GATE | GATE-CS-2009 | Question 60
Consider a system with 4 types of resources R1 (3 units), R2 (2 units), R3 (3 units), R4 (2 units). A non-preemptive resource allocation policy is used. At any given instance, a request is not entertained if it cannot be completely satisfied. Three processes P1, P2, P3 request the sources as follows if executed independently.
Process P1: t=0: requests 2 units of R2 t=1: requests 1 unit of R3 t=3: requests 2 units of R1 t=5: releases 1 unit of R2 and 1 unit of R1. t=7: releases 1 unit of R3 t=8: requests 2 units of R4 t=10: Finishes Process P2: t=0: requests 2 units of R3 t=2: requests 1 unit of R4 t=4: requests 1 unit of R1 t=6: releases 1 unit of R3 t=8: Finishes Process P3: t=0: requests 1 unit of R4 t=2: requests 2 units of R1 t=5: releases 2 units of R1 t=7: requests 1 unit of R2 t=8: requests 1 unit of R3 t=9: Finishes
Which one of the following statements is TRUE if all three processes run concurrently starting at time t=0?
(A) All processes will finish without any deadlock
(B) Only P1 and P2 will be in deadlock.
(C) Only P1 and P3 will be in a deadlock.
(D) All three processes will be in deadlock
We can apply the following Deadlock Detection algorithm and see that there is no process waiting indefinitely for a resource. See this for deadlock detection algorithm.