Test by Bikram | Operating Systems | Test 2 | Question: 16

Question

Which of the following statements are not true?

1. All unsafe states are deadlocks
2. A deadlock state is unsafe state
3. A system is in safe state only if there exists a safe sequence
4. A state is said to be safe if the system can allocate resources to few processes even if all of them suddenly request their maximum number of resources.

• A. $3$ & $4$ only
• B. $1$ & $4$ only
• C. $2$ & $3$ only
• D. $1$, $3$ & $4$ only

Comments

All unsafe states are deadlocks: $NO$ Reason

Answer 1

Not all unsafe states are deadlocks.  In safe state there is some scheduling order in which every process can run  to completion even if all of them suddenly request their maximum number of  resources.

Comments

okay.

---

A state is called safe if it is not deadlocked and there is some scheduling order in which every process can run to completion even if all of them suddenly requests their maximum number of resources immediately.

This is the reason why statement 4 is incorrect.

While in question statement 4 says "A state is said to be safe if the system can allocate resources to few processes even if all of them suddenly request their maximum number of resources. " means only few process can run to completion . That is wrong anyway.

Reference:

1. http://people.sabanciuniv.edu/ysaygin/documents/lectures/CS307_lecture_6.pdf

---

Sir

Not all unsafe states are deadlock,

may you help me out by giving scenario,

once we enter into the unsafe state,it won,t proceed, got hanged

Answer 2

In Deadlock Avoidance / Banker's Algorithm

A safe state is a state in which there exists a sequence of execution.

An unsafe state is a state where there can't be any execution sequence.

A deadlocked state is when the availability of resources is 0.

 

Option B

---

Check this: https://gateoverflow.in/44404/isro-2013-58 (Everyone answered wrong here, except Dexter)