The Banker's algorithm is a resource allocation and deadlock avoidance algorithm developed by Edsger W. Dijkstra that tests for safety by simulating the allocation of predetermined maximum possible amounts of all resources, and then makes an "s-state" safe state check to test for possible deadlock conditions for all other pending activities, before deciding whether allocation should be allowed to continue.

When a new process enters a system, it must declare the maximum number of instances of each resource type that it may ever claim; clearly, that number may not exceed the total number of resources in the system. Also, when a process gets all its requested resources it must return them in a finite amount of time.