7.3.9

一 线程queue

queue is especially useful in threaded programming when information must be exchanged safely between multiple threads.

有三种不同的用法

1. class queue.Queue(maxsize=0) #队列：先进先出

import queue  # 队列

q = queue.Queue(3)
q.put("first")
q.put(2)
q.put("three")
print(q.get())
print(q.get())
print(q.get())

first
2
three

2. class queue.LifoQueue(maxsize=0) #堆栈：last in fisrt out

import queue
q=queue.LifoQueue()
q.put(1)
q.put(2)
q.put(3)

print(q.get())
print(q.get())
print(q.get())

3
2
1

3. class queue.PriorityQueue(maxsize=0) #优先级队列：存储数据时可设置优先级的队列

结果(数字越小优先级越高,优先级高的优先出队):#put进入一个元组,元组的第一个元素是优先级(通常是数字,也可以是非数字之间的比较),数字越小优先级越高

import queue
q = queue.PriorityQueue(3)  # 优先级，越小优先级越大
q.put([10,'one']) # first 优先级  second data
q.put([30,'two']) # first 优先级  second data
q.put([20,'three']) # first 优先级  second data
print(q.get())
print(q.get())
print(q.get())

[10, 'one']
[20, 'three']
[30, 'two']

Put方式是元组或者列表

import queue
q = queue.PriorityQueue(3)  # 优先级，越小优先级越大
q.put((10,'one')) # first 优先级  second data
q.put((30,'two')) # first 优先级  second data
q.put((20,'three')) # first 优先级  second data
print(q.get())
print(q.get())
print(q.get())

(10, 'one')
(20, 'three')
(30, 'two')

其他参数，阻塞，和超时时间

import queue
q=queue.Queue(3)
q.put(1)
q.put(2)
q.put(3) 
q.put(4,timeout=3)  # 阻塞，3秒后异常退出报，队列满了

import queue
q=queue.Queue(3)
q.put(1)
q.put(2)
q.put(3)
q.put(4,block=True,timeout=3)

q.get也一样。

查看队列是否满了后者空了

import queue
q=queue.Queue(3)
q.put(1)
q.put(2)
q.put(3)
print(q.full())  # 查看队列是否满了
print(q.empty()) # 查看队列是否空了
print(q.get())
print(q.get())
print(q.get())
print(q.full())
print(q.empty())

True
False
1
2
3
False
True