What is claim vector in banker's algorithm?

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.

Consider there are n account holders in a bank and the sum of the money in all of their accounts is S. Every time a loan has to be granted by the bank, it subtracts the loan amount from the total money the bank has. Then it checks if that difference is greater than S. It is done because, only then, the bank would have enough money even if all the n account holders draw all their money at once.

Banker's algorithm works in a similar way in computers.

Â

Â

The characteristics of Banker's algorithm are as follows:

Let us assume that there are n processes and m resource types.

Some data structures that are used to implement the banker's algorithm are:

It is an array of length m. It represents the number of available resources of each type. If Available = k, then there are k instances available, of resource type Rj.

It is an n x m matrix which represents the maximum number of instances of each resource that a process can request. If Max = k, then the process Pi can request atmost k instances of resource type Rj.

It is an n x m matrix which represents the number of resources of each type currently allocated to each process. If Allocation = k, then process Pi is currently allocated k instances of resource type Rj.

It is a two-dimensional array. It is an n x m matrix which indicates the remaining resource needs of each process. If Need = k, then process Pi may need k more instances of resource type Rj to complete its task.

A safety algorithm is an algorithm used to find whether or not a system is in its safe state. The algorithm is as follows:

This algorithm may require an order of mxn² operations in order to determine whether a state is safe or not.

Now the next algorithm is a resource-request algorithm and it is mainly used to determine whether requests can be safely granted or not.

Let Requesti be the request vector for the process Pi. If Requesti==k, then process Pi wants k instance of Resource type Rj.When a request for resources is made by the process Pi, the following are the actions that will be taken:

1. If Requesti <= Needi, then go to step 2;else raise an error condition, since the process has exceeded its maximum claim.

2.If Requesti <= Availablei then go to step 3; else Pi must have to wait as resources are not available.

3.Now we will assume that resources are assigned to process Pi and thus perform the following steps:

Available= Available-Requesti;

Allocationi=Allocationi +Requesti;

Needi =Needi - Requesti;

If the resulting resource allocation state comes out to be safe, then the transaction is completed and, process Pi is allocated its resources. But in this case, if the new state is unsafe, then Pi waits for Requesti, and the old resource-allocation state is restored.

Some disadvantages of this algorithm are as follows:

Now its time to take a look at the Example of Banker's Algorithm:

Example:

Let us consider the following snapshot for understanding the banker's algorithm:

Solution:

1. The Content of the need matrix can be calculated by using the formula given below:

Need = Max – Allocation

2. Let us now check for the safe state.

Safe sequence:

Available = (2, 1, 0)

Need <=Available = False

So, the system will move to the next process.

2. For Process P1, Need = (1, 1, 0)

Available = (2, 1, 0)

Need <= Available = True

Request of P1 is granted.

Available = Available +Allocation

= (2, 1, 0) + (2, 1, 2)

= (4, 2, 2) (New Available)

3. For Process P2, Need = (5, 0, 1)

Available = (4, 2, 2)

Need <=Available = False

So, the system will move to the next process.

4. For Process P3, Need = (7, 3, 3)

Available = (4, 2, 2)

Need <=Available = False

So, the system will move to the next process.

5. For Process P4, Need = (0, 0, 0)

Available = (4, 2, 2)

Need <= Available = True

Request of P4 is granted.

Available = Available + Allocation

= (4, 2, 2) + (1, 1, 2)

= (5, 3, 4) now, (New Available)

6. Now again check for Process P2, Need = (5, 0, 1)

Available = (5, 3, 4)

Need <= Available = True

Request of P2 is granted.

Available = Available + Allocation

= (5, 3, 4) + (4, 0, 1)

= (9, 3, 5) now, (New Available)

7. Now again check for Process P3, Need = (7, 3, 3)

Available = (9, 3, 5)

Need <=Available = True

The request for P3 is granted.

Available = Available +Allocation

= (9, 3, 5) + (0, 2, 0) = (9, 5, 5)

8. Now again check for Process P0, = Need (3, 2, 1)

= Available (9, 5, 5)

Need <= Available = True

So, the request will be granted to P0.

Safe sequence: < P1, P4, P2, P3, P0>

The system allocates all the needed resources to each process. So, we can say that the system is in a safe state.

3. The total amount of resources will be calculated by the following formula:

The total amount of resources= sum of columns of allocation + Available

= + =

Given below is the code for Banker's algorithm implementation:

Here is the output of the above program:

With this we end the banker's algorithm tutorial. We hope you understood it, if not go to our forum and ask your doubt.

The banker's algorithm is a resource allocation and deadlock avoidance algorithm that tests for safety by simulating the allocation for predetermined maximum possible amounts of all resources, then makes an “s-state” check to test for possible activities, before deciding whether allocation should be allowed to continue

The Banker algorithm, sometimes referred to as the detection algorithm, is a resource allocation available_resources = [int(x) for x in input('Claim vector?

Banker's Algorithm is a resource allocation and deadlock avoidance algorithm. Available vector; Max Matrix; Allocation Matrix; Need Matrix.

The Banker's algorithm is a resource allocation and deadlock avoidance algorithm developed by Edsger printf("\nThe Claim Vector is: ");"C · Go · Julia · Kotlin

Here you will get program for banker's algorithm in C. The banker's Available: A vector of length m. It shows printf("\nThe Claim Vector is: ");. for (i = 0; i

What is Banker's Algorithm? Banker's Algorithm is used majorly in the banking system to avoid deadlock. It helps you to identify whether a loan

The banker’s algorithm is a resource allocation and deadlock avoidance algorithm that tests for safety by simulating the allocation for the predetermined maximum possible amounts of all resources, then makes an “s-state” check to test for possible activities, before deciding whether allocation should be allowed to continue.

Banker’s algorithm is named so because it is used in the banking system to check whether a loan can be sanctioned to a person or not. Suppose there are n number of account holders in a bank and the total sum of their money is S. If a person applies for a loan then the bank first subtracts the loan amount from the total money that the bank has and if the remaining amount is greater than S then only the loan is sanctioned. It is done because if all the account holders come to withdraw their money then the bank can easily do it.

In other words, the bank would never allocate its money in such a way that it can no longer satisfy the needs of all its customers. The bank would try to be in a safe state always.

The following Data structures are used to implement the Banker’s Algorithm:Let ‘n’ be the number of processes in the system and ‘m’ be the number of resource types.Available :

Max :

Allocation :

Need :

Allocation specifies the resources currently allocated to process Pi and Needi specifies the additional resources that process Pi may still request to complete its task.Banker’s algorithm consists of a Safety algorithm and a Resource request algorithm.

The algorithm for finding out whether or not a system is in a safe state can be described as follows:

Resource-Request AlgorithmLet Requesti be the request array for process Pi. Requesti = k means process Pi wants k instances of resource type Rj. When a request for resources is made by process Pi, the following actions are taken:

Example:Considering a system with five processes P0 through P4 and three resources of type A, B, C. Resource type A has 10 instances, B has 5 instances and type C has 7 instances. Suppose at time t0 following snapshot of the system has been taken:

Question1. What will be the content of the Need matrix?Need = Max – Allocation So, the content of Need Matrix is:

Question2.  Is the system in a safe state? If Yes, then what is the safe sequence?Applying the Safety algorithm on the given system,

Question3. What will happen if process P1 requests one additional instance of resource type A and two instances of resource type C?

We must determine whether this new system state is safe. To do so, we again execute Safety algorithm on the above data structures.

Hence the new system state is safe, so we can immediately grant the request for process  P1 .Code for Banker’s Algorithm

The maximum claim (or maximum demands) of each process. The Avail vector is [0 5 7]. Algorithm for deadlock avoidance (Banker's algorithm): The