Operating Systems, unit: Deadlocks. Core concepts, terminology, and worked-example cues a college student meets for this unit, building on prior units without repeating them. Front: a term, concept, or short problem cue. Back: the definition, explanation, or answer.
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- What is deadlock?
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A situation where a set of processes are each waiting for a resource held by another, with none able to proceed- What are the four necessary conditions for deadlock, known as the Coffman conditions?
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Mutual exclusion, hold and wait, no preemption, and circular wait- What is mutual exclusion, as a deadlock condition?
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At least one resource must be held in a non-shareable way- What is hold and wait, as a deadlock condition?
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A process holds at least one resource while waiting for additional ones held by others- What is no preemption, as a deadlock condition?
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Resources cannot be forcibly taken away from a process; they must be released voluntarily- What is circular wait, as a deadlock condition?
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A cycle of processes exists, each waiting for a resource held by the next- What is deadlock prevention?
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Designing the system so at least one of the four necessary conditions can never occur- What is deadlock avoidance?
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Dynamically analyzing resource requests to ensure the system never enters an unsafe state- What is the Banker's Algorithm used for?
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A deadlock avoidance algorithm that checks if granting a resource request leaves the system in a safe state- What is a safe state, in deadlock avoidance terms?
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A state where the system can allocate resources to all processes in some order without deadlock- What is deadlock detection?
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Allowing deadlock to occur, then periodically checking for it using resource allocation graphs- What is a resource allocation graph?
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A diagram showing which processes hold and request which resources, used to detect deadlock cycles- What is deadlock recovery?
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Resolving a detected deadlock, typically by terminating processes or preempting resources- What is process termination as a deadlock recovery method?
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Killing one or more deadlocked processes to break the cycle- What is resource preemption as a deadlock recovery method?
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Forcibly taking a resource from one process and giving it to another to break the deadlock
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