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Execution Model
A programming language consists of a grammar/syntax plus an execution model. The execution model specifies the behavior of elements of the language. By applying the execution model, one can derive the behavior of a program that was written in terms of that programming language. For example, when a programmer "reads" code, in their mind, they walk through what each line of code does. In effect they simulate the behavior inside their mind. What the programmer is doing is applying the execution model to the code, which results in the behavior of the code. Each and every programming language has an execution model, which determines the manner in which the units of work (that are indicated by program syntax) are scheduled for execution. Detailed examples of the specification of execution models of a few popular languages include those of Python, the execution model of the Unified Parallel C (UPC) programming language, a discussion of various classes of execution model such as for ...
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Syntax (programming Languages)
In computer science, the syntax of a computer language is the rules that defines the combinations of symbols that are considered to be correctly structured statements or expressions in that language. This applies both to programming languages, where the document represents source code, and to markup languages, where the document represents data. The syntax of a language defines its surface form. Text-based computer languages are based on sequences of characters, while visual programming languages are based on the spatial layout and connections between symbols (which may be textual or graphical). Documents that are syntactically invalid are said to have a syntax error. When designing the syntax of a language, a designer might start by writing down examples of both legal and illegal strings, before trying to figure out the general rules from these examples. Syntax therefore refers to the ''form'' of the code, and is contrasted with semantics – the ''meaning''. In processi ...
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Synchronization Construct
Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or ''in time''. Systems that operate with all parts in synchrony are said to be synchronous or ''in sync''—and those that are not are ''asynchronous''. Today, time synchronization can occur between systems around the world through satellite navigation signals and other time and frequency transfer techniques. Navigation and railways Time-keeping and synchronization of clocks is a critical problem in long-distance ocean navigation. Before radio navigation and satellite-based navigation, navigators required accurate time in conjunction with astronomical observations to determine how far east or west their vessel traveled. The invention of an accurate marine chronometer revolutionized marine navigation. By the end of the 19th century, important ports provided time signals in the form of a signal gun, flag, or dropping time ...
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Executable
In computing, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instructions", as opposed to a data file that must be interpreted ( parsed) by a program to be meaningful. The exact interpretation depends upon the use. "Instructions" is traditionally taken to mean machine code instructions for a physical CPU. In some contexts, a file containing scripting instructions (such as bytecode) may also be considered executable. Generation of executable files Executable files can be hand-coded in machine language, although it is far more convenient to develop software as source code in a high-level language that can be easily understood by humans. In some cases, source code might be specified in assembly language instead, which remains human-readable while being closely associated with machine code instructions. The high-level language is comp ...
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Runtime System
In computer programming, a runtime system or runtime environment is a sub-system that exists both in the computer where a program is created, as well as in the computers where the program is intended to be run. The name comes from the compile time and runtime division from compiled languages, which similarly distinguishes the computer processes involved in the creation of a program (compilation) and its execution in the target machine (the run time). Most programming languages have some form of runtime system that provides an environment in which programs run. This environment may address a number of issues including the management of application memory, how the program accesses variables, mechanisms for passing parameters between procedures, interfacing with the operating system, and otherwise. The compiler makes assumptions depending on the specific runtime system to generate correct code. Typically the runtime system will have some responsibility for setting up and managin ...
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Interpreter (computing)
In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An interpreter generally uses one of the following strategies for program execution: # Parse the source code and perform its behavior directly; # Translate source code into some efficient intermediate representation or object code and immediately execute that; # Explicitly execute stored precompiled bytecode made by a compiler and matched with the interpreter Virtual Machine. Early versions of Lisp programming language and minicomputer and microcomputer BASIC dialects would be examples of the first type. Perl, Raku, Python, MATLAB, and Ruby are examples of the second, while UCSD Pascal is an example of the third type. Source programs are compiled ahead of time and stored as machine independent code, which is then linked at run-time and execu ...
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Compiler
In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program. Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman - Second Edition, 2007 There are many different types of compilers which produce output in different useful forms. A ''cross-compiler'' produces code for a different CPU or operating system than the one on which the cross-compiler itself runs. A ''bootstrap compiler'' is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software include, a program that translates from a low-level language t ...
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Programming Model
A programming model is an execution model coupled to an API or a particular pattern of code. In this style, there are actually two execution models in play: the execution model of the base programming language and the execution model of the programming model. An example is Spark where Java is the base language, and Spark is the programming model. Execution may be based on what appear to be library calls. Other examples include the POSIX Threads library and Hadoop's MapReduce MapReduce is a programming model and an associated implementation for processing and generating big data sets with a parallel, distributed algorithm on a cluster. A MapReduce program is composed of a ''map'' procedure, which performs filtering .... In both cases, the execution model of the programming model is different from that of the base language in which the code is written. For example, the C programming language has no behavior in its execution model for input/output or thread behavior. But ...
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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 work is referred to as a '' thread'', and creation and control over these flows is achieved by making calls to the POSIX Threads API. POSIX Threads is an API defined by the standard ''POSIX.1c, Threads extensions (IEEE Std 1003.1c-1995)''. Implementations of the API are available on many Unix-like POSIX-conformant operating systems such as FreeBSD, NetBSD, OpenBSD, Linux, macOS, Android, Solaris, Redox, and AUTOSAR Adaptive, typically bundled as a library libpthread. DR-DOS and Microsoft Windows implementations also exist: within the SFU/SUA subsystem which provides a native implementation of a number of POSIX APIs, and also within third-party packages such as ''pthreads-w32'', which implements pthreads on top of existing Window ...
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Prentice Hall
Prentice Hall was an American major educational publisher owned by Savvas Learning Company. Prentice Hall publishes print and digital content for the 6–12 and higher-education market, and distributes its technical titles through the Safari Books Online e-reference service. History On October 13, 1913, law professor Charles Gerstenberg and his student Richard Ettinger founded Prentice Hall. Gerstenberg and Ettinger took their mothers' maiden names, Prentice and Hall, to name their new company. Prentice Hall became known as a publisher of trade books by authors such as Norman Vincent Peale; elementary, secondary, and college textbooks; loose-leaf information services; and professional books. Prentice Hall acquired the training provider Deltak in 1979. Prentice Hall was acquired by Gulf+Western in 1984, and became part of that company's publishing division Simon & Schuster. S&S sold several Prentice Hall subsidiaries: Deltak and Resource Systems were sold to National Educatio ...
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Scheduling (computing)
In computing, scheduling is the action of assigning ''resources'' to perform ''tasks''. The ''resources'' may be processors, network links or expansion cards. The ''tasks'' may be threads, processes or data flows. The scheduling activity is carried out by a process called scheduler. Schedulers are often designed so as to keep all computer resources busy (as in load balancing), allow multiple users to share system resources effectively, or to achieve a target quality-of-service. Scheduling is fundamental to computation itself, and an intrinsic part of the execution model of a computer system; the concept of scheduling makes it possible to have computer multitasking with a single central processing unit (CPU). Goals A scheduler may aim at one or more goals, for example: * maximizing '' throughput'' (the total amount of work completed per time unit); * minimizing ''wait time'' (time from work becoming ready until the first point it begins execution); * minimizing '' latenc ...
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C (programming Language)
C (''pronounced like the letter c'') is a General-purpose language, general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems, device drivers, protocol stacks, though decreasingly for application software. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the measuring programming language popularity, most widely used programming languages, with C compilers avail ...
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