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Sequential Consistency
Sequential consistency is a consistency model used in the domain of concurrent computing (e.g. in distributed shared memory, distributed transactions, etc.). It is the property that "... the result of any execution is the same as if the operations of all the processors were executed in some sequential order, and the operations of each individual processor appear in this sequence in the order specified by its program." That is, the execution order of a program in the same processor (or thread) is the same as the program order, while the execution order of a program on different processors (or threads) is undefined. In an example like this: execution order between A1, B1 and C1 is preserved, that is, A1 runs before B1, and B1 before C1. The same for A2 and B2. But, as execution order between processors is undefined, B2 might run before or after C1 (B2 might physically run before C1, but the effect of B2 might be seen after that of C1, which is the same as "B2 run after C1") Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Consistency Model
In computer science, a consistency model specifies a contract between the programmer and a system, wherein the system guarantees that if the programmer follows the rules for operations on memory, memory will be consistent and the results of reading, writing, or updating memory will be predictable. Consistency models are used in distributed systems like distributed shared memory systems or distributed data stores (such as filesystems, databases, optimistic replication systems or web caching). Consistency is different from coherence, which occurs in systems that are cached or cache-less, and is consistency of data with respect to all processors. Coherence deals with maintaining a global order in which writes to a single location or single variable are seen by all processors. Consistency deals with the ordering of operations to multiple locations with respect to all processors. High level languages, such as C++ and Java, maintain the consistency contract by translating memory o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Computing
Concurrent computing is a form of computing in which several computations are executed '' concurrently''—during overlapping time periods—instead of ''sequentially—''with one completing before the next starts. This is a property of a system—whether a program, computer, or a network—where there is a separate execution point or "thread of control" for each process. A ''concurrent system'' is one where a computation can advance without waiting for all other computations to complete. Concurrent computing is a form of modular programming. In its paradigm an overall computation is factored into subcomputations that may be executed concurrently. Pioneers in the field of concurrent computing include Edsger Dijkstra, Per Brinch Hansen, and C.A.R. Hoare. Introduction The concept of concurrent computing is frequently confused with the related but distinct concept of parallel computing, Pike, Rob (2012-01-11). "Concurrency is not Parallelism". ''Waza conference'', 11 Janu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Shared Memory
In computer science, distributed shared memory (DSM) is a form of memory architecture where physically separated memories can be addressed as a single shared address space. The term "shared" does not mean that there is a single centralized memory, but that the address space is shared—i.e., the same physical address on two processors refers to the same location in memory. Distributed global address space (DGAS), is a similar term for a wide class of software and hardware implementations, in which each node of a cluster has access to shared memory in addition to each node's private (i.e., not shared) memory. Overview A distributed-memory system, often called a multicomputer, consists of multiple independent processing nodes with local memory modules which is connected by a general interconnection network. Software DSM systems can be implemented in an operating system, or as a programming library and can be thought of as extensions of the underlying virtual memory architectur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Transaction
A distributed transaction is a database transaction in which two or more network hosts are involved. Usually, hosts provide transactional resources, while the transaction manager is responsible for creating and managing a global transaction that encompasses all operations against such resources. Distributed transactions, as any other transactions, must have all four ACID (atomicity, consistency, isolation, durability) properties, where atomicity guarantees all-or-nothing outcomes for the unit of work (operations bundle). Open Group, a vendor consortium, proposed the X/Open Distributed Transaction Processing (DTP) Model (X/Open XA), which became a de facto standard for behavior of transaction model components. Databases are common transactional resources and, often, transactions span a couple of such databases. In this case, a distributed transaction can be seen as a database transaction that must be synchronized (or provide ACID properties) among multiple participating databases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leslie Lamport
Leslie B. Lamport (born February 7, 1941 in Brooklyn) is an American computer scientist and mathematician. Lamport is best known for his seminal work in distributed systems, and as the initial developer of the document preparation system LaTeX and the author of its first manual. Lamport was the winner of the 2013 Turing Award for imposing clear, well-defined coherence on the seemingly chaotic behavior of distributed computing systems, in which several autonomous computers communicate with each other by passing messages. He devised important algorithms and developed formal modeling and verification protocols that improve the quality of real distributed systems. These contributions have resulted in improved correctness, performance, and reliability of computer systems. Early life and education Lamport was born into a Jewish family in Brooklyn, New York, the son of Benjamin and Hannah Lamport (née Lasser). His father was an immigrant from Volkovisk in the Russian Empire (now Vawk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sequential Consistency
Sequential consistency is a consistency model used in the domain of concurrent computing (e.g. in distributed shared memory, distributed transactions, etc.). It is the property that "... the result of any execution is the same as if the operations of all the processors were executed in some sequential order, and the operations of each individual processor appear in this sequence in the order specified by its program." That is, the execution order of a program in the same processor (or thread) is the same as the program order, while the execution order of a program on different processors (or threads) is undefined. In an example like this: execution order between A1, B1 and C1 is preserved, that is, A1 runs before B1, and B1 before C1. The same for A2 and B2. But, as execution order between processors is undefined, B2 might run before or after C1 (B2 might physically run before C1, but the effect of B2 might be seen after that of C1, which is the same as "B2 run after C1") Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarita V
Sarita may refer to: Sarah”, meaning “woman of high rank, Princess, essence, speckled”. --> People * Sarita Choudhury (born 1966), British-Indian actress * Sarita Khajuria (1974–2003), British-Indian actress * Sarita Joshi (born 1941), Indian television actress * Sarita Pérez de Tagle (born 1986), Filipina actress * Sarita Schoenebeck, American computer scientist * Laishram Sarita Devi (born 1982), Indian boxer * Sarita, ring name of professional wrestler Sarah Stock (born 1979) Other uses * 796 Sarita, a minor planet * ''Sarita'' (magazine), a Hindi magazine published by Delhi Press Group * ''Sarita'' (play), a 1984 play by Maria Irene Fornes * Sarita, Texas, United States * Sarita Lake, Vancouver Island, British Columbia, Canada * USS ''Sarita'' (AKA-39), an Artemis-class attack cargo ship * a doll in the Manhattan Toy Groovy Girls doll line * a character in the video game '' The Walking Dead: Season Two'' See also *Sarah (other) * Sarai (disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kourosh Gharachorloo
Kourosh ( fa, کوروش، کورش; also spelled as ''Koorosh'' or ''Kurosh'') is a Persian male name common in Iran. Kourosh is composed of ''kouro''- un+ -''sh'' - roprietorial suffix meaning "Lord of the sun". It was the throne name of Cyrus the Great and some other kings of the Achaemenid dynasty, historically translated into English and Latin as "Cyrus". Etymology The name ''Cyrus'' is a Latinized form derived from the Greek Κῦρος, ''Kỹros'', itself from the Old Persian ''Kūruš''. The name and its meaning has been recorded in ancient inscriptions in different languages. The ancient Greek historians Ctesias and Plutarch noted that Cyrus was named from ''Kuros'', the Sun, a concept which has been interpreted as meaning "like the Sun" (Khurvash) by noting its relation to the Persian noun for sun, ''khouro'', while using ''-sh'' as a proprietorial suffix.; Plutarch, ''Artaxerxes'' 1. classics.mit.edu Photius, ''Epitome of Ctesias' Persica'' 5livius.org/ref> This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strict Consistency
In computer science, a consistency model specifies a contract between the programmer and a system, wherein the system guarantees that if the programmer follows the rules for operations on memory, memory will be consistent and the results of reading, writing, or updating memory will be predictable. Consistency models are used in distributed systems like distributed shared memory systems or distributed data stores (such as filesystems, databases, optimistic replication systems or web caching). Consistency is different from coherence, which occurs in systems that are cached or cache-less, and is consistency of data with respect to all processors. Coherence deals with maintaining a global order in which writes to a single location or single variable are seen by all processors. Consistency deals with the ordering of operations to multiple locations with respect to all processors. High level languages, such as C++ and Java, maintain the consistency contract by translating memory opera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Data Structure
In computer science, a concurrent data structure is a particular way of storing and organizing data for access by multiple computing threads (or processes) on a computer. Historically, such data structures were used on uniprocessor machines with operating systems that supported multiple computing threads (or processes). The term concurrency captured the multiplexing/interleaving of the threads' operations on the data by the operating system, even though the processors never issued two operations that accessed the data simultaneously. Today, as multiprocessor computer architectures that provide parallelism become the dominant computing platform (through the proliferation of multi-core processors), the term has come to stand mainly for data structures that can be accessed by multiple threads which may actually access the data simultaneously because they run on different processors that communicate with one another. The concurrent data structure (sometimes also called a ''shar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linearizability
In concurrent programming, an operation (or set of operations) is linearizable if it consists of an ordered list of invocation and response events (event), that may be extended by adding response events such that: # The extended list can be re-expressed as a sequential history (is serializable). # That sequential history is a subset of the original unextended list. Informally, this means that the unmodified list of events is linearizable if and only if its invocations were serializable, but some of the responses of the serial schedule have yet to return. In a concurrent system, processes can access a shared object at the same time. Because multiple processes are accessing a single object, there may arise a situation in which while one process is accessing the object, another process changes its contents. Making a system linearizable is one solution to this problem. In a linearizable system, although operations overlap on a shared object, each operation appears to take place i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serializability
In concurrency control of databases, Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman (1987)''Concurrency Control and Recovery in Database Systems''(free PDF download), Addison Wesley Publishing Company, Gerhard Weikum, Gottfried Vossen (2001)''Transactional Information Systems'' Elsevier, transaction processing (transaction management), and various transactional applications (e.g., transactional memoryMaurice Herlihy and J. Eliot B. Moss. ''Transactional memory: architectural support for lock-free data structures.'' Proceedings of the 20th annual international symposium on Computer architecture (ISCA '93). Volume 21, Issue 2, May 1993. and software transactional memory), both centralized and distributed, a transaction schedule is serializable if its outcome (e.g., the resulting database state) is equal to the outcome of its transactions executed serially, i.e. without overlapping in time. Transactions are normally executed concurrently (they overlap), since this is the mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
