1、Queue

• Init signature: queue.Queue(maxsize=0)
• Docstring: Create a queue object with a given maximum size.If maxsize is <= 0, the queue size is infinite.

from queue import Queue
import randomq = Queue()
print(q, type(q))# <queue.Queue object at 0x000001B6ED33DCA0> <class 'queue.Queue'>

q.put(random.randint(1, 100))
q.put(random.randint(1, 100))
print(q)        # <queue.Queue object at 0x00000184B2FA94C0>
print(q.get())  # 22
print(q.get())  # 83
# print(q.get())  
# it blocks if no item available# print(q.get(timeout=3))  
# it blocks at most 'timeout' seconds and raises the Empty exception if no item was available within that time# print(q.get_nowait())
# Remove and return an item from the queue without blocking.
# Only get an item if one is immediately available. Otherwise raise the Empty exception.

q.maxsize = 3
q.put(random.randint(1, 100))
q.put(random.randint(1, 100))
q.put(random.randint(1, 100))
# q.put(random.randint(1, 100), timeout=3)  # Full
# If 'timeout' is a non-negative number, it blocks at most 'timeout' seconds 
# and raises the Full exception if no free slot was available within that time.

2、Queue & Threading – 1

import threading
import queue
import random
import timeq = queue.Queue()
q.put(random.randint(0, 100))
q.put(random.randint(0, 100))def q_put(q):time.sleep(3)q.put("I'm in function.")time.sleep(0.00001)print("=== function ===")print(q.get())
print(q.get())t = threading.Thread(target=q_put, args=(q,))
t.start()print("=== After Threading ===")print(q.get(timeout=5))

53
54
=== After Threading ===
I'm in function.
=== function ===

3、Queue & Threading – 2

import threading, queueq = queue.Queue()def worker():while True:item = q.get()print(f'working on {item}')print(f'finished {item}')q.task_done()# turn on the worker thread
threading.Thread(target=worker, daemon=True).start()# send five task requests to the worker
for item in range(5):q.put(item)# block until all tasks are done
q.join()
print('all work completed')

working on 0
finished 0
working on 1
finished 1
working on 2
finished 2
working on 3
finished 3
working on 4
finished 4
all work completed