# Deadlock

 Question 1
Which of the following statements is/are TRUE with respect to deadlocks?
MSQ
 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.
GATE CSE 2022   Operating System
Question 1 Explanation:
 Question 2
An aid to determine the deadlock occurrence is
 A resource allocation graph B starvation graph C inversion graph D none of the above
ISRO CSE 2020   Operating System
Question 2 Explanation:

 Question 3
Raymonds tree based algorithm ensures
 A no starvation, but deadlock may occur in rare cases B no deadlock, but starvation may occur C neither deadlock nor starvation can occur D deadlock may occur in cases where the process is already starved
ISRO CSE 2020   Operating System
Question 3 Explanation:
 Question 4
Consider the following snapshot of a system running n concurrent processes. Process $i$ is holding $X_i$ instances of a resource R, $1\leq i\leq n$. Assume that all instances of R are currently in use. Further, for all $i$, process $i$ can place a request for at most $Y_i$ additional instances of R while holding the $X_i$ instances it already has. Of the n processes, there are exactly two processes p and q such that $Y_p=Y_q=0$. Which one of the following conditions guarantees that no other process apart from p and q can complete execution?
 A $X_p+X_q \lt Min \{Y_k|1\leq k\leq n,k\neq p,k\neq q\}$ B $X_p+X_q \lt Max \{Y_k|1\leq k\leq n,k\neq p,k\neq q\}$ C $Min(X_p,X_q)\geq Min \{Y_k|1\leq k\leq n,k\neq p,k\neq q\}$ D $Min(X_p,X_q)\leq Max \{Y_k|1\leq k\leq n,k\neq p,k\neq q\}$
GATE CSE 2019   Operating System
Question 4 Explanation:
 Question 5
Consider a system having m resources of the same type. These resources are shared by 3 processes A,B,C, which have peak time demands of 3,4,6 respectively. The minimum value of m that ensures that deadlock will never occur is:
 A 11 B 12 C 13 D 14
ISRO CSE 2018   Operating System
Question 5 Explanation:

There are 5 questions to complete.

### 2 thoughts on “Deadlock”

1. Sir, In question no. 16, Question is not written right, sequence is “as bs cs ae ds ce es fs be de gs ee fe hs ge he”, Here no activity is having the e symbol associated with them.

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• Thank you for your suggestion. We have updated it.

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