In
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includi ...
, resource contention is a conflict over access to a
shared resource
In computing, a shared resource, or network share, is a computer resource made available from one host to other hosts on a computer network.
It is a device or piece of information on a computer that can be remotely accessed from another compu ...
such as
random access memory,
disk storage,
cache memory
In computing, a cache ( ) is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewher ...
, internal
bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
es or external network devices. A resource experiencing ongoing contention can be described as oversubscribed.
Resolving resource contention problems is one of the basic functions of
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...
s. Various low-level mechanisms can be used to aid this, including
lock
Lock(s) may refer to:
Common meanings
*Lock and key, a mechanical device used to secure items of importance
*Lock (water navigation), a device for boats to transit between different levels of water, as in a canal
Arts and entertainment
* ''Lock ...
s,
semaphores,
mutex
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 is designed to enforce a mutual exclusion concur ...
es and
queues. The other techniques that can be applied by the operating systems include intelligent scheduling, application mapping decision, and
page coloring.
Access to resources is also sometimes regulated by queuing; in the case of computing time on a
CPU the controlling
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
of the
task queue is called a
scheduler.
Failure to properly resolve resource contention problems may result in a number of problems, including
deadlock
In concurrent computing, deadlock is any situation in which no member of some group of entities can proceed because each waits for another member, including itself, to take action, such as sending a message or, more commonly, releasing a loc ...
,
livelock, and
thrashing.
Resource contention results when multiple processes attempt to use the same shared resource. Access to memory areas is often controlled by semaphores, which allows a pathological situation called a deadlock, when different
threads or
processes try to allocate resources already allocated by each other. A deadlock usually leads to a program becoming partially or completely unresponsive.
In recent years, research on the contention is more focused on the resources in the
memory hierarchy, e.g., last-level caches, front-side bus, memory socket connection.
See also
*
Bus contention
Bus contention is an undesirable state in computer design where more than one device on a bus attempts to place values on it at the same time.
Bus contention is the kind of telecommunication contention that occurs when all communicating devi ...
*
Cache coherence
*
Collision avoidance (networking)
In transportation, collision avoidance is the maintenance of systems and practices designed to prevent vehicles (such as aircraft, motor vehicles, ships, cranes and trains) from colliding with each other. Examples include:
* Airborne collision av ...
*
Resource allocation
In economics, resource allocation is the assignment of available resources to various uses. In the context of an entire economy, resources can be allocated by various means, such as markets, or planning.
In project management, resource allocati ...
References
Computational resources
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