Deadlock Prevention
Restrain the ways request can be made
Mutual Exclusion –
not required for sharable resources; must hold for nonsharable resources
Hold and Wait –
must guarantee that whenever a process requests a resource, it does not hold any other resources
Require process to request and be allocated all its resources before it begins execution, or allow process to request resources only when the process has none
Low resource utilization; starvation possible
No Preemption –
If a process that is holding some resources requests another resource that cannot be immediately allocated to it, then all resources currently being held are released
Preempted resources are added to the list of resources for which the process is waiting
Process will be restarted only when it can regain its old resources, as well as the new ones that it is requesting
Circular Wait –
impose a total ordering of all resource types, and require that each