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Module 4: Deadlocks

20257m

Consider a system with five processes P0 through P4 and four resources type A, B, C and D. Using the Banker's algorithm answer that the system is in a safe state?

Process Allocation (A B C D) Max (A B C D) Available (A B C D)
P0 0 0 1 2 0 0 1 2 1 5 2 0
P1 1 0 0 0 1 7 5 0
P2 1 3 5 4 2 3 5 6
P3 0 6 3 2 0 6 5 2
P4 0 0 1 4 0 6 5 6
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Banker's Safe State Check (5 processes A-D)

Available 1,5,2,0. Need = Max-Alloc.
P0 Need 0,0,0,0 → can run, completes, releases 0,0,1,2 → Avail 1,5,3,2.
P3 Need 0,0,2,0 ≤ Avail → run → Avail 1,11,6,4.
P1 Need 0,7,5,0 ≤ Avail → run → Avail 2,11,6,4.
P2 Need 1,0,0,2 ≤ Avail → run → Avail 3,14,11,8.
P4 Need 0,6,4,2 ≤ Avail → finishes.
Safe sequence P0→P3→P1→P2→P4 exists, so system is safe.

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