produceとcomsumeが同じではないので、結果的に、速度が遅い方に引っ張られることになる。
import time
from threading import Thread, Semaphore, Lock
SIZE = 5
BUFFER = ["" for i in range(SIZE)]
producer_idx: int = 0
mutex = Lock()
empty = Semaphore(SIZE)
full = Semaphore(0)
class Producer(Thread):
def __init__(self, name: str, maximum_items: int = 5):
super().__init__()
self.counter = 0
self.name = name
self.maximum_items = maximum_items
def next_index(self, index: int) -> int:
return (index + 1) % SIZE
def run(self) -> None:
global producer_idx
while self.counter < self.maximum_items:
empty.acquire()
mutex.acquire()
self.counter += 1
BUFFER[producer_idx] = f"{self.name}-{self.counter}"
print(f"{self.name} produced: "
f"'{BUFFER[producer_idx]}' into slot {producer_idx}")
producer_idx = self.next_index(producer_idx)
mutex.release()
full.release()
time.sleep(1)
class Consumer(Thread):
def __init__(self, name: str, maximum_items: int = 10):
super().__init__()
self.name = name
self.idx = 0
self.counter = 0
self.maximum_items = maximum_items
def next_index(self) -> int:
return (self.idx + 1) % SIZE
def run(self) -> None:
while self.counter < self.maximum_items:
full.acquire()
mutex.acquire()
item = BUFFER[self.idx]
print(f"{self.name} consumed item: "
f"'{item}' from slot {self.idx}")
self.idx = self.next_index()
self.counter += 1
mutex.release()
empty.release()
time.sleep(2)
if __name__ == "__main__":
threads = [
Producer("SpongeBob"),
Producer("Patrick"),
Consumer("Squidward")
]
for thread in threads:
thread.start()
for thread in threads:
thread.join()
$ python3 producer_comsumer.py
SpongeBob produced: ‘SpongeBob-1’ into slot 0
Patrick produced: ‘Patrick-1’ into slot 1
Squidward consumed item: ‘SpongeBob-1’ from slot 0
SpongeBob produced: ‘SpongeBob-2’ into slot 2
Patrick produced: ‘Patrick-2’ into slot 3
Squidward consumed item: ‘Patrick-1’ from slot 1
Patrick produced: ‘Patrick-3’ into slot 4
SpongeBob produced: ‘SpongeBob-3’ into slot 0
Patrick produced: ‘Patrick-4’ into slot 1
Squidward consumed item: ‘SpongeBob-2’ from slot 2
SpongeBob produced: ‘SpongeBob-4’ into slot 2
Squidward consumed item: ‘Patrick-2’ from slot 3
Patrick produced: ‘Patrick-5’ into slot 3
Squidward consumed item: ‘Patrick-3’ from slot 4
SpongeBob produced: ‘SpongeBob-5’ into slot 4
Squidward consumed item: ‘SpongeBob-3’ from slot 0
