| |
Allocated |
Allocated |
Required |
Required |
| |
R1 |
R2 |
R1 |
R2 |
| P1 |
0 |
1 |
1 |
0 |
| P2 |
1 |
0 |
0 |
0 |
| P3 |
1 |
0 |
0 |
1 |
| p4 |
0 |
1 |
0 |
0 |
Here P1 requires R1 which is held by P3 which requires R2 which is held by P1.
P1 → R1 → P3 → R2 → P1, so cycle is there. But since P2 and P4 do not require any additional resource it will complete its execution and release its resource which then fulfill the requirement of P1 and P3. So deadlock is not there.
Answer : (D) Cycle but no deadlock.
Remember : In single instance resource allocation graph if there is a cycle there will be a deadlock, which is not true for multi-instance resource allocation graph.
