Python Implementation of Bankers Algorithm
Python Implementation of Banker's Algorithm
Description:
Banker's algorithm is a deadlock avoidance algorithm. It is named so because this algorithm is used in banking systems to determine whether a loan can be granted or not.Whenever a new process is created, it must exactly
specify the maximum instances of each resource type that it needs. The banker's algorithm is a method used in deadlock avoidance technique in multiple instances of a resource type.
The various data structures used in it are:
Let us assume that there are n processes and m resource types. Some data structures are used to implement the banker's algorithm. They are:
Available:
It is an array of length m. It represents the number of available resources of each type. If Available[j] = k, then there are k instances available, of resource type Rj.
Max: It is an n x m matrix which represents the maximum number of instances of each resource that a
process can request. If Max[i][j] = k, then the process Pi can request utmost k instances of resource type Rj.
Allocation: It is an n x m matrix which represents the number of resources of each type currently allocated to each process. If Allocation[i][j] = k, then process Pi is currently allocated k instances of resource type Rj.
Need:
It is an n x m matrix which indicates the remaining resource needs of each process. If Need[i][j] = k, then process Pi may need k more instances of resource type Rj to complete its task.
Need[i][j] = Max[i][j] - Allocation [i][j]
specify the maximum instances of each resource type that it needs. The banker's algorithm is a method used in deadlock avoidance technique in multiple instances of a resource type.
The various data structures used in it are:
Let us assume that there are n processes and m resource types. Some data structures are used to implement the banker's algorithm. They are:
Available:
It is an array of length m. It represents the number of available resources of each type. If Available[j] = k, then there are k instances available, of resource type Rj.
Max: It is an n x m matrix which represents the maximum number of instances of each resource that a
process can request. If Max[i][j] = k, then the process Pi can request utmost k instances of resource type Rj.
Allocation: It is an n x m matrix which represents the number of resources of each type currently allocated to each process. If Allocation[i][j] = k, then process Pi is currently allocated k instances of resource type Rj.
Need:
It is an n x m matrix which indicates the remaining resource needs of each process. If Need[i][j] = k, then process Pi may need k more instances of resource type Rj to complete its task.
Need[i][j] = Max[i][j] - Allocation [i][j]
Program :
def main():
processes = int(input("number of processes : "))
resources = int(input("number of resources : "))
max_resources = [int(i) for i in input("maximum resources : ").split()]
print("\n-- allocated resources for each process --")
currently_allocated = [[int(i) for i in input(f"process {j + 1} : ").split()] for j in range(processes)]
print("\n-- maximum resources for each process --")
max_need = [[int(i) for i in input(f"process {j + 1} : ").split()] for j in range(processes)]
allocated = [0] * resources
for i in range(processes):
for j in range(resources):
allocated[j] += currently_allocated[i][j]
print(f"\ntotal allocated resources : {allocated}")
available = [max_resources[i] - allocated[i] for i in range(resources)]
print(f"total available resources : {available}\n")
running = [True] * processes
count = processes
while count != 0:
safe = False
for i in range(processes):
if running[i]:
executing = True
for j in range(resources):
if max_need[i][j] - currently_allocated[i][j] > available[j]:
executing = False
break
if executing:
print(f"process {i + 1} is executing")
running[i] = False
count -= 1
safe = True
for j in range(resources):
available[j] += currently_allocated[i][j]
break
if not safe:
print("the processes are in an unsafe state.")
break
print(f"the process is in a safe state.\navailable resources : {available}\n")
if __name__ == '__main__':
main()
Output:
number of processes : 5
number of resources : 4
maximum resources : 8 5 9 7
-- allocated resources for each process --
process 1 : 2 0 1 1
process 2 : 0 1 2 1
process 3 : 4 0 0 3
process 4 : 0 2 1 0
process 5 : 1 0 3 0
-- maximum resources for each process --
process 1 : 3 2 1 4
process 2 : 0 2 5 2
process 3 : 5 1 0 5
process 4 : 1 5 3 0
process 5 : 3 0 3 3
total allocated resources : [7, 3, 7, 5]
total available resources : [1, 2, 2, 2]
process 3 is executing
the process is in a safe state.
available resources : [5, 2, 2, 5]
process 1 is executing
the process is in a safe state.
available resources : [7, 2, 3, 6]
process 2 is executing
the process is in a safe state.
available resources : [7, 3, 5, 7]
process 4 is executing
the process is in a safe state.
available resources : [7, 5, 6, 7]
process 5 is executing
the process is in a safe state.
available resources : [8, 5, 9, 7]
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