Which of the following statements is/are TRUE with respect to deadlocks?
Topic-wise GATE CS PYQs with verified steps
GATE CSE 2022 · Q26
Time
Select all that applyOne or more correct
Solution
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.
DeadlockEvaluating 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.
Try the question first, then check your work.
Examiner trap
Review Coffman's four necessary conditions for deadlock, safe/unsafe state definitions, and the properties of Resource Allocation Graphs.
This Deadlock previous year question is Q26 of the GATE CSE 2022 paper. Find more GATE CSE PYQs on Deadlock in Operating Systems, or browse all GATE CSE PYQs.
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Deadlock has 11 GATE CSE PYQs across 10 papers from 2014 to 2026. 2 of them are 1-mark MSQs like this one, and it is the only one in GATE CSE 2022.
How GATE tests DeadlockIndependent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.