import multiprocessing

q = multiprocessing.Queue(3) # 初始化的Queue對象，最多能put三條消息
q.put("消息1")
q.put("消息2")
print(q.full())
q.put("消息3")
print(q.full())

# 因為消息列隊已滿下面的try都會拋出異常，第一個try會等待2秒后再拋出異常，第二個Try會立刻拋出異常
try:
    q.put("消息4", True, 2)
except:
    print("消息已滿，現有的消息為%d" % (q.qsize()))

try:
    q.put_nowait("消息4")
except:
    print("消息已滿，現有的消息為%d" % (q.qsize()))

# 推薦的方式，先判斷消息列隊是否已滿，再寫入
if not q.full():
    q.put_nowait("消息4")

# 讀取消息時，先判斷消息列隊是否為空，再讀取
if not q.empty():
    for i in range(q.qsize()):
        print(q.get_nowait())

False
True
消息已滿，現有的消息為3
消息已滿，現有的消息為3
消息1
消息2
消息3

import multiprocessing
import time
import random


def write(q):
    """忘隊列中寫入數據"""
    for value in "ABCD":
        print("Put %s to queue" % (value))
        q.put(value)
        time.sleep(random.random())


def read(q):
    """讀取隊列中的數據"""
    while True:
        if not q.empty():
            value = q.get(True)
            print("Get %s from queue" % (value))
            time.sleep(random.random())
        else:
            break


if __name__ == "__main__":

    q = multiprocessing.Queue()

    pw = multiprocessing.Process(target=write, args=(q,))
    pr = multiprocessing.Process(target=read, args=(q,))

    pw.start()
    pw.join()

    pr.start()
    pr.join()
  
    print('')
    print('所有數據都寫入并且讀完')

Put A to queue
Put B to queue
Put C to queue
Put D to queue
Get A from queue
Get B from queue
Get C from queue
Get D from queue

所有數據都寫入并且讀完