Deadlock Problem

Q1. What is Deadlock Problem?
Ans. A set of block processes, each holding a resource and waiting to acquire a resource held by another process in the set.

Figure: Deadlock

In figure we can see a deadlock as process P2 is waiting for resource R1 which is currently held by process P1. Process P1 is waiting for resources R2 and is not releasing resource R11. Both processes will wait forever, so a cycle is form, a cycle, in the graph means that there is a deadlock involving the process and resource.

In this example, the cycle is

P2-R1-P1-R2-P2