Python Message Queuing queue

Example 1: Message Queuing queue, do not name the file "queue.py", otherwise it will report the exception "Importerror:cannot Import name ' queue '"

#coding =utf-8from multiprocessing Import Queue q = Queue (3) #初始化一个Queue对象, you can receive up to three put messages Q.put (' message-1 ') q.put (' Message-2 ') print (Q.full ()) #False, is full of q.put (' message-3 ') print (Q.full ()) #True # Because the message queue is full, the following try throws an exception, The first try waits 2 seconds before throwing an exception, and the second try throws an exception immediately try:q.put (' message-4 ', true,2) except:print (' EXCEPT1, message queue full, number of existing messages:%s '%q.qsize ()) Try:q.put_nowait (' message-4 ') except:print (' Except2, message queue full, number of existing messages:%s '%q.qsize ()) #判断队列是否已满if not Q.full (): Q.put_ NoWait (' message-4 ') #读取消息时, first determine whether the message queue is empty, read if not Q.empty (): For I in range (Q.qsize ()):p rint (Q.get ()) #q. Get will block, q.get_ NoWait () does not block, but throws an exception

False

True

EXCEPT1, Message queue full, number of existing messages: 3

EXCEPT2, Message queue full, number of existing messages: 3

Message-1

Message-2

Message-3

Example two: interprocess communication through process

From multiprocessing import Process,queueimport os,time,random #写数据def write (q): For value in [' A ', ' B ', ' C ']:p rint (' Put%s To queue ... '%value) q.put (value) time.sleep (Random.random ()) #读数据def read (q): While True:if not Q.empty (): value = Q.get ( True) print (' Get%s from queue ... '%value) time.sleep (Random.random ()) else:breakif __name__ = = ' __main__ ':p rint (' Start ... ') q = Queue () #父进程的queue传递给子进程pw = Process (target=write,args= (q,)) PR = Process (target=read,args= (q,)) #写进程pw. Start ( ) Pw.join () #读进程pr. Start () Pr.join () print (' Done ... ')

Start ...

Put A to queue ...

Put B to queue ...

Put C to queue ...

Get A from Queue ...

Get B from Queue ...

Get C from Queue ...

Done ...

Example three: inter-process communication through manager

From multiprocessing import Manager,poolimport os,time,random #写数据def writer (q):p rint (' writer start (%s), parent process is (%s) '% ( Os.getpid (), Os.getppid ())))) for I in ' Chaoge ': q.put (i) #读数据def reader (q):p rint (' Reader startup (%s), parent process is (%s) '% (Os.getpid (), Os.getppid ()))) for I in Range (Q.qsize ()):p rint (' Reader fetches from queue to message:%s '%q.get ()) If __name__ = = ' __main__ ':p rint (' (%s) Start '%os.getpid ()) q = Manager (). Queue () #使用Manager中的Queue来初始化po =pool () #使用阻塞模式创建进程 so that you do not need to use a dead loop in reader, you can wait for the write execution to finish, then use Readerpo.apply (writer, (q ,)) po.apply (reader, (q,)) #写进程po. Close () Po.join () print (' (%s) End '%os.getpid ())

(7720) Start

Writer Start (7284), parent process is (7720)

Reader Startup (8712), parent process is (7720)

Reader gets the message from the queue: C

Reader gets the message from the queue: H

Reader gets the message from the queue: a

Reader gets the message from the queue: O

Reader gets the message from the queue: g

Reader gets the message from the queue: E

(7720) End

Python Message Queuing queue