time-division multiplexing]] using the [[nodal reduction]] algorithm. [[Loop]]s and threads are formed from [[nodeNEXT|next]] and [[nodePREV|prev]] [[association]]s and a [[focus]] association allows the formation of trees of loops and threads. | ||
| − | A thread is just a loop which ends with a ''next'' association linking to [[root]]. This has the effect of the thread automatically unhooking from its context after completion because any node with a [[focus]] of [[root]] is considered to have no focus. Alternatively a context could update its own [[loop]] content dynamically. | + | A thread is just a loop which ends with a ''next'' association linking to [[root]]. This has the effect of the thread automatically unhooking from its context after completion because any node with a [[focus]] of [[root]] is considered to have no focus because every [[quanta]] sent to root is a new quanta. Alternatively a context could update its own [[loop]] content dynamically. |
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| + | If a thread has static structure, then it can appear in many contexts simaltaneously, it's [[parent]] [[association]] will be dynamically maintained by the [[nodal reduction]] algorithm. | ||
Revision as of 02:17, 11 December 2006
- See also loop
General
Threads of execution are a way for a program to split itself into two or more simultaneously (or pseudo-simultaneously) running tasks. Threads and processes differ from one operating system to another, but in general, the way that a thread is created and shares its resources is different from the way a process does.
Multiple threads can be executed in parallel on many computer systems. This multithreading generally occurs by time slicing, wherein a single processor switches between different threads, in which case the processing is not literally simultaneous, for the single processor is only really doing one thing at a time. This switching can happen so fast as to give the illusion of simultaneity to an end user. For instance, a typical PC today contains only one processor core, but you can run multiple programs at once, such as a word processor alongside an audio playback program; though the user experiences these things as simultaneous, in truth, the processor is quickly switching back and forth between these separate processes. On a multiprocessor or multi-core system, threading can be achieved via multiprocessing, wherein different threads and processes can run literally simultaneously on different processors or cores.
Many modern operating systems directly support both time-sliced and multiprocessor threading with a process scheduler. The operating system kernel allows programmers to manipulate threads via the system call interface. Some implementations are called a kernel thread, whereas a lightweight process is a specific type of kernel thread that shares the same state and information.
Nodal
In the nodal model, the multithreading time-slicing is achieved by time-division multiplexing using the nodal reduction algorithm. Loops and threads are formed from next and prev associations and a focus association allows the formation of trees of loops and threads.
A thread is just a loop which ends with a next association linking to root. This has the effect of the thread automatically unhooking from its context after completion because any node with a focus of root is considered to have no focus because every quanta sent to root is a new quanta. Alternatively a context could update its own loop content dynamically.
If a thread has static structure, then it can appear in many contexts simaltaneously, it's parent association will be dynamically maintained by the nodal reduction algorithm.
