Python實現哲學家就餐問題

哲學家就餐問題是典型的同步問題，該問題描述的是五個哲學家共用一張圓桌，分別坐在五張椅子上，在圓桌上有五個盤子和五個叉子（如下圖），他們的生活方式是交替的進行思考和進餐，思考時不能用餐，用餐時不能思考。平時，乙個哲學家進行思考，飢餓時便試圖用餐，只有在他同時拿到他的盤子左右兩邊的兩個叉子時才能進餐。進餐完畢後，他會放下叉子繼續思考。請寫出**來解決如上的哲學家就餐問題，要求**返回「當每個哲學家分別需要進食 n 次」時這五位哲學家具體的行為記錄。

輸入：n = 1 （1<=n<=60，n 表示每個哲學家需要進餐的次數。）

[[4,2,1],[4,1,1],[0,1,1],[2,2,1],[2,1,1],[2,0,3],[2,1,2],[2,2,2],[4,0,3],[4,1,2],[0,2,1],[4,2,2],[3,2,1],[3,1,1],[0,0,3],[0,1,2],[0,2,2],[1,2,1],[1,1,1],[3,0,3],[3,1,2],[3,2,2],[1,0,3],[1,1,2],[1,2,2]]

輸出列表中的每乙個子列表描述了某個哲學家的具體行為，它的格式如下：

output[i] = [a, b, c] (3 個整數)

import queue
import threading
import time
import random
class countdownlatch:
def __init__(self, count):
self.count = count
self.condition = threading.condition()
def wait(self):
try:
self.condition.acquire()
while self.count > 0:
self.condition.wait()
finally:
self.condition.release()
def count_down(self):
try:
self.condition.acquire()
self.count -= 1
self.condition.notifyall()
finally:
self.condition.release()
class diningphilosophers(threading.thread):
def __init__(self, philosopher_number, left_fork, right_fork, operate_queue, count_latch):
super().__init__()
self.philosopher_number = philosopher_number
self.left_fork = left_fork
self.right_fork = right_fork
self.operate_queue = operate_queue
self.count_latch = count_latch
def eat(self):
time.sleep(0.01)
self.operate_queue.put([self.philosopher_number, 0, 3])
def think(self):
time.sleep(random.random())
def pick_left_fork(self):
self.operate_queue.put([self.philosopher_number, 1, 1])
def pick_right_fork(self):
self.operate_queue.put([self.philosopher_number, 2, 1])
def put_left_fork(self):
self.left_fork.release()
self.operate_queue.put([self.philosopher_number, 1, 2])
def put_right_fork(self):
self.right_fork.release()
self.operate_queue.put([self.philosopher_number, 2, 2])
def run(self):
while true:
left = self.left_fork.acquire(blocking=false)
right = self.right_fork.acquire(blocking=false)
if left and right:
self.pick_left_fork()
self.pick_right_fork()
self.eat()
self.put_left_fork()
self.put_right_fork()
break
elif left and not right:
self.left_fork.release()
elif right and not left:
self.right_fork.release()
else:
time.sleep(0.01)
print(str(self.philosopher_number) + ' count_down')
self.count_latch.count_down()
if __name__ == '__main__':
operate_queue = queue.queue()
fork1 = threading.lock()
fork2 = threading.lock()
fork3 = threading.lock()
fork4 = threading.lock()
fork5 = threading.lock()
n = 1
latch = countdownlatch(5 * n)
for _ in range(n):
philosopher0 = diningphilosophers(0, fork5, fork1, operate_queue, latch)
philosopher0.start()
philosopher1 = diningphilosophers(1, fork1, fork2, operate_queue, latch)
philosopher1.start()
philosopher2 = diningphilosophers(2, fork2, fork3, operate_queue, latch)
philosopher2.start()
philosopher3 = diningphilosophers(3, fork3, fork4, operate_queue, latch)
philosopher3.start()
philosopher4 = diningphilosophers(4, fork4, fork5, operate_queue, latch)
philosopher4.start()
latch.wait()
queue_list = 
for i in range(5 * 5 * n):
print(queue_list)

Python實現哲學家就餐問題

哲學家就餐問題

哲學家就餐問題

哲學家就餐問題

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