Question

程序：

        import threading
        import time
        import random
        global spoons
        spoons = [1, 1, 1, 1, 1]


    class mythread(threading.Thread):
        running = True

        def __init__(self, name, number):
            threading.Thread.__init__(self)
            self.name = name
            self.number = number

        def run(self):
            while self.running:
                time.sleep( random.uniform(5,10))
                print ('{} is hungry.'.format(self.name))
                self.check()

        def eat(self):
            global spoons
            z=self.number
            print("{} is eating\n".format(self.name))
            time.sleep(random.uniform(1, 5))
            print("{} has finished eating\n".format(self.name))
            if(z == 1):
                spoons[z] = spoons[4] = 1
            else:
                spoons[z] = spoons[z - 1] = 1

        def wait(self):
            time.sleep(1)
            self.check()

        def check(self):
            global spoons
            z = self.number
            if(z % 2 != 0):
                if(spoons[z - 1] == 1):
                    spoons[z - 1] = 0
                    if(z == 1):
                        if(spoons[4] == 1):
                            spoons[4] = 0
                            self.eat()
                        else:
                            self.wait()
                    else:
                        if(spoons[z - 2] == 1):
                            spoons[z - 2] = 0
                            self.eat()
                        else:
                            self.wait()
                else:
                    self.wait()
            else:
                if(spoons[z - 2] == 1):
                    spoons[z - 2] = 0
                    if(spoons[z - 1] == 1):
                        spoons[z - 1] = 0
                        self.eat()
                    else:
                        self.wait()
                else:
                    self.wait()


    Name=['p1', 'p2', 'p3', 'p4', 'p5']
    philosophers= [mythread(name = Name[i % 5], number = (i + 1) % 5)
                for i in range(5)]


    for p in philosophers:
        p.start()


    time.sleep(100)
    mythread.running = False
    print("Now we're finishing.")

输出：

Exception in thread p3:
Traceback (most recent call last):
  File "C:\Users\devda\AppData\Local\Programs\Python\Python36\lib\threading.py", line 916, in _bootstrap_inner
    self.run()
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 22, in run
    def eat(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 56, in check
    self.wait()
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check
    if(spoons[z - 2] == 1):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check
    if(spoons[z - 2] == 1):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check
    if(spoons[z - 2] == 1):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check
    if(spoons[z - 2] == 1):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check
    if(spoons[z - 2] == 1):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check
    if(spoons[z - 2] == 1):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 37, in wait
    def check(self):
  File "D:/ANIKET/osproject/dining_philosophers_probelm.py", line 58, in check

它正在工作一段时间然后显示错误。我认为这是合乎逻辑的错误。但我似乎无法理解是什么我使用的逻辑是偶数编号的哲学家将首先采用右叉，奇数编号的哲学家将首先使用左叉。这个逻辑用在我的代码中的check（）函数中另外因为我使用了很多递归调用，所以这个错误是由于递归堆栈的耗尽而发生的？

Answer 1

代码：

import threading
import random
import time

class Philosopher(threading.Thread):
    running = True
    def __init__(self, xname, forkOnLeft, forkOnRight):
        threading.Thread.__init__(self)
        self.name = xname
        self.forkOnLeft = forkOnLeft
        self.forkOnRight = forkOnRight

    def run(self):
        while(self.running):

            time.sleep( random.uniform(3,13))
            print ('%s is hungry.' % self.name)
            self.dine()

    def dine(self):
        fork1, fork2 = self.forkOnLeft, self.forkOnRight
        while self.running:
            fork1.acquire(True)
            locked = fork2.acquire(False)
            if locked: break
            fork1.release()
            print ('%s swaps forks' % self.name)
            fork1, fork2 = fork2, fork1
        else:
            return

        self.dining()
        fork2.release()
        fork1.release()

    def dining(self):           
        print ('%s starts eating '% self.name)
        time.sleep(random.uniform(1,10))
        print ('%s finishes eating and leaves to think.' % self.name)

def DiningPhilosophers():
    forks = [threading.Lock() for n in range(5)]
    philosopherNames = ('1','2','3','4', '5')

    philosophers= [Philosopher(philosopherNames[i], forks[i%5], forks[(i+1)%5])
            for i in range(5)]


    Philosopher.running = True
    for p in philosophers:
        p.start()
    time.sleep(30)
    Philosopher.running = False

DiningPhilosophers()

尝试此检查是否有效：）

餐饮哲学家代码操作系统

1 个答案: