Consider a system with seven processes A through G and six resources R through W. Resource ownership is as follows :
Consider a system with seven processes A through G and six resources R through W. Resource ownership is as follows :
process A holds R and wants T
process B holds nothing but wants T
process C holds nothing but wants S
process D holds U and wants S & T
process E holds T and wants S
process F holds W and wants S
process G holds V and wants U
Is the system deadlocked? If yes, ............... processes are deadlocked.
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Correct answer: (C) Yes, D, E, G
Explanation
Note: the original exam reads "process E holds T and wants V"; as printed (E wants S, which no process holds) there would be no cycle, but the key assumes the original wording. In the resource allocation graph there is a cycle D → T → E → V → G → U → D (D waits for T held by E, E waits for V held by G, G waits for U held by D). So the system is deadlocked and processes D, E and G are deadlocked. Answer is option (c).