Python实现哲学家就餐问题实例代码

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):
    queue_list.append(operate_queue.get())
  print(queue_list)