GATE CSE 2022 Q26

Question

Which of the following statements is/are TRUE with respect to deadlocks?
A) Circular wait is a necessary condition for the formation of deadlock.
B) In a system where each resource has more than one instance, a cycle in its wait-for graph indicates the presence of a deadlock.
C) If the current allocation of resources to processes leads the system to unsafe state, then deadlock will necessarily occur.
D) In the resource-allocation graph of a system, if every edge is an assignment edge, then the system is not in deadlock state.

Accepted Answer

Official answer: A) Circular wait is a necessary condition for the formation of deadlock.; D) In the resource-allocation graph of a system, if every edge is an assignment edge, then the system is not in deadlock state.. Explanation: Evaluating each statement: - (A) Circular wait is a necessary condition for the formation of deadlock: TRUE. The four Coffman conditions necessary for deadlock to occur are Mutual Exclusion, Hold and Wait, No Preemption, and Circular Wait. If any one of these conditions does not hold, deadlock cannot occur. - (B) In a system where each resource has more than one instance, a cycle in its wait-for graph indicates the presence of a deadlock: FALSE. A wait-for graph is defined only for systems where each resource type has a single instance. In multi-instance resource systems, a cycle in a Resource Allocation Graph (RAG) is a necessary condition, but not a sufficient condition for deadlock. - (C) If the current allocation of resources to processes leads the system to unsafe state, then deadlock will necessarily occur: FALSE. An unsafe state is not necessarily a deadlocked state; it simply means the system cannot guarantee avoidance of deadlock if processes request their maximum resources. If processes do not demand their maximum claims, deadlock might not occur. - (D) In the resource-allocation graph of a system, if every edge is an assignment edge, then the system is not in deadlock state: TRUE. If every edge is an assignment edge (i.e., there are no request/claim edges), no process is waiting for any resource, so no process can be in a blocked/deadlocked state.

Answer

A) Circular wait is a necessary condition for the formation of deadlock.

Answer

B) In a system where each resource has more than one instance, a cycle in its wait-for graph indicates the presence of a deadlock.

Answer

C) If the current allocation of resources to processes leads the system to unsafe state, then deadlock will necessarily occur.

Answer

D) In the resource-allocation graph of a system, if every edge is an assignment edge, then the system is not in deadlock state.

Which of the following statements is/are TRUE with respect to deadlocks?

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Which of the following statements is/are TRUE with respect to deadlocks?

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Which of the following statements is/are TRUE with respect to deadlocks?

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