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December 28, 2023Question 14305 – Operating-Systems
Consider a computer system with multiple shared resource types, with one instance per resource type. Each instance can be owned by only one process at a time. Owning and freeing of resources are done by holding a global lock (L). The following scheme is used to own a resource instance:
function OWNRESOURCE(Resource R)
Acquire lock L // a global lock
if R is available then
Acquire R
Release lock L
else
if R is owned by another process P then
Terminate P, after releasing all resources owned by P
Acquire R
Restart P
Release lock L
end if
end if
end function
Which of the following choice(s) about the above scheme is/are correct?
Correct Answer: D
(1) True,
The scheme ensures deadlock free operation, as there is no hold-and-wait condition possible.
(2) True,
The scheme may lead to priority inversion problems, and hence livelock is possible.
(3) False,
Mutual exclusion is satisfied as only one process can acquire and release locks at a time.
(4) True,
The scheme may lead to starvation. For example, the priority process can get scheduled repeatedly and keeps on killing the lower priority processes. Hence, a low priority process may strave.