OS Dead Lock Avoidance C Program

Operating Systems Lab Manual / OS Dead Lock Avoidance C Program

Program Name	Write a C Program for Operating System Dead Lock Avoidance (Banker‘s Algorithm)
Theory	Deadlock is a situation in which two computer programs sharing the same resource are effectively preventing each other from accessing the resource, resulting in both programs ceasing to function. When a new process enters a system it declares the maximum number of instances of each resource type it needed which should not exceed the total number of resources in the system. The system always determines whether the allocation of each resources will leave the system in safe state for any user request a set of resources . If the resources are not allocated to the process at the moment the process has to wait until some other process release the resources used by it.
Program	#include<stdio.h> #include<string.h> void main() { int alloc[10][10],max[10][10]; int avail[10],work[10],total[10]; int i,j,k,n,need[10][10]; int m; int count=0,c=0; char finish[10]; printf("Enter Number of Processes and Resources:"); scanf("%d%d",&n,&m); for(i=0;i<=n;i++) finish[i]='n'; printf("Enter the Claim matrix:\n"); for(i=0;i<n;i++) for(j=0;j<m;j++) scanf("%d",&max[i][j]); printf("Enter the allocation matrix:\n"); for(i=0;i<n;i++) for(j=0;j<m;j++) scanf("%d",&alloc[i][j]); printf("Resource vector:"); for(i=0;i<m;i++) scanf("%d",&total[i]); for(i=0;i<m;i++) avail[i]=0; for(i=0;i<n;i++) for(j=0;j<m;j++) avail[j]+=alloc[i][j]; for(i=0;i<m;i++) work[i]=avail[i]; for(j=0;j<m;j++) work[j]=total[j]-work[j]; for(i=0;i<n;i++) for(j=0;j<m;j++) need[i][j]=max[i][j]-alloc[i][j]; A: for(i=0;i<n;i++) { c=0; for(j=0;j<m;j++) if((need[i][j]<=work[j])&&(finish[i]=='n')) c++; if(c==m) { printf("All the resources can be allocated to Process %d", i+1); printf("\n\nAvailable resources are:"); for(k=0;k<m;k++) { work[k]+=alloc[i][k]; printf("%4d",work[k]); } printf("\n"); finish[i]='y'; printf("\nProcess %d executed?:%c \n",i+1,finish[i]); count++; } } if(count!=n) goto A; else printf("\n System is in safe mode"); printf("\n The given state is safe state"); }
Input	Enter Number of Processes and Resources:4 3 Enter the Claim matrix: 3 3 2 2 6 1 3 3 1 4 4 2 2 Enter the allocation matrix: 1 0 0 6 1 2 2 1 1 0 0 2 Resource vector:9 3 6
Output	All the resources can be allocated to Process 2 Available resources are: 6 2 3 Process 2 executed?:y All the resources can be allocated to Process 3 Available resources are: 8 3 4 Process 3 executed?:y All the resources can be allocated to Process 4 Available resources are: 8 3 6 Process 4 executed?:y All the resources can be allocated to Process 1 Available resources are: 9 3 6 Process 1 executed?:y System is in safe mode The given state is safe state

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