At least 1 necessary condition does not hold
- Mutual Exclusion: not required for sharable resources; must hold for non-sharable resources.
- Hold-and-Wait: can not request new when holding resources.
- Protocol 1: request all resources before it begins execution
- Protocol 2: request resources only when the process has none.
- Low resource utilization; starvation possible.
- No Preemption: preempt resources from processes
- Protocol 1: If a request can not be satisfied then preempt all resources held and block
- Protocol 2: Preempt only if resources are needed by another running process
- Requires resource state to be easily restored
- Circular Wait: Block any request that results in a cycle.
- Impose a total ordering of all resource types, and require that each process requests resources in an increasing order
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