Test: Deadlock- 2 - Computer Science Engineering (CSE) MCQ

Banker’s algorithm resources will only be allocated if system will remain in SAFE state (DEADLOCK can’t occur if system is in SAFE state), so performing DEADLOCK AVOIDANCE.

For deadlock four necessary condition are to be met
(i) Mutual exclusion
(ii) Non-preemption
(iii) Circular wait
(iv) Partial allocation [Bounded waiting]

Deadlock can’t take place if resources must be requested in same order by process. For deadlock, circular wait is a must condition.

To ensure that deadlock will not occur in a system in which processes are in HOLD and WAIT condition, a process requires to request all resources before it begins execution, or allow process to request resources only when the process has no other resources already allocated.

Reusable resource: A resource, such as a CPU or tape transport, that is not rendered useless by being used. A magnetic disk or tape can be used often indefinitely and are to be regarded as reusable resources. Compare consumable resources.

Total printers = 12
Printers allocated to user 1, user 2 and user 3 are 7, 1 and 2 respectively

So, only safest sequence is V₃ first then either or V₃. So, operating system will grant printer to user 3 only.

(i) Deadlock is unsafe state
(ii) The unsafe state may lead to deadlock.
(iii) Clearly deadlock state is subset of unsafe state.
Its not compulsory that unsafe state always result in deadlock

Deadlock prevention scheme handles the dead lock by confirms that either of the four necessary condition for deadlock doesn’t occur. Hence a resource request may not be granted even if the resulting state is safe.

Starvation can occur as each time a process requests a resource it has to release all its resources. Now, maybe the process has not used the resources properly yet. This will happen again when the process requests another resource. So, the process starves for proper utilisation of resources.

Deadlock will not occur as it is similar to a deadlock prevention scheme.