fcfs调度算法python实现

下面是一个使用 Python 实现 FCFS 调度算法的示例代码：

class Process:
    def __init__(self, pid, arrival_time, burst_time):
        self.pid = pid
        self.arrival_time = arrival_time
        self.burst_time = burst_time

def fcfs(processes):
    n = len(processes)
    waiting_time = [0] * n
    turnaround_time = [0] * n

    # 计算第一个进程的等待时间
    waiting_time[0] = 0

    # 计算每个进程的等待时间和周转时间
    for i in range(1, n):
        waiting_time[i] = processes[i-1].burst_time + waiting_time[i-1]
        turnaround_time[i-1] = waiting_time[i-1] + processes[i-1].burst_time

    # 计算最后一个进程的周转时间
    turnaround_time[n-1] = waiting_time[n-1] + processes[n-1].burst_time

    # 计算平均等待时间和平均周转时间
    avg_waiting_time = sum(waiting_time) / n
    avg_turnaround_time = sum(turnaround_time) / n

    # 打印每个进程的信息
    print("Process\tArrival Time\tBurst Time\tWaiting Time\tTurnaround Time")
    for i in range(n):
        print(f"{processes[i].pid}\t\t{processes[i].arrival_time}\t\t{processes[i].burst_time}\t\t{waiting_time[i]}\t\t{turnaround_time[i]}")

    # 打印平均等待时间和平均周转时间
    print(f"\nAverage waiting time: {avg_waiting_time:.2f}")
    print(f"Average turnaround time: {avg_turnaround_time:.2f}")

# 示例用法
if __name__ == "__main__":
    processes = [
        Process("P1", 0, 5),
        Process("P2", 1, 3),
        Process("P3", 2, 8),
        Process("P4", 3, 6)
    ]
    fcfs(processes)

输出结果如下：

Process	Arrival Time	Burst Time	Waiting Time	Turnaround Time
P1		0		5		0		5
P2		1		3		5		8
P3		2		8		8		16
P4		3		6		16		22

Average waiting time: 7.25
Average turnaround time: 12.75

其中，`Process` 类表示进程，包含进程 ID、到达时间和执行时间。`fcfs` 函数接受一个进程列表作为参数，计算每个进程的等待时间和周转时间，并输出结果。在示例中，我们创建了一个包含 4 个进程的列表，并将其作为参数传递给 `fcfs` 函数。