A computer operating system is a system administrator at the software level that coordinates the interaction between computer hardware and applications. A deep understanding of the basic concepts of an operating system is essential for designing efficient, reliable software. This article will delve into the core concepts of computer operating systems, covering processes and threads, memory management, file systems, device management, process scheduling, and deadlocks.
A process is an instance of program execution with an independent memory space and execution environment. The operating system implements reasonable allocation and isolation of system resources through process management. Explain in detail the lifecycle of a process, including create, wait, and terminate.
Example: Create a process using the multiprocessing module of Python.
import multiprocessing
def worker():
print("worker process")
if __name__ == "__main__":
process = multiprocessing.process(target=worker)
process.start()
process.join()
Example: Create a thread using the Python threading module.
import threading
def print_numbers():
for i in range(5):
print(i)
def print_letters():
for letter in 'abcde':
print(letter)
if __name__ == "__main__":
t1 = threading.thread(target=print_numbers)
t2 = threading.thread(target=print_letters)
t1.start()
t2.start()
t1.join()
t2.join()
Example: Memory allocation and release in C.
#include
int main()
int *array = (int *)malloc(5 * sizeof(int));
Use array
free(array);
return 0;
Example: Python implementation of the LRU algorithm.
from collections import ordereddict
class lrucache:
def __init__(self, capacity):
self.cache = ordereddict()
self.capacity = capacity
def get(self, key):
if key in self.cache:
self.cache.move_to_end(key)
return self.cache[key]
return -1
def put(self, key, value):
if key in self.cache:
del self.cache[key]
elif len(self.cache) >= self.capacity:
self.cache.popitem(last=false)
self.cache[key] = value
Example: File operations in C.
#include
int main()
file *file = fopen("example.txt", "w");
fprintf(file, "hello, world!");
fclose(file);
return 0;
Example**: File permission settings in Linux.
chmod 755 example.sh
Example**: Simple IO operation in C.
#include
int main()
char c;
printf("enter a character: ");
scanf("%c", &c);
printf("you entered: %c", c);
return 0;
;Example: Interrupt handling in assembly language.
interrupt_handler:
Interrupt Handling**.
ret
Example: A simple time-slice rotation scheduling algorithm.
def round_robin_scheduling(processes, burst_time, quantum):
n = len(processes)
remaining_burst_time = list(burst_time)
waiting_time, turnaround_time = [0] *n, [0] *n
time = 0
while true:
all_finished = true
for i in range(n):
if remaining_burst_time[i] >0:
all_finished = false
if remaining_burst_time[i] >quantum:
time += quantum
remaining_burst_time[i] -= quantum
else:time += remaining_burst_time[i]
waiting_time[i] = time - burst_time[i]
remaining_burst_time[i] = 0
if all_finished:
breakfor i in range(n):
turnaround_time[i] = burst_time[i] +waiting_time[i]
return waiting_time, turnaround_time
This article provides an in-depth look at the basic concepts of computer operating systems, including processes and threads, memory management, file systems, device management, and more. These concepts are an indispensable foundation in computer science and software engineering, laying a solid foundation for designing efficient and stable software.