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Deadlock Avoidance

Consider 3 co...

Question

Consider 3 concurrent processes X, Y & Z which request resources in the order given in options. There are total 5 resources $R_{1}$ to $R_{5}$ . If process do not get resource, it waits till it becomes available. Once process completes, it release all resources it has. Which of the following guarantees deadlock free operation?

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Solution

Option (A)

If all processes start concurrently. X can wait for $R_{5}$ which is taken by Z, Y wait for $R_{2}$ which is taken by X & Z waits for $R_{1}$
$∴$ Its a deadlock.
Option (B) & (D) also may lead to deadlock.
In option (C), the resource request sequence is in ordered sequence
$∴$ Its deadlock free.

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