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Program for Preemptive Priority CPU Scheduling

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Implementing priority CPU scheduling. In this problem, we are using Min Heap as the data structure for implementing priority scheduling. 

In this problem smaller numbers denote higher priority. 

The following functions are used in the given code below: 

struct process {
processID,
burst time,
response time,
priority,
arrival time.
}

  • void quicksort(process array[], low, high): This function is used to arrange the processes in ascending order according to their arrival time. 
  • int partition(process array[], int low, int high): This function is used to partition the array for sorting. 
  • void insert(process Heap[], process value, int *heapsize, int *currentTime): It is used to include all the valid and eligible processes in the heap for execution. heapsize defines the number of processes in execution depending on the current time currentTime keeps record of the current CPU time. 
  • void order(process Heap[], int *heapsize, int start): It is used to reorder the heap according to priority if the processes after insertion of new process. 
  • void extractminimum(process Heap[], int *heapsize, int *currentTime): This function is used to find the process with highest priority from the heap. It also reorders the heap after extracting the highest priority process. 
  • void scheduling(process Heap[], process array[], int n, int *heapsize, int *currentTime): This function is responsible for executing the highest priority extracted from Heap[]. 
  • void process(process array[], int n): This function is responsible for managing the entire execution of the processes as they arrive in the CPU according to their arrival time.

Implementation:

C++




// CPP program to implement preemptive priority scheduling
#include <bits/stdc++.h>
using namespace std;
 
struct Process {
    int processID;
    int burstTime;
    int tempburstTime;
    int responsetime;
    int arrivalTime;
    int priority;
    int outtime;
    int intime;
};
 
// It is used to include all the valid and eligible
// processes in the heap for execution. heapsize defines
// the number of processes in execution depending on
// the current time currentTime keeps a record of
// the current CPU time.
void insert(Process Heap[], Process value, int* heapsize,
            int* currentTime)
{
    int start = *heapsize, i;
    Heap[*heapsize] = value;
    if (Heap[*heapsize].intime == -1)
        Heap[*heapsize].intime = *currentTime;
    ++(*heapsize);
 
    // Ordering the Heap
    while (start != 0
           && Heap[(start - 1) / 2].priority
                  > Heap[start].priority) {
        Process temp = Heap[(start - 1) / 2];
        Heap[(start - 1) / 2] = Heap[start];
        Heap[start] = temp;
        start = (start - 1) / 2;
    }
}
 
// It is used to reorder the heap according to
// priority if the processes after insertion
// of new process.
void order(Process Heap[], int* heapsize, int start)
{
    int smallest = start;
    int left = 2 * start + 1;
    int right = 2 * start + 2;
    if (left < *heapsize
        && Heap[left].priority
               < Heap[smallest].priority)
        smallest = left;
    if (right < *heapsize
        && Heap[right].priority
               < Heap[smallest].priority)
        smallest = right;
 
    // Ordering the Heap
    if (smallest != start) {
        Process temp = Heap[smallest];
        Heap[smallest] = Heap[start];
        Heap[start] = temp;
        order(Heap, heapsize, smallest);
    }
}
 
// This function is used to find the process with
// highest priority from the heap. It also reorders
// the heap after extracting the highest priority process.
Process extractminimum(Process Heap[], int* heapsize,
                       int* currentTime)
{
    Process min = Heap[0];
    if (min.responsetime == -1)
        min.responsetime
            = *currentTime - min.arrivalTime;
    --(*heapsize);
    if (*heapsize >= 1) {
        Heap[0] = Heap[*heapsize];
        order(Heap, heapsize, 0);
    }
    return min;
}
 
// Compares two intervals
// according to starting times.
bool compare(Process p1, Process p2)
{
    return (p1.arrivalTime < p2.arrivalTime);
}
 
// This function is responsible for executing
// the highest priority extracted from Heap[].
void scheduling(Process Heap[], Process array[], int n,
                int* heapsize, int* currentTime)
{
    if (heapsize == 0)
        return;
 
    Process min = extractminimum(
        Heap, heapsize, currentTime);
    min.outtime = *currentTime + 1;
    --min.burstTime;
    printf("process id = %d current time = %d\n",
           min.processID, *currentTime);
 
    // If the process is not yet finished
    // insert it back into the Heap*/
    if (min.burstTime > 0) {
        insert(Heap, min, heapsize, currentTime);
        return;
    }
 
    for (int i = 0; i < n; i++)
        if (array[i].processID == min.processID) {
            array[i] = min;
            break;
        }
}
 
// This function is responsible for
// managing the entire execution of the
// processes as they arrive in the CPU
// according to their arrival time.
void priority(Process array[], int n)
{
    sort(array, array + n, compare);
 
    int totalwaitingtime = 0, totalbursttime = 0,
        totalturnaroundtime = 0, i, insertedprocess = 0,
        heapsize = 0, currentTime = array[0].arrivalTime,
        totalresponsetime = 0;
 
    Process Heap[4 * n];
 
    // Calculating the total burst time
    // of the processes
    for (int i = 0; i < n; i++) {
        totalbursttime += array[i].burstTime;
        array[i].tempburstTime = array[i].burstTime;
    }
 
    // Inserting the processes in Heap
    // according to arrival time
    do {
        if (insertedprocess != n) {
            for (i = 0; i < n; i++) {
                if (array[i].arrivalTime == currentTime) {
                    ++insertedprocess;
                    array[i].intime = -1;
                    array[i].responsetime = -1;
                    insert(Heap, array[i],
                           &heapsize, ¤tTime);
                }
            }
        }
        scheduling(Heap, array, n,
                   &heapsize, ¤tTime);
        ++currentTime;
        if (heapsize == 0
            && insertedprocess == n)
            break;
    } while (1);
 
    for (int i = 0; i < n; i++) {
        totalresponsetime
            += array[i].responsetime;
        totalwaitingtime
            += (array[i].outtime
                - array[i].intime
                - array[i].tempburstTime);
        totalbursttime += array[i].burstTime;
    }
    printf("Average waiting time = %f\n",
           ((float)totalwaitingtime / (float)n));
    printf("Average response time =%f\n",
           ((float)totalresponsetime / (float)n));
    printf("Average turn around time = %f\n",
           ((float)(totalwaitingtime
                    + totalbursttime)
            / (float)n));
}
 
// Driver code
int main()
{
    int n, i;
    Process a[5];
    a[0].processID = 1;
    a[0].arrivalTime = 4;
    a[0].priority = 2;
    a[0].burstTime = 6;
    a[1].processID = 4;
    a[1].arrivalTime = 5;
    a[1].priority = 1;
    a[1].burstTime = 3;
    a[2].processID = 2;
    a[2].arrivalTime = 5;
    a[2].priority = 3;
    a[2].burstTime = 1;
    a[3].processID = 3;
    a[3].arrivalTime = 1;
    a[3].priority = 4;
    a[3].burstTime = 2;
    a[4].processID = 5;
    a[4].arrivalTime = 3;
    a[4].priority = 5;
    a[4].burstTime = 4;
    priority(a, 5);
    return 0;
}


Java




import java.util.Arrays;
import java.util.Comparator;
 
class Process {
    int processID;
    int arrivalTime;
    int priority;
    int burstTime;
    int tempBurstTime;
    int responseTime;
    int outTime;
    int inTime;
 
    Process(int processID, int arrivalTime, int priority, int burstTime) {
        this.processID = processID;
        this.arrivalTime = arrivalTime;
        this.priority = priority;
        this.burstTime = burstTime;
        this.tempBurstTime = burstTime;
        this.responseTime = -1;
        this.outTime = 0;
        this.inTime = -1;
    }
}
 
public class PriorityScheduling {
    // Function to insert a process into the heap
    static void insert(Process[] heap, Process value, int[] heapSize, int[] currentTime) {
        int start = heapSize[0];
        heap[heapSize[0]] = value;
        if (heap[heapSize[0]].inTime == -1) {
            heap[heapSize[0]].inTime = currentTime[0];
        }
        heapSize[0]++;
 
        // Ordering the Heap
        while (start != 0 && heap[(start - 1) / 2].priority > heap[start].priority) {
            Process temp = heap[(start - 1) / 2];
            heap[(start - 1) / 2] = heap[start];
            heap[start] = temp;
            start = (start - 1) / 2;
        }
    }
 
    // Function to reorder the heap based on priority
    static void order(Process[] heap, int heapSize, int start) {
        int smallest = start;
        int left = 2 * start + 1;
        int right = 2 * start + 2;
        if (left < heapSize && heap[left].priority < heap[smallest].priority) {
            smallest = left;
        }
        if (right < heapSize && heap[right].priority < heap[smallest].priority) {
            smallest = right;
        }
 
        // Ordering the Heap
        if (smallest != start) {
            Process temp = heap[smallest];
            heap[smallest] = heap[start];
            heap[start] = temp;
            order(heap, heapSize, smallest);
        }
    }
 
    // Function to extract the process with the highest priority from the heap
    static Process extractMinimum(Process[] heap, int[] heapSize, int[] currentTime) {
        Process minProcess = heap[0];
        if (minProcess.responseTime == -1) {
            minProcess.responseTime = currentTime[0] - minProcess.arrivalTime;
        }
        heapSize[0]--;
        if (heapSize[0] >= 1) {
            heap[0] = heap[heapSize[0]];
            order(heap, heapSize[0], 0);
        }
        return minProcess;
    }
 
    // Function to compare two processes based on arrival time
    static boolean compare(Process p1, Process p2) {
        return p1.arrivalTime < p2.arrivalTime;
    }
 
    // Function responsible for executing the highest priority process extracted from the heap
    static void scheduling(Process[] heap, Process[] array, int n, int[] heapSize, int[] currentTime) {
        if (heapSize[0] == 0) {
            return;
        }
 
        Process minProcess = extractMinimum(heap, heapSize, currentTime);
        minProcess.outTime = currentTime[0] + 1;
        minProcess.burstTime--;
 
        System.out.println("process id = " + minProcess.processID + " current time = " + currentTime[0]);
 
        // If the process is not yet finished, insert it back into the Heap
        if (minProcess.burstTime > 0) {
            insert(heap, minProcess, heapSize, currentTime);
            return;
        }
 
        for (int i = 0; i < n; i++) {
            if (array[i].processID == minProcess.processID) {
                array[i] = minProcess;
                break;
            }
        }
    }
 
    // Function responsible for managing the entire execution of processes based on arrival time
    static void priority(Process[] array, int n) {
        Arrays.sort(array, Comparator.comparingInt(o -> o.arrivalTime));
 
        int totalWaitingTime = 0;
        int totalBurstTime = 0;
        int totalTurnaroundTime = 0;
        int insertedProcess = 0;
        int[] heapSize = {0};
        int[] currentTime = {array[0].arrivalTime};
        int totalResponseTime = 0;
 
        Process[] heap = new Process[4 * n];
 
        // Calculating the total burst time of the processes
        for (int i = 0; i < n; i++) {
            totalBurstTime += array[i].burstTime;
            array[i].tempBurstTime = array[i].burstTime;
        }
 
        // Inserting the processes into Heap according to arrival time
        do {
            if (insertedProcess != n) {
                for (int i = 0; i < n; i++) {
                    if (array[i].arrivalTime == currentTime[0]) {
                        insertedProcess++;
                        array[i].inTime = -1;
                        array[i].responseTime = -1;
                        insert(heap, array[i], heapSize, currentTime);
                    }
                }
            }
            scheduling(heap, array, n, heapSize, currentTime);
            currentTime[0]++;
            if (heapSize[0] == 0 && insertedProcess == n) {
                break;
            }
        } while (true);
 
        for (int i = 0; i < n; i++) {
            totalResponseTime += array[i].responseTime;
            totalWaitingTime += (array[i].outTime - array[i].inTime - array[i].tempBurstTime);
            totalTurnaroundTime += (array[i].outTime - array[i].inTime);
            totalBurstTime += array[i].burstTime;
        }
 
        System.out.println("Average waiting time = " + ((float) totalWaitingTime / n));
        System.out.println("Average response time = " + ((float) totalResponseTime / n));
        System.out.println("Average turn around time = " + ((float) (totalWaitingTime + totalBurstTime) / n));
    }
 
    // Driver code
    public static void main(String[] args) {
        int n = 5;
        Process[] a = {
                new Process(1, 4, 2, 6),
                new Process(4, 5, 1, 3),
                new Process(2, 5, 3, 1),
                new Process(3, 1, 4, 2),
                new Process(5, 3, 5, 4)
        };
 
        priority(a, n);
    }
}


Python3




class Process:
    def __init__(self, processID, arrivalTime, priority, burstTime):
        self.processID = processID
        self.arrivalTime = arrivalTime
        self.priority = priority
        self.burstTime = burstTime
        self.tempburstTime = burstTime
        self.responsetime = -1
        self.outtime = 0
        self.intime = -1
 
 
def insert(Heap, value, heapsize, currentTime):
    start = heapsize[0]
    Heap[heapsize[0]] = value
    if Heap[heapsize[0]].intime == -1:
        Heap[heapsize[0]].intime = currentTime[0]
    heapsize[0] += 1
 
    # Ordering the Heap
    while start != 0 and Heap[(start - 1) // 2].priority > Heap[start].priority:
        Heap[(start - 1) // 2], Heap[start] = Heap[start], Heap[(start - 1) // 2]
        start = (start - 1) // 2
 
 
def order(Heap, heapsize, start):
    smallest = start
    left = 2 * start + 1
    right = 2 * start + 2
    if left < heapsize[0] and Heap[left].priority < Heap[smallest].priority:
        smallest = left
    if right < heapsize[0] and Heap[right].priority < Heap[smallest].priority:
        smallest = right
 
    # Ordering the Heap
    if smallest != start:
        Heap[start], Heap[smallest] = Heap[smallest], Heap[start]
        order(Heap, heapsize, smallest)
 
 
def extract_minimum(Heap, heapsize, currentTime):
    min_process = Heap[0]
    if min_process.responsetime == -1:
        min_process.responsetime = currentTime[0] - min_process.arrivalTime
    heapsize[0] -= 1
    if heapsize[0] >= 1:
        Heap[0] = Heap[heapsize[0]]
        order(Heap, heapsize, 0)
    return min_process
 
 
def compare(p1, p2):
    return p1.arrivalTime < p2.arrivalTime
 
 
def scheduling(Heap, array, n, heapsize, currentTime):
    if heapsize[0] == 0:
        return
 
    min_process = extract_minimum(Heap, heapsize, currentTime)
    min_process.outtime = currentTime[0] + 1
    min_process.burstTime -= 1
    print(f"process id = {min_process.processID} current time = {currentTime[0]}")
 
    # If the process is not yet finished, insert it back into the Heap
    if min_process.burstTime > 0:
        insert(Heap, min_process, heapsize, currentTime)
        return
 
    for i in range(n):
        if array[i].processID == min_process.processID:
            array[i] = min_process
            break
 
 
def priority(array, n):
    array.sort(key=lambda x: x.arrivalTime)
 
    total_waiting_time = 0
    total_burst_time = 0
    total_turnaround_time = 0
    inserted_process = 0
    heap_size = [0]
    current_time = [array[0].arrivalTime]
    total_response_time = 0
 
    Heap = [None] * (4 * n)
 
    # Calculating the total burst time of the processes
    for i in range(n):
        total_burst_time += array[i].burstTime
        array[i].tempburstTime = array[i].burstTime
 
    # Inserting the processes in Heap according to arrival time
    while True:
        if inserted_process != n:
            for i in range(n):
                if array[i].arrivalTime == current_time[0]:
                    inserted_process += 1
                    array[i].intime = -1
                    array[i].responsetime = -1
                    insert(Heap, array[i], heap_size, current_time)
        scheduling(Heap, array, n, heap_size, current_time)
        current_time[0] += 1
        if heap_size[0] == 0 and inserted_process == n:
            break
 
    for i in range(n):
        total_response_time += array[i].responsetime
        total_waiting_time += (array[i].outtime - array[i].intime - array[i].tempburstTime)
        total_turnaround_time += (array[i].outtime - array[i].intime)
        total_burst_time += array[i].burstTime
 
    print(f"Average waiting time = {total_waiting_time / n}")
    print(f"Average response time = {total_response_time / n}")
    print(f"Average turn around time = {total_turnaround_time / n}")
 
 
# Driver code
if __name__ == "__main__":
    n = 5
    a = [
        Process(1, 4, 2, 6),
        Process(4, 5, 1, 3),
        Process(2, 5, 3, 1),
        Process(3, 1, 4, 2),
        Process(5, 3, 5, 4)
    ]
    priority(a, n)


C#




using System;
using System.Collections.Generic;
using System.Linq;
 
class Process
{
    public int ProcessID { get; set; }
    public int ArrivalTime { get; set; }
    public int Priority { get; set; }
    public int BurstTime { get; set; }
    public int TempBurstTime { get; set; }
    public int ResponseTime { get; set; } = -1;
    public int OutTime { get; set; }
    public int InTime { get; set; } = -1;
 
    // Constructor to initialize a Process object
    public Process(int processID, int arrivalTime, int priority, int burstTime)
    {
        ProcessID = processID;
        ArrivalTime = arrivalTime;
        Priority = priority;
        BurstTime = burstTime;
        TempBurstTime = burstTime;
    }
}
 
class Program
{
    // Function to insert a process into the heap
    static void Insert(List<Process> heap, Process value, ref int heapSize, ref int currentTime)
    {
        int start = heapSize;
        heap.Add(value);
        if (heap[heapSize].InTime == -1)
            heap[heapSize].InTime = currentTime;
        heapSize++;
 
        // Ordering the Heap
        while (start != 0 && heap[(start - 1) / 2].Priority > heap[start].Priority)
        {
            Process temp = heap[(start - 1) / 2];
            heap[(start - 1) / 2] = heap[start];
            heap[start] = temp;
            start = (start - 1) / 2;
        }
    }
 
    // Function to reorder the heap based on priority
    static void Order(List<Process> heap, int heapSize, int start)
    {
        int smallest = start;
        int left = 2 * start + 1;
        int right = 2 * start + 2;
        if (left < heapSize && heap[left].Priority < heap[smallest].Priority)
            smallest = left;
        if (right < heapSize && heap[right].Priority < heap[smallest].Priority)
            smallest = right;
 
        // Ordering the Heap
        if (smallest != start)
        {
            Process temp = heap[smallest];
            heap[smallest] = heap[start];
            heap[start] = temp;
            Order(heap, heapSize, smallest);
        }
    }
 
    // Function to extract the process with the highest priority from the heap
    static Process ExtractMinimum(List<Process> heap, ref int heapSize, ref int currentTime)
    {
        Process minProcess = heap[0];
        if (minProcess.ResponseTime == -1)
            minProcess.ResponseTime = currentTime - minProcess.ArrivalTime;
        heapSize--;
        if (heapSize >= 1)
        {
            heap[0] = heap[heapSize];
            Order(heap, heapSize, 0);
        }
        return minProcess;
    }
 
    // Function to compare two processes based on arrival time
    static bool Compare(Process p1, Process p2)
    {
        return p1.ArrivalTime < p2.ArrivalTime;
    }
 
    // Function responsible for executing the highest priority process extracted from the heap
    static void Scheduling(List<Process> heap, List<Process> array, int n, ref int heapSize, ref int currentTime)
    {
        if (heapSize == 0)
            return;
 
        Process minProcess = ExtractMinimum(heap, ref heapSize, ref currentTime);
        minProcess.OutTime = currentTime + 1;
        minProcess.BurstTime--;
 
        Console.WriteLine($"process id = {minProcess.ProcessID} current time = {currentTime}");
 
        // If the process is not yet finished, insert it back into the Heap
        if (minProcess.BurstTime > 0)
        {
            Insert(heap, minProcess, ref heapSize, ref currentTime);
            return;
        }
 
        for (int i = 0; i < n; i++)
        {
            if (array[i].ProcessID == minProcess.ProcessID)
            {
                array[i] = minProcess;
                break;
            }
        }
    }
 
    // Function responsible for managing the entire execution of processes based on arrival time
    static void Priority(List<Process> array, int n)
    {
        array = array.OrderBy(p => p.ArrivalTime).ToList();
 
        int totalWaitingTime = 0;
        int totalBurstTime = 0;
        int totalTurnaroundTime = 0;
        int insertedProcess = 0;
        int heapSize = 0;
        int currentTime = array[0].ArrivalTime;
        int totalResponseTime = 0;
 
        List<Process> heap = new List<Process>(4 * n);
 
        // Calculating the total burst time of the processes
        for (int i = 0; i < n; i++)
        {
            totalBurstTime += array[i].BurstTime;
            array[i].TempBurstTime = array[i].BurstTime;
        }
 
        // Inserting the processes in Heap according to arrival time
        do
        {
            if (insertedProcess != n)
            {
                for (int i = 0; i < n; i++)
                {
                    if (array[i].ArrivalTime == currentTime)
                    {
                        insertedProcess++;
                        array[i].InTime = -1;
                        array[i].ResponseTime = -1;
                        Insert(heap, array[i], ref heapSize, ref currentTime);
                    }
                }
            }
            Scheduling(heap, array, n, ref heapSize, ref currentTime);
            currentTime++;
            if (heapSize == 0 && insertedProcess == n)
                break;
        } while (true);
 
        for (int i = 0; i < n; i++)
        {
            totalResponseTime += array[i].ResponseTime;
            totalWaitingTime += (array[i].OutTime - array[i].InTime - array[i].TempBurstTime);
            totalTurnaroundTime += (array[i].OutTime - array[i].InTime);
            totalBurstTime += array[i].BurstTime;
        }
 
        Console.WriteLine($"Average waiting time = {totalWaitingTime / (float)n}");
        Console.WriteLine($"Average response time = {totalResponseTime / (float)n}");
        Console.WriteLine($"Average turn around time = {totalTurnaroundTime / (float)n}");
    }
 
    static void Main(string[] args)
    {
        int n = 5;
        List<Process> a = new List<Process>
        {
            new Process(1, 4, 2, 6),
            new Process(4, 5, 1, 3),
            new Process(2, 5, 3, 1),
            new Process(3, 1, 4, 2),
            new Process(5, 3, 5, 4)
        };
 
        Priority(a, n);
    }
}


Javascript




class Process {
    constructor(processID, arrivalTime, priority, burstTime) {
        this.ProcessID = processID;
        this.ArrivalTime = arrivalTime;
        this.Priority = priority;
        this.BurstTime = burstTime;
        this.TempBurstTime = burstTime;
        this.ResponseTime = -1;
        this.OutTime = 0;
        this.InTime = -1;
    }
}
 
// Function to insert a process into the heap
function Insert(heap, value, heapSize, currentTime) {
    let start = heapSize[0];
    heap[start] = value;
    if (heap[start].InTime === -1) {
        heap[start].InTime = currentTime[0];
    }
    heapSize[0]++;
 
    // Ordering the Heap
    while (start !== 0 && heap[Math.floor((start - 1) / 2)].Priority > heap[start].Priority) {
        [heap[Math.floor((start - 1) / 2)], heap[start]] = [heap[start], heap[Math.floor((start - 1) / 2)]];
        start = Math.floor((start - 1) / 2);
    }
}
 
// Function to reorder the heap based on priority
function Order(heap, heapSize, start) {
    let smallest = start;
    let left = 2 * start + 1;
    let right = 2 * start + 2;
    if (left < heapSize[0] && heap[left].Priority < heap[smallest].Priority) {
        smallest = left;
    }
    if (right < heapSize[0] && heap[right].Priority < heap[smallest].Priority) {
        smallest = right;
    }
 
    // Ordering the Heap
    if (smallest !== start) {
        [heap[start], heap[smallest]] = [heap[smallest], heap[start]];
        Order(heap, heapSize, smallest);
    }
}
 
// Function to extract the process with the highest priority from the heap
function ExtractMinimum(heap, heapSize, currentTime) {
    let minProcess = heap[0];
    if (minProcess.ResponseTime === -1) {
        minProcess.ResponseTime = currentTime[0] - minProcess.ArrivalTime;
    }
    heapSize[0]--;
    if (heapSize[0] >= 1) {
        heap[0] = heap[heapSize[0]];
        Order(heap, heapSize, 0);
    }
    return minProcess;
}
 
// Function to compare two processes based on arrival time
function Compare(p1, p2) {
    return p1.ArrivalTime < p2.ArrivalTime;
}
 
// Function responsible for executing the highest priority process extracted from the heap
function Scheduling(heap, array, n, heapSize, currentTime) {
    if (heapSize[0] === 0) {
        return;
    }
 
    let minProcess = ExtractMinimum(heap, heapSize, currentTime);
    minProcess.OutTime = currentTime[0] + 1;
    minProcess.BurstTime--;
 
    console.log(`process id = ${minProcess.ProcessID} current time = ${currentTime[0]}`);
 
    // If the process is not yet finished, insert it back into the Heap
    if (minProcess.BurstTime > 0) {
        Insert(heap, minProcess, heapSize, currentTime);
        return;
    }
 
    for (let i = 0; i < n; i++) {
        if (array[i].ProcessID === minProcess.ProcessID) {
            array[i] = minProcess;
            break;
        }
    }
}
 
// Function responsible for managing the entire execution of processes based on arrival time
function Priority(array, n) {
    array.sort((p1, p2) => p1.ArrivalTime - p2.ArrivalTime);
 
    let totalWaitingTime = 0;
    let totalBurstTime = 0;
    let totalTurnaroundTime = 0;
    let insertedProcess = 0;
    let heapSize = [0];
    let currentTime = [array[0].ArrivalTime];
    let totalResponseTime = 0;
 
    let heap = Array(4 * n);
 
    // Calculating the total burst time of the processes
    for (let i = 0; i < n; i++) {
        totalBurstTime += array[i].BurstTime;
        array[i].TempBurstTime = array[i].BurstTime;
    }
 
    // Inserting the processes into Heap according to arrival time
    do {
        if (insertedProcess !== n) {
            for (let i = 0; i < n; i++) {
                if (array[i].ArrivalTime === currentTime[0]) {
                    insertedProcess++;
                    array[i].InTime = -1;
                    array[i].ResponseTime = -1;
                    Insert(heap, array[i], heapSize, currentTime);
                }
            }
        }
        Scheduling(heap, array, n, heapSize, currentTime);
        currentTime[0]++;
        if (heapSize[0] === 0 && insertedProcess === n) {
            break;
        }
    } while (true);
 
    for (let i = 0; i < n; i++) {
        totalResponseTime += array[i].ResponseTime;
        totalWaitingTime += (array[i].OutTime - array[i].InTime - array[i].TempBurstTime);
        totalTurnaroundTime += (array[i].OutTime - array[i].InTime);
        totalBurstTime += array[i].BurstTime;
    }
 
    console.log(`Average waiting time = ${totalWaitingTime / n}`);
    console.log(`Average response time = ${totalResponseTime / n}`);
    console.log(`Average turn around time = ${totalTurnaroundTime / n}`);
}
 
// Driver code
let n = 5;
let a = [
    new Process(1, 4, 2, 6),
    new Process(4, 5, 1, 3),
    new Process(2, 5, 3, 1),
    new Process(3, 1, 4, 2),
    new Process(5, 3, 5, 4)
];
 
Priority(a, n);
//This code is contributed by Kishan


Output

process id = 3 current time = 1
process id = 3 current time = 2
process id = 5 current time = 3
process id = 1 current time = 4
process id = 4 current time = 5
process id = 4 current time = 6
process id = 4 current time = 7
process id = 1 current time = 8
process id = 1 current time = 9
process id = 1 current time = 10
process id = 1 current time = 11
process id = 1 current time = 12
process id = 2 current time = 13
process id = 5 current time = 14
process id = 5 current time = 15
process id = 5 current time = 16
Average waiting time = 4.200000
Average response time =1.600000
Average turn around time = 7.400000







The output displays the order in which the processes are executed in the memory and also shows the average waiting time, average response time and average turn around time for each process.

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Last Updated : 24 Feb, 2024
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