Python Queue队列

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

queue在使用多进程之间交换安全信息的时候特别有用

class queue.Queue(maxsize=0) #先入先出

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

class queue.PriorityQueue(maxsize=0) #存储数据时可设置优先级的队列 优先级最小最先取出

exception queue.Empty 正常情况下当队列为空则阻塞，如果设置了get_nowaait则会报该异常

Exception raised when non-blocking get() (or get_nowait()) is called on a Queue object which is empty.

exception queue.Full 当设置了put_nowait，队列满时报异常

Exception raised when non-blocking put() (or put_nowait()) is called on a Queue object which is full.

Queue.qsize() 查看队列大小

Queue.empty() #return True if empty   队列为空返回True

Queue.full() # return True if full 

Queue.put(item, block=True, timeout=None) 上传到队列 正常当Q满了 在put就阻塞 如果timeout为True 则等待多少秒后直接抛异常

Queue.put_nowait(item)# 队列满直接抛异常

Queue.get(block=True, timeout=None) #上传到队列，队列空了阻塞

Queue.get_nowait() 队列没数据直接抛异常

Queue.task_done() # q.task_done() 在完成一项工作之后，q.task_done() 函数向任务已经完成的队列发送一个信号. 

Queue.join() 实际上意味着等到队列为空，再执行别的操作

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import queue
class Foo(object):
    def __init__(self,n):
        self.n = n

#q =  queue.Queue(maxsize=30)
#q =  queue.LifoQueue(maxsize=30)
q =  queue.PriorityQueue(maxsize=30)
q.put((2,[1,2,3]))
#q.put(Foo(1))
q.put((10,1))
q.put((3,1))
q.put((5,30))
q.task_done()
q.join()
print(q.get())
print(q.get())
print(q.get())
print(q.get())

生产者消费者模型

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import threading,queue
import time

def consumer(n):
    while True:
        print("\033[32;1mconsumer [%s]\033[0m get task:  %s" % (n,q.get()))
        time.sleep(1)
        q.task_done()#每get一次包子，像其他进程告知队列信息
def producer(n):
    count = 1
    while True:
        #time.sleep(1)
        #if q.qsize() <3:
        print("prodcer [%s] produced a new task : %s" %(n,count))
        q.put(count)
        count +=1
        q.join() #queue is emtpy # 等到队列为空在继续往下执行
        print("all taks has been cosumed by consumers...")

q = queue.Queue()
c1 = threading.Thread(target=consumer,args=[1,])
c2 = threading.Thread(target=consumer,args=[2,])
c3 = threading.Thread(target=consumer,args=[3,])
p = threading.Thread(target=producer,args=["XiaoYu",])
p2 = threading.Thread(target=producer,args=["LiuYao",])
c1.start()
c2.start()
c3.start()
p.start()
p2.start()