Recent questions tagged deadlock-prevention-avoidance-detection / GATE Overflow for GATE CSE

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151

UPPCL AE 2018:52
Consider the following implementation as a solution to the critical section problem for two processes $\text{P}_{0}$ and $\text{P}_{1}$ with id $0$ and $1,$ respectively. int flag[2] = {0,0}; int turn = 0; void lock (int id) /* ... exclusion is guaranteed Mutual exclusion is guaranteed if $\text{S1}$ and $\text{S2}$ are interchanged Solution leads to a deadlock None of the above

Consider the following implementation as a solution to the critical section problem for two processes $\text{P}_{0}$ and $\text{P}_{1}$ with id $0$ and $1,$ respectively....

admin

222 views

admin asked Jan 5, 2019

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1 answer

152

UGC NET CSE | December 2018 | Part 2 | Question: 70
Suppose a system has $12$ instances of some resource with $n$ processes competing for that resource. Each process may require $4$ instances of the resources. The maximum value of $n$ for which the system never enters into deadlock is $3$ $4$ $5$ $6$

Suppose a system has $12$ instances of some resource with $n$ processes competing for that resource. Each process may require $4$ instances of the re...

Arjun

2.5k views

Arjun asked Jan 2, 2019

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0 answers

153

Relating process termination and deadlock with progress requirement of the solution to the critical section problem

Many problems on gateoverflow asks whether the given code satisfies progress requirement of the solution for the critical section problem. Most of these code contain mult...

Raj Singh 1

1.5k views

Raj Singh 1 asked Jan 1, 2019

1 votes

0 answers

154

Test by Mentors MOCK doubt
Which of the following situations deadlock will occur ? Process requests all the required resources in the beginning Process requests resource only if it has none Process orders resources in increasing order of enumeration Resources are immediately allocated to process holding some resources

Which of the following situations deadlock will occur ? Process requests all the required resources in the beginning Process requests resource only if it has none ...

jatin khachane 1

360 views

jatin khachane 1 asked Jan 1, 2019

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0 answers

155

Synchronization
How Bounded waiting is Satisfied in Option B?

How Bounded waiting is Satisfied in Option B?

ghostman23111

189 views

ghostman23111 asked Dec 30, 2018

1 votes

1 answer

156

GATE Overflow | Mock GATE | Test 1 | Question: 63
A system is having user processes $P_1, P_2, \dots , P_N$ each requiring $Q_N, Q_{N-1}, \dots , Q_1$ number of resource instances of resource $R$. The minimum number of resource instances of $R$ to guarantee that deadlock will not occur is $NQ_N - N+1$ $NQ_1 + N-1$ $(Q_1 + Q_2 + … + Q_N) + N – 1$ $(Q_1 + Q_2 + … + Q_N) + 1 – N$

A system is having user processes $P_1, P_2, \dots , P_N$ each requiring $Q_N, Q_{N-1}, \dots , Q_1$ number of resource instances of resource $R$. The minimum number of r...

Ruturaj Mohanty

742 views

Ruturaj Mohanty asked Dec 27, 2018

2 votes

1 answer

157

self doubt Deadlock
is there deadlock in the concurrent execution of two thread given below? void laurel() { lock_acquire(mutex); /* do something */ lock_acquire(file1); /* write to file 1 */ lock_acquire(file2); /* write to file 2 */ lock_release(file1); lock_release(mutex); ... (file1); lock_release(mutex); } i'm not getting any deadlock. please comment below if you find any. *Idon't have answer.

is there deadlock in the concurrent execution of two thread given below?void laurel() { lock_acquire(mutex); /* do something */ lock_acquire(file1); ...

aambazinga

1.1k views

aambazinga asked Dec 24, 2018

0 votes

1 answer

158

Deadlock condition in synchronization
Please describe the Deadlock Condition in synchronization and when will be synchronization possible and condition ..?

Please describe the Deadlock Condition in synchronization and when will be synchronization possible and condition ..?

Rackson

437 views

Rackson asked Dec 14, 2018

1 votes

2 answers

159

synchronization
does it guarantee mutual exclusion and deadlock prevention?

does it guarantee mutual exclusion and deadlock prevention?

Rahul_Rathod_

949 views

Rahul_Rathod_ asked Dec 12, 2018

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0 answers

160

Test Series Question
What should be the answer?

What should be the answer?

smsubham

489 views

smsubham asked Dec 7, 2018

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0 answers

161

previous
https://gateoverflow.in/2263/gate1997-6-7 1. They said at least 4 resource are required. First p1 comes takes two system resource, then p2 comes takes 1 system resource, then p3 comes takes 1 system resource. Now P3 needs one more resource so it is ... process keeps track when the other process leaves resource, which part of the os performs this function? is it done by using semaphores?

https://gateoverflow.in/2263/gate1997-6-71. They said at least 4 resource are required.First p1 comes takes two system resource, then p2 comes takes 1 system resource, th...

Swapnil Naik

234 views

Swapnil Naik asked Nov 16, 2018

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0 answers

162

please solve this Q

kallu singh

255 views

kallu singh asked Nov 16, 2018

0 votes

0 answers

163

Bankers algorithms
Please help in understanding how to solve bankers algorithms with example as I get confuse how to start solving because sometimes we calculate need of the process ,sometimes available from the given question, sometime instance of resources are given else ... used in question. Please help in understanding the different scenarios to be covered and how to tackle each problem. Thanks

Please help in understanding how to solve bankers algorithms with example as I get confuse how to start solving because sometimes we calculate need of the process ,someti...

Mayankprakash

438 views

Mayankprakash asked Nov 9, 2018

1 votes

2 answers

164

Deadlock
If the total number of resources available is 6 and each process requires 3 instances of a resource to complete execution. Then what is the number of processes that can exist in this system without causing a deadlock?

If the total number of resources available is 6 and each process requires 3 instances of a resource to complete execution. Then what is the number of processes that can e...

Dhillu Thambi

559 views

Dhillu Thambi asked Nov 4, 2018

0 votes

1 answer

165

safe and unsafe state
if there is no allocation sequence that allows the processes to finish executing, then the system is in an unsafe state. This is not equivalent to the "If the system is in an unsafe state, then there is no allocation sequence that allows the processes to finish executing

if there is no allocation sequence that allows the processes to finish executing, then the system is in an unsafe state.This is not equivalent to the "If the system is i...

Gurdeep Saini

2.1k views

Gurdeep Saini asked Nov 3, 2018

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0 answers

166

Operating Systems
To check that a mutual exclusion algorithm is not free from deadlock,is it necessary to check if the entire processes in the system are in deadlock- If there are 5 processes in the system- P0,P1,P2,P3,P4 and if we have to prove that the ... definitely in deadlock- This means it is not necessary for all processes in the system to be in deadlock to say deadlock has occurred?

To check that a mutual exclusion algorithm is not free from deadlock,is it necessary to check if the entire processes in the system are in deadlock-If there are 5 proces...

skywalker_19

294 views

skywalker_19 asked Oct 23, 2018

0 votes

3 answers

167

self doubt in OS(galvin)
All safe states are deadlock free. But we can go to deadlock with some combination of sequence? So if the question is, from the safe state can we enter deadlock? Ans should be YES. please give your thought

All safe states are deadlock free. But we can go to deadlock with some combination of sequence? So if the question is, from the safe state can we enter deadlock? Ans shou...

Vegeta

927 views

Vegeta asked Oct 22, 2018

0 votes

1 answer

168

Mutual Exclusion vs. Hold and Wait
In the context of a Deadlock, what is the difference between Mutual Exclusion and Hold and Wait ? In case of Hold and Wait, a process holds atleast one resource. Doesn't this correspond to Mutual Exclusion, where atleast one resource is held in a non-shareable mode ??

In the context of a Deadlock, what is the difference between Mutual Exclusion and Hold and Wait ?In case of Hold and Wait, a process holds atleast one resource. Doesn't t...

the_bob

1.0k views

the_bob asked Sep 25, 2018

0 votes

0 answers

169

Test and Set Lock(TSL)
In case of TSL we are aware of the following instructions: 1. TSL LOCK, Ro 2. CMP Ro, #0 3. JNZ step1 Now, the initial value of LOCK is 0 If process Po comes and executes line 1 and if it gets preempted, then Ro = 0 and LOCK = 1 Now, If process P1 ... able to enter the CS...right? So, in this way, Po and P1 both will get stuck...right? and so is there a chance of deadlock?

In case of TSL we are aware of the following instructions: 1. TSL LOCK, Ro 2. CMP Ro, #0 3. JNZ step1 Now, the initial value of LOCK is 0 If process Po...

garvit_vijai

1.4k views

garvit_vijai asked Sep 20, 2018

0 votes

1 answer

170

self doubt
why spinlock requires context switch ?

why spinlock requires context switch ?

vijju532

290 views

vijju532 asked Aug 28, 2018

1 votes

2 answers

171

Self-doubt
Process maximum demand currently holds P1 70 45 P2 60 40 P3 60 X P4 40 Y If a system has total of 150 units of resource , identify which of the following values of X and Y the above system will be in safe state? 1. X = 40 , Y = 20 2. X = 50 , Y = 10 3. X = 30 , Y = 20 4. X = 20 , Y = 30

Processmaximum demandcurrently holdsP17045P26040P360XP440YIf a system has total of 150 units of resource , identify which of the following values of X and Y the above sys...

Sid865

1.8k views

Sid865 asked Aug 21, 2018

0 votes

2 answers

172

Self doubt
How to solve the question involving the calculation of safe sequence when the resource allocation graph is given instead of the table. Eg. In the question below..What should be the approach to solve the question??? Plzz explain..

How to solve the question involving the calculation of safe sequence when the resource allocation graph is given instead of the table. Eg. In the question below..What sho...

Sid865

672 views

Sid865 asked Aug 21, 2018

1 votes

2 answers

173

Self doubt
Identify the incorrect statement : 1. If there are no cycles in resource allocation graph then there is no deadlock. 2. If there is only one instance per resource type and resource allocation graph has a cycle then there is a deadlock. 3. If there is more than ... for some resource type and resource allocation graph has a cycle , there may or may not be a deadlock. 4. All of these

Identify the incorrect statement :1. If there are no cycles in resource allocation graph then there is no deadlock.2. If there is only one instance per resource type and ...

Sid865

2.3k views

Sid865 asked Aug 21, 2018

0 votes

3 answers

174

MadeEasy Workbook: Operating System - Deadlock Prevention Avoidance Detection
Assume a system with four resource types, C=(6,4,4,2), andthe maximum claim table below. The resource allocator isconsidering allocating resources according to the tablebelow. Is this state safe? Why or why not? MaximumClaim Current ... 2 1 0 1 0 1 0 1 FIND WHETHER STATE IS SAFE OR NOT a-safe b-unsafe c-deadlock

Assume a system with four resource types, C=(6,4,4,2), andthe maximum claim table below. The resource allocator isconsidering allocating resources according to the tableb...

mobashshir

2.9k views

mobashshir asked Aug 15, 2018

1 votes

1 answer

175

#OS Deadlock Necessary Conditions doubt
As Galvin States we have for necessary conditions to have a deadlock as - 1) M.E 2) Hold and wait 3) No preemption 4) Circular wait. Now, for a deadlock to happen does all four these conditions need to be present/true ... I mean, say, there's no M.E therefore can we straightaway declare there's deadlock without checking for other three conditions?

As Galvin States we have for necessary conditions to have a deadlock as -1) M.E2) Hold and wait 3) No preemption4) Circular wait. Now, for a deadlock to happen does all f...

iarnav

1.1k views

iarnav asked Aug 9, 2018

0 votes

0 answers

176

OPERATING SYSTEM GALVIN DEADLOCK
In the deadlock chapter, in resource allocation graph algorithm, it is given that detecting a cycle takes O(n^2) operations... But we can find cycle in O(n+m) operations, using DFS. Why they have not considered this.. or if they have considered, what am I missing. Or is it that they have given worst case time assuming #edges(i.e; m)=n(n-1)/2 which would give O(n^2)?

In the deadlock chapter, in resource allocation graph algorithm, it is given that detecting a cycle takes O(n^2) operations... But we can find cycle in O(n+m) operations,...

aambazinga

256 views

aambazinga asked Aug 2, 2018

0 votes

0 answers

177

deadlock
If ‘m’ processes share ‘n’ resources of the same type, the maximum need of each process does not exceed ‘n’ and the sum of all their maximum needs is always less than ‘m+n’. In this case: (a) Deadlock can never occur (c) Deadlock has to occur (b) Deadlock may occur (d) None

If ‘m’ processes share ‘n’ resources of the same type, the maximum need of each process doesnot exceed ‘n’ and the sum of all their maximum needs is always le...

prabhat0987

256 views

prabhat0987 asked Jul 27, 2018

4 votes

3 answers

178

Critical Section
Consider the following code to solve the critical section problem for two processes P0 and P1. Initially flag [i] contain false for i = 0 and 1. Assume i refers to the current process Pi and j refers the other process Pj. If two processes ... following satisfy the above solution? A. Mutual exclusion and progress B. Mutual exclusion and bounded wait C. Progress D. None of these

Consider the following code to solve the critical section problem for two processes P0 and P1. Initially flag [i] contain false for i = 0 and 1.Assume i refers to the cur...

Na462

4.5k views

Na462 asked Jul 18, 2018

0 votes

0 answers

179

Processes
Ans. D I don't know why C cant be the answer because its independent processes but independent processes can access the same resources even they are completely different like say two independent processes working on two different files but still they both have to access the Disk. So there can be the situation of Deadlock. Isn't ? Please Correct Me :/

Ans. DI don't know why C cant be the answer because its independent processes but independent processes can access the same resources even they are completely different l...

Na462

512 views

Na462 asked Jul 12, 2018

0 votes

0 answers

180

Deadlock Sequence
Consider two processes P1 and P2, each needed 3 resources 1, 2 and 3 in a database. If each processes ask them in any order, then the number of ways possible in which system is guaranteed to be deadlock free ________. Answer. 120 Please Tell me the Approach :)

Consider two processes P1 and P2, each needed 3 resources 1, 2 and 3 in a database. If each processes ask them in any order, then the number of ways possible in which sy...

Na462

289 views

Na462 asked Jul 9, 2018

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