|
Cooperative Multitasking
Cooperative multitasking, also known as non-preemptive multitasking, is a style of computer multitasking in which the operating system never initiates a context switch from a running process to another process. Instead, in order to run multiple applications concurrently, processes voluntarily yield control periodically or when idle or logically blocked. This type of multitasking is called ''cooperative'' because all programs must cooperate for the scheduling scheme to work. In this scheme, the process scheduler of an operating system is known as a cooperative scheduler whose role is limited to starting the processes and letting them return control back to it voluntarily. Usage Although it is rarely used as the primary scheduling mechanism in modern operating systems, it is widely used in memory-constrained embedded systems and also, in specific applications such as CICS or the JES2 subsystem. Cooperative multitasking was the primary scheduling scheme for 16-bit application ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Multitasking
In computing, multitasking is the concurrent execution of multiple tasks (also known as processes) over a certain period of time. New tasks can interrupt already started ones before they finish, instead of waiting for them to end. As a result, a computer executes segments of multiple tasks in an interleaved manner, while the tasks share common processing resources such as central processing units (CPUs) and main memory. Multitasking automatically interrupts the running program, saving its state (partial results, memory contents and computer register contents) and loading the saved state of another program and transferring control to it. This " context switch" may be initiated at fixed time intervals (pre-emptive multitasking), or the running program may be coded to signal to the supervisory software when it can be interrupted (cooperative multitasking). Multitasking does not require parallel execution of multiple tasks at exactly the same time; instead, it allows more than o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mac OS X V10
Mac or MAC most commonly refers to: * Mac (computer), a family of personal computers made by Apple Inc. * Mackintosh, a raincoat made of rubberized cloth * A variant of the word macaroni, mostly used in the name of the dish mac and cheese * Mac, Gaelic for "son", a prefix to family names often appearing in Gaelic names Mac or MAC may also refer to: Arts, entertainment, and media Fictional entities * Mac (''Green Wing''), a television character * Mac (''It's Always Sunny in Philadelphia''), a television character * Mac Gargan, an enemy of Spider-Man * Mac Foster, a character on ''Foster's Home for Imaginary Friends'' * Angus "Mac" MacGyver, from the television series ''MacGyver'' * Cindy "Mac" Mackenzie, from the TV series ''Veronica Mars'' * Lt. Col. Sarah MacKenzie, from the TV series ''JAG'' * Dr. Terrence McAfferty, from Robert Muchamore's ''CHERUB'' and ''Henderson's Boys'' novel series * "Mac" McAnnally, in ''The Dresden Files'' series * Randle McMurphy, in the mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subroutine
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Functions may be defined within programs, or separately in libraries that can be used by many programs. In different programming languages, a function may be called a routine, subprogram, subroutine, method, or procedure. Technically, these terms all have different definitions, and the nomenclature varies from language to language. The generic umbrella term ''callable unit'' is sometimes used. A function is often coded so that it can be started several times and from several places during one execution of the program, including from other functions, and then branch back (''return'') to the next instruction after the ''call'', once the function's task is done. The idea of a subroutine was initially conceived by John Mauchly during his work on ENIAC, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardware Reset
A hardware reset or hard reset of a computer system is a hardware operation that re-initializes the core hardware components of the system, thus ending all current software operations in the system. This is typically, but not always, followed by booting of the system into firmware that re-initializes the rest of the system, and restarts the operating system. Hardware resets are an essential part of the power-on process, but may also be triggered without power cycling the system by direct user intervention via a physical reset button, watchdog timers, or by software intervention that, as its last action, activates the hardware reset line (e.g, in a fatal error where the computer crashes). User initiated hard resets can be used to reset the device if the software hangs, crashes, or is otherwise unresponsive. However, data may become corrupted if this occurs. Generally, a hard reset is initiated by pressing a dedicated reset button, or holding a combination of buttons on some mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watchdog Timer
A watchdog timer (sometimes called a ''computer operating properly'' or ''COP'' timer, or simply a ''watchdog'') is an electronic or software timer that is used to detect and recover from computer malfunctions. Watchdog timers are widely used in computers to facilitate automatic correction of temporary hardware faults, and to prevent errant or malevolent software from disrupting system operation. During normal operation, the computer regularly restarts the watchdog timer to prevent it from elapsing, or "timing out". If, due to a hardware fault or program error, the computer fails to restart the watchdog, the timer will elapse and generate a timeout signal. The timeout signal is used to initiate corrective actions. The corrective actions typically include placing the computer and associated hardware in a safe state and invoking a computer reboot. Microcontrollers often include an integrated, on-chip watchdog. In other computers the watchdog may reside in a nearby chip that connec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preemption (computing)
In computing, preemption is the act of temporarily interrupting an executing task, with the intention of resuming it at a later time. This interrupt is done by an external scheduler with no assistance or cooperation from the task. This preemptive scheduler usually runs in the most privileged protection ring, meaning that interruption and resuming are considered highly secure actions. Such a change in the currently executing task of a processor is known as context switching. User mode and kernel mode In any given system design, some operations performed by the system may not be preemptable. This usually applies to kernel functions and service interrupts which, if not permitted to run to completion, would tend to produce race conditions resulting in deadlock. Barring the scheduler from preempting tasks while they are processing kernel functions simplifies the kernel design at the expense of system responsiveness. The distinction between user mode and kernel mode, which det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Server (computing)
In computing, a server is a piece of computer hardware or software (computer program) that provides functionality for other programs or devices, called " clients". This architecture is called the client–server model. Servers can provide various functionalities, often called "services", such as sharing data or resources among multiple clients, or performing computation for a client. A single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the same device or may connect over a network to a server on a different device. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers. Client–server systems are usually most frequently implemented by (and often identified with) the request–response model: a client sends a request to the server, which performs some action and sends a response back to the client, typically with a result or acknowledg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hang (computing)
In computing, a hang or freeze occurs when either a process or system ceases to respond to inputs. A typical example is when computer's graphical user interface (such as Microsoft Windows) no longer responds to the user typing on the keyboard or moving the mouse. The term covers a wide range of behaviors in both clients and servers, and is not limited to graphical user interface issues. Hangs have varied causes and symptoms, including software or hardware defects, such as an infinite loop or long-running uninterruptible computation, resource exhaustion ( thrashing), under-performing hardware (throttling), external events such as a slow computer network, misconfiguration, and compatibility problems. The fundamental reason is typically resource exhaustion: resources necessary for some part of the system to run are not available, due to being in use by other processes or simply insufficient. Often the cause is an interaction of multiple factors, making "hang" a loose umbrella ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Busy Wait
In computer science and software engineering, busy-waiting, busy-looping or spinning is a technique in which a process repeatedly checks to see if a condition is true, such as whether keyboard input or a lock is available. Spinning can also be used to generate an arbitrary time delay, a technique that was necessary on systems that lacked a method of waiting a specific length of time. Processor speeds vary greatly from computer to computer, especially as some processors are designed to dynamically adjust speed based on current workload. Consequently, spinning as a time-delay technique can produce unpredictable or even inconsistent results on different systems unless code is included to determine the time a processor takes to execute a "do nothing" loop, or the looping code explicitly checks a real-time clock. In most cases spinning is considered an anti-pattern and should be avoided, as processor time that could be used to execute a different task is instead wasted on useless acti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Python (programming Language)
Python is a high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is dynamically-typed and garbage-collected. It supports multiple programming paradigms, including structured (particularly procedural), object-oriented and functional programming. It is often described as a "batteries included" language due to its comprehensive standard library. Guido van Rossum began working on Python in the late 1980s as a successor to the ABC programming language and first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000 and introduced new features such as list comprehensions, cycle-detecting garbage collection, reference counting, and Unicode support. Python 3.0, released in 2008, was a major revision that is not completely backward-compatible with earlier versions. Python 2 was discontinued with version 2.7.18 in 2020. Python consistently ranks as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JavaScript
JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of Website, websites use JavaScript on the Client (computing), client side for Web page, webpage behavior, often incorporating third-party Library (computing), libraries. All major Web browser, web browsers have a dedicated JavaScript engine to execute the Source code, code on User (computing), users' devices. JavaScript is a High-level programming language, high-level, often Just-in-time compilation, just-in-time compiled language that conforms to the ECMAScript standard. It has dynamic typing, Prototype-based programming, prototype-based object-oriented programming, object-orientation, and first-class functions. It is Programming paradigm, multi-paradigm, supporting Event-driven programming, event-driven, functional programming, functional, and imperative programming, imperative programming paradigm, programmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Await
In computer programming, the async/await pattern is a syntactic feature of many programming languages that allows an Asynchrony (computer programming), asynchronous, non-blocking I/O, non-blocking Subroutine, function to be structured in a way similar to an ordinary synchronous function. It is semantically related to the concept of a coroutine and is often implemented using similar techniques, and is primarily intended to provide opportunities for the program to execute other code while waiting for a long-running, asynchronous task to complete, usually represented by Futures and promises, promises or similar data structures. The feature is found in C Sharp 5.0, C# 5.0, C++, C++20, Python (programming language), Python 3.5, F Sharp (programming language), F#, Hack (programming language), Hack, Julia (programming language), Julia, Dart (programming language), Dart, Kotlin (programming language), Kotlin 1.1, Rust (programming language), Rust 1.39, Nim (programming language), Nim 0.9.4, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
