To write a C program to implement Bankers Algorithm.
1: Get the no of processes.
2: Get the process numbers.
3: Get the no of resources types and instances of it.
4: Get Max demand of each process of n x m matrices.
5: Get the n x m matrices the number of resources of each type currently allocated to each process.
6: Calculate the n x m of the remaining resource need of each process.
7: Initialize work as available resource and array of finish to false.
8: Check the Needed resource is lesser than the available resource if not display the System not in safe state and if it is lesser than system in safe state.
9: Initialize work as sum of work and allocation, check if array of finish is true go to step 7 again if not go to step 8.
10: Check that request can be immediately granted.
11: If single request is lesser than or equal to available if true means arrive to new state.
12: Print the sequence if it is in safe state or print not in safe state.
PROGRAM:
#include <stdio.h>
int main()
{
int n, m, i, j, k;
n = 5; // Number of processes
m = 3; //
int alloc[5][3] = { { 0, 1, 0 }, // P0 // Allocation Matrix
{ 2, 0, 0 }, // P1
{ 3, 0, 2 }, // P2
{ 2, 1, 1 }, // P3
{ 0, 0, 2 } }; // P4
int max[5][3] = { { 7, 5, 3 }, // P0 // MAX Matrix
{ 3, 2, 2 }, // P1
{ 9, 0, 2 }, // P2
{ 2, 2, 2 }, // P3
{ 4, 3, 3 } }; // P4
int avail[3] = { 3, 3, 2 }; // Available Resources
int f[n], ans[n], ind = 0;
for (k = 0; k < n; k++) {
f[k] = 0;
}
int need[n][m];
for (i = 0; i < n; i++) {
for (j = 0; j < m; j++)
need[i][j] = max[i][j] - alloc[i][j];
}
int y = 0;
for (k = 0; k < 5; k++) {
for (i = 0; i < n; i++) {
if (f[i] == 0) {
int flag = 0;
for (j = 0; j < m; j++) {
if (need[i][j] > avail[j]){
flag = 1;
break;
}
}
if (flag == 0) {
ans[ind++] = i;
for (y = 0; y < m; y++)
avail[y] += alloc[i][y];
f[i] = 1;
}
}
}
}
int flag = 1;
for(int i=0;i<n;i++)
{
if(f[i]==0)
{
flag=0;
printf("The following system is not safe");
break;
}
}
if(flag==1)
{
printf("Following is the SAFE Sequence\n");
for (i = 0; i < n - 1; i++)
printf(" P%d ->", ans[i]);
printf(" P%d", ans[n - 1]);
}
return (0);
}
Thus, implement Bankers Algorithm to avoid Deadlock is implemented successfully using C program.