Python Queue隊列

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

queue在使用多進程之間交換安全信息的時候特別有用

class queue.Queue(maxsize=0) #先入先出

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

class queue.PriorityQueue(maxsize=0) #存儲數據時可設置優先級的隊列 優先級最小最先取出

exception queue.Empty 正常情況下當隊列為空則阻塞，如果設置了get_nowaait則會報該異常

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

exception queue.Full 當設置了put_nowait，隊列滿時報異常

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

Queue. qsize () 查看隊列大小

Queue. empty () #return True if empty   隊列為空返回True

Queue. full () # return True if full 

Queue. put (item, block=True, timeout=None) 上傳到隊列 正常當Q滿了 在put就阻塞 如果timeout為True 則等待多少秒后直接拋異常

Queue. put_nowait (item)# 隊列滿直接拋異常

Queue. get (block=True, timeout=None) #上傳到隊列，隊列空了阻塞

Queue.get_nowait() 隊列沒數據直接拋異常

Queue. task_done () # q.task_done() 在完成一項工作之后，q.task_done() 函數向任務已經完成的隊列發送一個信號. 

Queue.join() 實際上意味着等到隊列為空，再執行別的操作

#!/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())

生產者消費者模型

#!/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，像其他進程告知隊列信息
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 # 等到隊列為空在繼續往下執行
        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()