Pythonでキューを使う

import queue

q = queue.Queue()

print("start insert")
q.put("1")
q.put("2")
q.put("3")
q.put("4")
print("end of insert")

while not q.empty():
    print(q.get())
#;

start insert
end of insert
1
2
3
4

import queue

q = queue.Queue()

print(q.qsize()) # 0
q.put("1")
print(q.qsize()) # 1
q.put("2")
print(q.qsize()) # 2
q.get()
print(q.qsize()) # 1

import queue

q = queue.Queue(2)

q.put("1")
print(q.full()) # False
q.put("2")
print(q.full()) # True

import collections

q = collections.deque([], 2)

q.append("1")
q.append("2")
q.append("3")

while 0 < len(q):
    print(q.popleft())
#;

2
3

import collections

q = collections.deque([], 2)

q.append("1")
q.append("2")
q.append("3")

while 0 < len(q):
    print(q.pop())
#;

3
2

import collections

q = collections.deque([], 2)
print(q.popleft())

Traceback (most recent call last):
  File "index.py", line 4, in <module>
    print(q.popleft())
IndexError: pop from an empty deque