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Deadlock management

Principle

Resource allocation policy

schemas

advantages

disadvantages

Prevention

conservative

request all resources at once

preemption

resource

ordering

processes with single burst of activity

resources whose state can be saved and restored easily

problem solved by design

inefficient, delays process initiation

preempts more than necessary,

needs to be restarted

preempts without need

Detection

very liberal

invoked periodically to test deadlock

does not delay process initiation

preemption losses

Avoidance

midway between conservative and liberal

search to find at least one safe path

no preemption needed

resources must be known, long blockings

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