短作业优先算法进程调度程序：Python示例与代码

{“title”: “选用短作业优先算法的进程调度程序”, “description”: “本文介绍了短作业优先算法 (SJF) 的概念，并提供了一个用 Python 实现的简单进程调度程序示例代码。该代码演示了如何在多道程序环境中模拟进程调度，并根据作业长度进行排序。”, “keywords”: “短作业优先算法, 进程调度, 进程调度程序, SJF, 多道程序, Python, 示例代码”, “content”: '这个程序首先会根据用户输入创建指定数量的进程，然后按照短作业优先算法进行调度，最后显示每个进程的状态。

请注意，这只是一个简单的示例，可能需要根据具体需求进行修改和扩展。

import time

class Process:
    def __init__(self, process_id, arrival_time, job_length, cpu_time, io_time):
        self.process_id = process_id
        self.arrival_time = arrival_time
        self.job_length = job_length
        self.cpu_time = cpu_time
        self.io_time = io_time
        self.state = “ready”  # 初始化进程状态为就备
        self.remaining_time = cpu_time  # 初始化剩余执行时间为CPU时间
        self.waiting_time = 0  # 初始化等待时间为0
    
    def run(self):
        self.state = “running”  # 将进程状态设置为执行
        time.sleep(self.remaining_time)  # 模拟进程执行
        self.remaining_time = 0  # 执行完毕后剩余执行时间为0
        self.state = “terminated”  # 将进程状态设置为结束
    
    def block(self):
        self.state = “blocked”  # 将进程状态设置为隔控
        time.sleep(self.io_time)  # 模拟I/O操作
        self.state = “ready”  # I/O操作完成后将进程状态设置为就备
    
    def __str__(self):
        return f“Process ID: {self.process_id}, Arrival Time: {self.arrival_time}, Job Length: {self.job_length}, CPU Time: {self.cpu_time}, I/O Time: {self.io_time}, State: {self.state}, Remaining Time: {self.remaining_time}, Waiting Time: {self.waiting_time}”

def create_processes(num_processes):
    processes = []
    for i in range(num_processes):
        process_id = i + 1
        arrival_time = int(input(f“Enter arrival time for process {process_id}: ”))
        job_length = int(input(f“Enter job length for process {process_id}: ”))
        cpu_time = int(input(f“Enter CPU time for process {process_id}: ”))
        io_time = int(input(f“Enter I/O time for process {process_id}: ”))
        process = Process(process_id, arrival_time, job_length, cpu_time, io_time)
        processes.append(process)
    return processes

def shortest_job_first(processes):
    time_elapsed = 0
    while processes:
        ready_processes = [process for process in processes if process.arrival_time <= time_elapsed and process.state == “ready”]
        if ready_processes:
            shortest_job = min(ready_processes, key=lambda process: process.job_length)
            shortest_job.waiting_time += time_elapsed - shortest_job.arrival_time  # 更新等待时间
            shortest_job.run()
            processes.remove(shortest_job)
            time_elapsed += shortest_job.cpu_time
            if shortest_job.job_length > shortest_job.cpu_time:  # 如果作业长度大于CPU时间，则隔控
                shortest_job.block()
                processes.append(shortest_job)
        else:
            time_elapsed += 1  # 没有就备进程时，时间流走

def display_processes(processes):
    for process in processes:
        print(process)

num_processes = int(input(“Enter the number of processes: ”))
processes = create_processes(num_processes)
shortest_job_first(processes)
display_processes(processes)

这个程序首先会根据用户输入创建指定数量的进程，然后按照短作业优先算法进行调度，最后显示每个进程的状态。

请注意，这只是一个简单的示例，可能需要根据具体需求进行修改和扩展。