Category: Concurrency control

Conservative two-phase locking
In computer science, conservative two-phase locking (C2PL) is a locking method used in DBMS and relational databases. Conservative 2PL prevents deadlocks. The difference between 2PL and C2PL is that C
Lock convoy
In computer science, a lock convoy is a performance problem that can occur when using locks for concurrency control in a multithreaded application. A lock convoy occurs when multiple threads of equal
Distributed concurrency control
Distributed concurrency control is the concurrency control of a system distributed over a computer network . In database systems and transaction processing (transaction management) distributed concurr
Priority inversion
In computer science, priority inversion is a scenario in scheduling in which a high priority task is indirectly superseded by a lower priority task effectively inverting the assigned priorities of the
Busy waiting
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 o
Lock (computer science)
In computer science, a lock or mutex (from mutual exclusion) is a synchronization primitive: a mechanism that enforces limits on access to a resource when there are many threads of execution. A lock i
Safe semantics
Safe semantics is a computer hardware consistency model. It describes one type of guarantee that a data register provides when it is shared by several processors in a parallel computer or in a network
Non-blocking algorithm
In computer science, an algorithm is called non-blocking if failure or suspension of any thread cannot cause failure or suspension of another thread; for some operations, these algorithms provide a us
Test and test-and-set
In computer science, the test-and-set CPU instruction is used to implement mutual exclusion in multiprocessor environments. Although a correct lock can be implemented with test-and-set, it can lead to
Commitment ordering
Commitment ordering (CO) is a class of interoperable serializability techniques in concurrency control of databases, transaction processing, and related applications. It allows optimistic (non-blockin
Software lockout
In multiprocessor computer systems, software lockout is the issue of performance degradation due to the idle wait times spent by the CPUs in kernel-level critical sections. Software lockout is the maj
In computer science E-LOTOS (Enhanced LOTOS) is a formal specification language designed between 1993 and 1999, and standardized by ISO in 2001. E-LOTOS was initially intended to be a revision of the
In computer science, compare-and-swap (CAS) is an atomic instruction used in multithreading to achieve synchronization. It compares the contents of a memory location with a given value and, only if th
In computer science, ACID (atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other
In computer science, the fetch-and-add CPU instruction (FAA) atomically increments the contents of a memory location by a specified value. That is, fetch-and-add performs the operation increment the v
In computing, a futex (short for "fast userspace mutex") is a kernel system call that programmers can use to implement basic locking, or as a building block for higher-level locking abstractions such
Path expression
In query languages, path expressions identify an object by describing how to navigate to itin some graph (possibly implicit) of objects. For example, the path expression p.Manager.Home.City mig
Priority ceiling protocol
In real-time computing, the priority ceiling protocol is a synchronization protocol for shared resources to avoid unbounded priority inversion and mutual deadlock due to wrong nesting of critical sect
Transactional memory
In computer science and engineering, transactional memory attempts to simplify concurrent programming by allowing a group of load and store instructions to execute in an atomic way. It is a concurrenc
Ease (programming language)
Ease is a general purpose parallel programming language. It is designed by Steven Ericsson-Zenith, a researcher at Yale University, the Institute for Advanced Science & Engineering in Silicon Valley,
Lease (computer science)
In computer science, a Lease is a contract that gives its holder specified rights to some resource for a limited period. Because it is time-limited, a lease is an alternative to a lock for resource se
Thundering herd problem
In computer science, the thundering herd problem occurs when a large number of processes or threads waiting for an event are awoken when that event occurs, but only one process is able to handle the e
Global interpreter lock
A global interpreter lock (GIL) is a mechanism used in computer-language interpreters to synchronize the execution of threads so that only one native thread (per process) can execute at a time. An int
Concurrency control
In information technology and computer science, especially in the fields of computer programming, operating systems, multiprocessors, and databases, concurrency control ensures that correct results fo
Double compare-and-swap
Double compare-and-swap (DCAS or CAS2) is an atomic primitive proposed to support certain concurrent programming techniques. DCAS takes two not necessarily contiguous memory locations and writes new v
Room synchronization
The room synchronization technique is a form of concurrency control in computer science. The room synchronization problem involves supporting a set of m mutually exclusive "rooms" where any number of
Software transactional memory
In computer science, software transactional memory (STM) is a concurrency control mechanism analogous to database transactions for controlling access to shared memory in concurrent computing. It is an
Modular serializability
No description available.
Language Of Temporal Ordering Specification
In computer science Language Of Temporal Ordering Specification (LOTOS) is a formal specification language based on temporal ordering of events. LOTOS is used for communications protocol specification
Two-phase locking
In databases and transaction processing, two-phase locking (2PL) is a concurrency control method that guarantees serializability.It is also the name of the resulting set of database transaction schedu
Asynchronous I/O
In computer science, asynchronous I/O (also non-sequential I/O) is a form of input/output processing that permits other processing to continue before the transmission has finished. A name used for asy
Priority inheritance
In real-time computing, priority inheritance is a method for eliminating unbounded priority inversion. Using this programming method, a process scheduling algorithm increases the priority of a process
Locks with ordered sharing
In databases and transaction processing the term Locks with ordered sharing comprises several variants of the Two phase locking (2PL) concurrency control protocol generated by changing the blocking se
Overlapped I/O
Overlapped I/O is a name used for asynchronous I/O in the Windows API. It was introduced as an extension to the API in Windows NT. Utilizing overlapped I/O requires passing an OVERLAPPED structure to
Non-lock concurrency control
In Computer Science, in the field of databases, non-lock concurrency control is a concurrency control method used in relational databases without using locking. There are several non-lock concurrency
Squatting attack
Squatting attack, in computer science, is a kind of DoS attack where a program interferes with another program through the use of shared synchronization objects in an unwanted or unexpected way. That
Atomic semantics
Atomic semantics is a type of guarantee provided by a shared by several processors in a parallel machine or in a network of computers working together.Atomic semantics are very strong. An atomic regis
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 even
Double-checked locking
In software engineering, double-checked locking (also known as "double-checked locking optimization") is a software design pattern used to reduce the overhead of acquiring a lock by testing the lockin
Event (synchronization primitive)
In computer science, an event (also called event semaphore) is a type of synchronization mechanism that is used to indicate to waiting processes when a particular condition has become true. An event i
In computer science, read–modify–write is a class of atomic operations (such as test-and-set, fetch-and-add, and compare-and-swap) that both read a memory location and write a new value into it simult
Critical section
In concurrent programming, concurrent accesses to shared resources can lead to unexpected or erroneous behavior, so parts of the program where the shared resource is accessed need to be protected in w
In computer science, load-linked/store-conditional (LL/SC), sometimes known as load-reserved/store-conditional (LR/SC), are a pair of instructions used in multithreading to achieve synchronization. Lo
Serializing tokens
In computer science, serializing tokens are a concept in concurrency control arising from the ongoing development of DragonFly BSD. According to Matthew Dillon, they are most akin to SPLs, except a to
Regular semantics
Regular semantics is a computing term which describes one type of guarantee provided by a data register shared by several processors in a parallel machine or in a network of computers working together
Barrier (computer science)
In parallel computing, a barrier is a type of synchronization method. A barrier for a group of threads or processes in the source code means any thread/process must stop at this point and cannot proce
In computer science, the test-and-set instruction is an instruction used to write (set) 1 to a memory location and return its old value as a single atomic (i.e., non-interruptible) operation. The call
In concurrency control of databases, transaction processing (transaction management), and various transactional applications (e.g., transactional memory and software transactional memory), both centra
Strong strict two-phase locking
No description available.
Global serializability
In concurrency control of databases, transaction processing (transaction management), and other transactional distributed applications, global serializability (or modular serializability) is a propert
Wait-for graph
A wait-for graph in computer science is a directed graph used for deadlock detection in operating systems and relational database systems. In computer science, a system that allows concurrent operatio
Readers–writer lock
In computer science, a readers–writer (single-writer lock, a multi-reader lock, a push lock, or an MRSW lock) is a synchronization primitive that solves one of the readers–writers problems. An RW lock
Reentrant mutex
In computer science, the reentrant mutex (recursive mutex, recursive lock) is a particular type of mutual exclusion (mutex) device that may be locked multiple times by the same process/thread, without
Mutual exclusion
In computer science, mutual exclusion is a property of concurrency control, which is instituted for the purpose of preventing race conditions. It is the requirement that one thread of execution never
Giant lock
In operating systems, a giant lock, also known as a big-lock or kernel-lock, is a lock that may be used in the kernel to provide concurrency control required by symmetric multiprocessing (SMP) systems
Modular concurrency control
No description available.
Index locking
In databases an index is a data structure, part of the database, used by a database system to efficiently navigate access to user data. Index data are system data distinct from user data, and consist
Multiple granularity locking
In computer science, multiple granularity locking (MGL) is a locking method used in database management systems (DBMS) and relational databases. In multiple granularity locking, locks are set on objec
Optimistic concurrency control
Optimistic concurrency control (OCC), also known as optimistic locking, is a concurrency control method applied to transactional systems such as relational database management systems and software tra
Semaphore (programming)
In computer science, a semaphore is a variable or abstract data type used to control access to a common resource by multiple threads and avoid critical section problems in a concurrent system such as
A seqlock (short for sequence lock) is a special locking mechanism used in Linux for supporting fast writes of shared variables between two parallel operating system routines. The semantics stabilized
Timestamp-based concurrency control
In computer science, a timestamp-based concurrency control algorithm is a non-lock concurrency control method. It is used in some databases to safely handle transactions, using timestamps.
Timestamping (computing)
In computing timestamping refers to the use of an electronic timestamp to provide a temporal order among a set of events. Timestamping techniques are used in a variety of computing fields, from networ
Multiversion concurrency control
Multiversion concurrency control (MCC or MVCC), is a concurrency control method commonly used by database management systems to provide concurrent access to the database and in programming languages t
Speculative multithreading
Thread Level Speculation (TLS), also known as Speculative Multithreading, or Speculative Parallelization, is a technique to speculatively execute a section of computer code that is anticipated to be e
Funnel (concurrent computing)
In Computer science, a funnel is a synchronization primitive used in kernel development to protect system resources. First used on Digital UNIX as a way to "funnel" device driver execution onto a sing
Construction and Analysis of Distributed Processes
CADP (Construction and Analysis of Distributed Processes) is a toolbox for the design of communication protocols and distributed systems. CADP is developed by the CONVECS team (formerly by the VASY te
Transactional Synchronization Extensions
Transactional Synchronization Extensions (TSX), also called Transactional Synchronization Extensions New Instructions (TSX-NI), is an extension to the x86 instruction set architecture (ISA) that adds
In computer science, read-copy-update (RCU) is a synchronization mechanism that avoids the use of lock primitives while multiple threads concurrently read and update elements that are linked through p
Volatile (computer programming)
In computer programming, particularly in the C, C++, C#, and Java programming languages, the volatile keyword indicates that a value may change between different accesses, even if it does not appear t
Snapshot isolation
In databases, and transaction processing (transaction management), snapshot isolation is a guarantee that all reads made in a transaction will see a consistent snapshot of the database (in practice it
Advanced Synchronization Facility
Advanced Synchronization Facility (ASF) is a proposed extension to the x86-64 instruction set architecture that adds hardware transactional memory support. It was introduced by AMD; the latest specifi
Operational transformation
Operational transformation (OT) is a technology for supporting a range of collaboration functionalities in advanced collaborative software systems. OT was originally invented for consistency maintenan
Monitor (synchronization)
In concurrent programming, a monitor is a synchronization construct that allows threads to have both mutual exclusion and the ability to wait (block) for a certain condition to become false. Monitors
Record locking
Record locking is the technique of preventing simultaneous access to data in a database, to prevent inconsistent results. The classic example is demonstrated by two bank clerks attempting to update th