(20)一组生产者进程和一组消费者进程共享9个缓冲区,每个缓冲区可以存放一个整数。生产者进程每次一次性地向三个缓冲区中写入整数,消费者进程每次从缓冲区取出一个整数。请用:①信号量和PV操作;②管程,写出能够正确执行的程序。
时间: 2023-06-12 08:06:43 浏览: 48
①信号量和PV操作实现:
```python
# 初始化信号量
empty = [Semaphore(3) for i in range(3)]
full = [Semaphore(0) for i in range(9)]
mutex = Semaphore(1)
# 缓冲区
buffer = [0 for i in range(9)]
in_ = [0, 0, 0]
out_ = [0, 0, 0]
# 生产者进程
def producer(i):
while True:
item = produce_item() # 生产一个整数
empty[i].wait() # 等待空缓冲区
mutex.wait() # 互斥地访问缓冲区
insert_item(item, i) # 将整数写入缓冲区
mutex.signal() # 释放缓冲区的访问权
full[i*3].signal() # 唤醒对应的消费者进程
full[i*3+1].signal()
full[i*3+2].signal()
# 消费者进程
def consumer(i):
while True:
full[i].wait() # 等待满缓冲区
mutex.wait() # 互斥地访问缓冲区
item = remove_item(i) # 从缓冲区取出整数
mutex.signal() # 释放缓冲区的访问权
empty[i//3].signal() # 唤醒对应的生产者进程
# 插入整数到缓冲区
def insert_item(item, i):
buffer[in_[i]] = item
in_[i] = (in_[i] + 1) % 3
# 从缓冲区取出整数
def remove_item(i):
item = buffer[out_[i]]
out_[i] = (out_[i] + 1) % 3
return item
```
②管程实现:
```python
# 定义缓冲区类
class Buffer(object):
def __init__(self):
self.buffer = [0 for i in range(9)]
self.in_ = [0, 0, 0]
self.out_ = [0, 0, 0]
self.empty = [Condition(Lock()) for i in range(3)]
self.full = [Condition(Lock()) for i in range(9)]
# 生产者进程调用的方法
def insert_item(self, item, i):
self.empty[i].acquire() # 等待空缓冲区
self.buffer[self.in_[i]] = item # 将整数写入缓冲区
self.in_[i] = (self.in_[i] + 1) % 3
self.full[i*3].notify() # 唤醒对应的消费者进程
self.full[i*3+1].notify()
self.full[i*3+2].notify()
self.empty[i].release() # 释放空缓冲区
# 消费者进程调用的方法
def remove_item(self, i):
self.full[i].acquire() # 等待满缓冲区
item = self.buffer[self.out_[i]] # 从缓冲区取出整数
self.out_[i] = (self.out_[i] + 1) % 3
self.full[i].notify() # 唤醒对应的生产者进程
self.empty[i//3].notify()
self.full[(i//3)*3+(i+1)%3].notify()
return item
# 定义生产者进程类
class Producer(Thread):
def __init__(self, buffer, i):
super().__init__()
self.buffer = buffer
self.i = i
def run(self):
while True:
item = produce_item() # 生产一个整数
self.buffer.insert_item(item, self.i) # 将整数写入缓冲区
# 定义消费者进程类
class Consumer(Thread):
def __init__(self, buffer, i):
super().__init__()
self.buffer = buffer
self.i = i
def run(self):
while True:
item = self.buffer.remove_item(self.i) # 从缓冲区取出整数
consume_item(item) # 消费一个整数
# 初始化缓冲区
buffer = Buffer()
# 初始化生产者进程和消费者进程
producers = [Producer(buffer, i) for i in range(3)]
consumers = [Consumer(buffer, i) for i in range(9)]
# 启动生产者进程和消费者进程
for producer in producers:
producer.start()
for consumer in consumers:
consumer.start()
```