NIELIT 2017 DEC Scientist B - Section B: 21

Question

A system has $3$ processes sharing $4$ resources. If each process needs a maximum of $2$ units then, deadlock

• A. Can never occur
• B. Has to occur
• C. May occur
• D. None of the options 

Comments

lets take worst case .

each need 2 resource = then assign 1,1,1 then 1 is left give it to any one , so atleast one process is always run. hence no deadlock.

A

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https://gateoverflow.in/55698/isro2016-47

Answer 1

(A) Can never occur   

Answer 2

Min requirement of all processes is 3x1 + 1=4 which is not exceeding the available number of resources, which is 4 in the system, and therefore satisfies the necessary & condition for deadlock-free execution, hence option A is right

Answer 3

 

If the system is deadlocked, it implies that each process is holding one resource and is waiting for one more. Since there are 3 processes and 4 resources, one process must be able to obtain two resources. This process requires no more resources and therefore it will return its resources when done.

Hence,Option(A)deadlock can never occur.