Solution
Here, we are given that all locks are non-reentrant, meaning that if a thread holds a lock A, it has to release lock A before it can acquire lock A again. If a thread tries to acquire a lock when it is not available, the thread blocks.
We are asked to mind the minimum value of x and y such that deadlock may occur. Here x denotes the number of threads and y denotes the number of locks used by the multi-threaded program P. In this problem, we have to think of scenarios in the program code through which deadlock may occur. Let us start from the minimum possible combination x=1 and y=1 (option D). Starting from this option helps us in a way. If we find a situation with x=1 and y=1 such that deadlock occurs, we need not check the other 3 options. We can immediately claim that option D is our answer.
If the program P executes with only 1 thread T and 1 lock A, let's see what can happen. Using the property of non-reentrant locks as given in the problem, we find that if the thread T tries to acquire lock A twice without releasing lock A in between, deadlock will occur as T will block. So, option D is the right answer.
Answer: Option D
No comments:
Post a Comment