Python页面置换算法代码

Python中，页面置换算法通常是用于操作系统或者内存管理方面的模拟。最常用的两个页面置换算法是简单淘汰（Least Recently Used, LRU）和先进先出（First In First Out, FIFO）。这里我会给出一个简单的LRU算法的伪代码示例，Python实现可能需要用到`collections`库中的`OrderedDict`：

from collections import OrderedDict

class Page ReplacementAlgorithm:
    def __init__(self, page_size):
        self.page_size = page_size
        self.free_pages = {}  # 使用OrderedDict记录已分配页
        self.lru_queue = []   # LRU队列

    def is_full(self):
        return len(self.free_pages) == 0

    def get_least_recently_used(self):
        if not self.lru_queue:
            return None
        return self.lru_queue.pop(0)

    def allocate_page(self, page_number):
        if self.is_full():
            lru_page = self.get_least_recently_used()
            if lru_page is not None:
                # 将被淘汰的页面从free_pages移除并加入lru_queue最后
                del self.free_pages[lru_page]
                self.lru_queue.append(lru_page)
            else:
                print("No free pages to replace.")
                return False
        self.free_pages[page_number] = (page_number, len(self.lru_queue))  # 更新最近使用时间
        self.lru_queue.append(page_number)
        return True

    def release_page(self, page_number):
        if page_number in self.free_pages:
            # 移除该页，保持LIFO顺序
            del self.free_pages[page_number]
            self.lru_queue.remove(page_number)
        else:
            print(f"Page {page_number} is not found.")

# 示例用法
alg = PageReplacementAlgorithm(page_size=4)
alg.allocate_page(1)
alg.allocate_page(2)
alg.release_page(1)
alg.release_page(3)

请注意，这只是一个简化的版本，实际生产环境中可能会有更复杂的数据结构和技术来处理并发请求、多进程等场景。