Deadlock
Types of resources
serially reusable resource
consumable resource
Deadlock
Approaches to solving the problem
avoidance
prevention
detection and recovery
System model
states: process blocked, deadlocked; deadlock, safe states
system: resource graph, with resource and process nodes, and request, assignment edges
operations: request, acquire, release
Graph theory
sinks, isolated nodes
cycles, reach, knot
Deadlock detection with serially reusable resources
Graph reduction
Deadlock Theorem
Cycle Theorem (general)
Continuous deadlock detection: when do you have to look?
Expedient states and the Knot Theorem
Cycle Theorem (Single Unit Resources)
Single unit requests in expedient states
Deadlock recovery
lowest termination cost first
minimum cost recovery
process pre-emption
Deadlock prevention
necessary and sufficient conditions
collective request method
pre-emption
ordered request method
Deadlock avoidance
maximum claim graphs
Banker's algorithm
Consumable resources
general properties
known producers, unknown consumers: deadlock detection
order of reductions
theorems
recovery
known producers and known consumers
claim-limited state
General Resource Graph
Results
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Department of Computer Science
University of California at Davis
Davis, CA 95616-8562
Page last modified on 1/30/2000