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shortest_job_first_preemptive_SRT.py
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shortest_job_first_preemptive_SRT.py
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class SJF:
def processData(self, no_of_processes):
process_data = []
for i in range(no_of_processes):
temporary = []
process_id = int(input("Enter Process ID: "))
arrival_time = float(input(f"Enter Arrival Time for Process {process_id}: "))
burst_time = float(input(f"Enter Burst Time for Process {process_id}: "))
temporary.extend([process_id, arrival_time, burst_time, 0, burst_time])
'''
'0' is the state of the process. 0 means not executed and 1 means execution complete
'''
process_data.append(temporary)
SJF.schedulingProcess(self, process_data)
def schedulingProcess(self, process_data):
start_time = []
exit_time = []
s_time = 0
sequence_of_process = []
process_data.sort(key=lambda x: x[1])
'''
Sort processes according to the Arrival Time
'''
while 1:
ready_queue = []
normal_queue = []
temp = []
for i in range(len(process_data)):
if process_data[i][1] <= s_time and process_data[i][3] == 0:
temp.extend([process_data[i][0], process_data[i][1], process_data[i][2], process_data[i][4]])
ready_queue.append(temp)
temp = []
elif process_data[i][3] == 0:
temp.extend([process_data[i][0], process_data[i][1], process_data[i][2], process_data[i][4]])
normal_queue.append(temp)
temp = []
if len(ready_queue) == 0 and len(normal_queue) == 0:
break
if len(ready_queue) != 0:
ready_queue.sort(key=lambda x: x[2])
'''
Sort processes according to Burst Time
'''
start_time.append(s_time)
s_time = s_time + 1
e_time = s_time
exit_time.append(e_time)
sequence_of_process.append(ready_queue[0][0])
for k in range(len(process_data)):
if process_data[k][0] == ready_queue[0][0]:
break
process_data[k][2] = process_data[k][2] - 1
if process_data[k][2] == 0: #If Burst Time of a process is 0, it means the process is completed
process_data[k][3] = 1
process_data[k].append(e_time)
if len(ready_queue) == 0:
if s_time < normal_queue[0][1]:
s_time = normal_queue[0][1]
start_time.append(s_time)
s_time = s_time + 1
e_time = s_time
exit_time.append(e_time)
sequence_of_process.append(normal_queue[0][0])
for k in range(len(process_data)):
if process_data[k][0] == normal_queue[0][0]:
break
process_data[k][2] = process_data[k][2] - 1
if process_data[k][2] == 0: #If Burst Time of a process is 0, it means the process is completed
process_data[k][3] = 1
process_data[k].append(e_time)
t_time = SJF.calculateTurnaroundTime(self, process_data)
w_time = SJF.calculateWaitingTime(self, process_data)
SJF.printData(self, process_data, t_time, w_time, sequence_of_process)
def calculateTurnaroundTime(self, process_data):
total_turnaround_time = 0
for i in range(len(process_data)):
turnaround_time = process_data[i][5] - process_data[i][1]
'''
turnaround_time = completion_time - arrival_time
'''
total_turnaround_time = total_turnaround_time + turnaround_time
process_data[i].append(turnaround_time)
average_turnaround_time = total_turnaround_time / len(process_data)
'''
average_turnaround_time = total_turnaround_time / no_of_processes
'''
return average_turnaround_time
def calculateWaitingTime(self, process_data):
total_waiting_time = 0
for i in range(len(process_data)):
waiting_time = process_data[i][6] - process_data[i][4]
'''
waiting_time = turnaround_time - burst_time
'''
total_waiting_time = total_waiting_time + waiting_time
process_data[i].append(waiting_time)
average_waiting_time = total_waiting_time / len(process_data)
'''
average_waiting_time = total_waiting_time / no_of_processes
'''
return average_waiting_time
def printData(self, process_data, average_turnaround_time, average_waiting_time, sequence_of_process):
process_data.sort(key=lambda x: x[0])
'''
Sort processes according to the Process ID
'''
print("Process_ID Arrival_Time Rem_Burst_Time Completed Orig_Burst_Time Completion_Time Turnaround_Time Waiting_Time")
for i in range(len(process_data)):
for j in range(len(process_data[i])):
print(process_data[i][j], end="\t\t")
print()
print(f'Average Turnaround Time: {average_turnaround_time}')
print(f'Average Waiting Time: {average_waiting_time}')
print(f'Sequence of Process: {sequence_of_process}')
if __name__ == "__main__":
no_of_processes = int(input("Enter number of processes: "))
sjf = SJF()
sjf.processData(no_of_processes)
'''
3
1
0
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.4
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1
1
'''