BANKER'S AlGORITHM

Banker's Algorithm

Algorithm

1] Safety Algorithm:

Step 1- Let there be two vectors Work and Finish of length ‘m’ and ‘n’ in a safety algorithm.

Initialize: Work = Available

Finish(i) = False; for i = 0, 1, 2, 3, 4… n - 1.


Step 2- Check the availability status for each type of resources (i), such as:

Need(i) ≤ Work

Finish(i) == False

If the ‘i’ does not exist, go to step 4.


Step 3- Work = Work + Allocation(i) [to get new resource allocation]

Finish(i) = True

Go to step 2 to check the status of resource availability for the next process


Step 4- If Finish[i] == True; it means that the system is safe for all processes.


2] Resource Request Algorithm:

Let Request(i) be the request array for process P(i).

Request(i) [j] = k means process P(i) wants k instances of resource type R(i).

When a request for resources is made by process P[i], the following actions are taken:


Step 1- If Request(i) ≤ Need(i)

Go to Step 2; otherwise, raise an error condition, since the process has exceeded its maximum claim.


Step 2- If Request(i) ≤ Available

Go to Step 3; otherwise, P(i) must wait, since the resources are not available.


Step 3- When the requested resource is allocated to the process by changing state:

Available = Available – Request(i)

Allocation(i) = Allocation(i) + Request(i)

Need(i) = Need(i) – Request(i)