Python之queue模块的使用

queue模块的作用

    queue模块提供了一个适用于多线程编程的先进先出（FIFO）数据结构，可以用来在生产者和    消费者线程之间的安全地传递消息或其他数据。它会为调用者处理锁定
，使多个线程可以安全而容易地处理同一个Queue实例。Queue的大小（其中包含的元素个数）有受限，以限制内存使用的或处理。

1、队列的先进先出取写和读的示例

import queue

q = queue.Queue()

for i in range(5):
    q.put(i)

while not q.empty():
    print(q.get(), end=' ')
print()

运行效果

0 1 2 3 4 

2、队列的先进后出取写和读的示例

import queue

q = queue.LifoQueue()

for i in range(5):
    q.put(i)

while not q.empty():
    print(q.get(), end=' ')
print()

运行效果

4 3 2 1 0 

3、设置优先级队列

import functools
import queue
import threading


@functools.total_ordering
class Job:

    def __init__(self, priority, description):
        self.priority = priority
        self.description = description
        print('New job:', description)
        return

    def __eq__(self, other):
        try:
            return self.priority == other.priority
        except AttributeError:
            return NotImplemented

    def __lt__(self, other):
        try:
            return self.priority < other.priority
        except AttributeError:
            return NotImplemented


q = queue.PriorityQueue()

q.put(Job(3, 'Mid-level job'))
q.put(Job(10, 'Low-level job'))
q.put(Job(1, 'Important job'))


def process_job(q):
    while True:
        next_job = q.get()
        print('Processing job:', next_job.description)
        q.task_done()


workers = [
    threading.Thread(target=process_job, args=(q,)),
    threading.Thread(target=process_job, args=(q,)),
]
for w in workers:
    w.setDaemon(True)
    w.start()

q.join()

运行效果

New job: Mid-level job
New job: Low-level job
New job: Important job
Processing job: Important job
Processing job: Mid-level jobProcessing job: Low-level job