COMP 007 - Week 7 to 8 - Deadlocks

Deadlock

A condition where a process waits for a resource that is assigned to another process that is also waiting for a resource.

Starvation

A condition where a low-priority process gets blocked due to high-priority processes being executed.

Mutual Exclusion

At least one resource must be held in a non-sharable mode.

Hold and Wait

A process must be holding at least one resource and waiting for at least one resource currently held by another process.

No Preemption

Once a process is holding a resource, that resource cannot be forcibly taken away until the process voluntarily releases it.

Circular Wait

A situation where two or more processes form a circular chain, each waiting for a resource held by the next process.

Resource Allocation Graph

A graphical representation where circles represent processes and squares represent resources to model system resources.

Banker’s Algorithm

A deadlock avoidance algorithm that checks the safety of resource allocation before proceeding.

Aging

A technique used to gradually increase the priority of a low-priority process over time.

Resource Allocation

The management of system resources by the OS to ensure proper execution of processes.

Input-Processing-Output stages

The different stages through which a process goes, including requesting and using resources.

Detection and Recovery

The OS's task to detect deadlocks and recover from them using various strategies.

Ostrich Algorithm

A method where the OS assumes deadlock is unlikely and ignores potential deadlocks.

Safe state

A system state where processes can be allocated resources without causing a deadlock.

Unsafe state

A system state where the allocation of resources may lead to a deadlock.

Preempt resources

To forcibly take resources away from one process to allocate them to another.

Rollback

To return the state of resources to a previous safe point to resolve a deadlock.

Deadlock Conditions

The necessary conditions that must occur simultaneously for a deadlock to happen.

Blocking State

A state where a process cannot proceed because it is waiting for resource allocation.

CPU

Central Processing Unit, the primary component of a computer system responsible for execution of instructions.

I/O devices

Input/Output devices that facilitate interaction with the computer system.

Resource allocation techniques

Methods employed to manage the allocation and deallocation of resources among processes.

Deadly embrace

An early term used to describe deadlock situations in computing.

Priority in Resource Allocation

A mechanism used to determine which process gets access to the resources first based on priority.

Circular Resource Allocation

A scenario in which resources are allocated in a circular manner leading to potential deadlocks.

Process states

Stages that indicate the current status of a process in its execution cycle.

Process management

The act of managing the execution and resource allocation of processes in an operating system.

Expected resource requests

Predictions made about the resources that will be needed by each process during execution.

Resource Availability

The current number of resources that are available for allocation in the system.

Resource Request Failures

Situations in which a process requests resources that are not currently available.

System deadlocks

A state where two or more processes are unable to proceed because each is waiting on the other.

Resource request approvals

A decision made by the OS regarding whether to allow a process's request for resources.

Deadlock-free system

A system where algorithms and techniques are employed to ensure that deadlocks cannot occur.

Non-sharable resources

Resources that cannot be shared among multiple processes simultaneously.

Deadlock prevention techniques

Strategies to prevent deadlocks by ensuring that at least one of the necessary conditions for deadlock cannot hold.

Resource claiming

The action of a process requesting and holding some resources while waiting for others.

Dijkstra and Habermann

The developers associated with the creation of the Banker's Algorithm.

Max resource attribute

The maximum number of resources that a process may require, specified in the Banker’s Algorithm.

Resource allocation methods

The various approaches used to allocate system resources to processes.

Priority numbers

Numerical values assigned to resources to control access and prevent deadlocks.

Deadlock management policies

Rules and strategies implemented by the OS to handle situations of deadlock.

Decoupling resource requests

Separating the resource request phase from execution to minimize deadlock risk.

Resource dependency

The relationship between processes and the resources they require to function.

Sequential resource requests

Requests made for resources in a specific order, not allowing arbitrary requests.

Resource allocation failures

Instances where resource requests by processes cannot be fulfilled.

Finite resource availability

The limited nature of resources available for allocation in a computer system.

Process execution requirements

The specific resources and conditions that processes must meet to execute properly.

Deadlock occurrence

The event in which processes become unable to proceed due to mutual waiting for resources.

Safety check

An assessment to determine if resource allocation results in a safe or unsafe state.

Request a resource

The action taken by a process to obtain the necessary resources for execution.

Resource release

The action of a process freeing up resources that it no longer needs.

Definition of deadlock

The precise characterization of the conditions under which processes are deadlocked.

Detection algorithms

Procedures used by the OS to identify deadlocks in the system.

Examples of deadlock

Illustrations of scenarios that exemplify the phenomenon of deadlock among processes.

State of the system

The current configuration of processes and resources that determines whether a deadlock can occur.

Determining resource allocation

The process of deciding how to assign available resources among competing processes.

OS deadlock handling strategies

Methods employed by operating systems to manage and resolve deadlock occurrences.

Graphical representation of resources

A visual diagram used to depict the relationships between processes and resources in the system.