Need Matrix (Max − Allocation)
Deadlock Detection
Enter each process’s current outstanding Request. This differs from the Max matrix used by Banker’s avoidance check.
Outstanding Request matrix
Deadlock Method Library
RAG
Resource Allocation Graph
Prevent
Break Coffman Conditions
Resource Allocation Graph: cycles reveal deadlock for single-instance resources and possible deadlock for multiple instances.
Detection: repeatedly find a process whose outstanding request can be satisfied, then release its allocation.
Prevention: deny at least one condition: mutual exclusion, hold-and-wait, no preemption, or circular wait.
Avoidance: use Banker's Algorithm to enter only states with a safe sequence.
Recovery: select a victim process, abort it or preempt resources, then roll back safely.