Complete examples of producer and consumer issues implemented by Python

This article illustrates the producer and consumer issues of Python implementation. To share for your reference, the details are as follows:

Producer/consumer problem, classic thread synchronization problem: suppose there is a buffer pool (list), producers put things into it, consumers take from it, the rule is: list is empty, producers can put things; When the list is not empty, the consumer can take things; For simplicity, there is a maximum of one product in the buffer pool temporarily. The producer and consumer work together on one resource: the buffer pool, so each operation needs to lock the resource and release the lock at the end of the operation so that the resource can be synchronized. Using the python implementation, it is necessary to inherit the Thread class to obtain the lock object. The code is as follows:

# -*- coding:utf-8 -*-
#! python2
from threading import Thread
from threading import Lock
import time,random
pro_list = []
lock = Lock()
class Producer(Thread):
  def run(self):
    global pro_list
    while True:
      i = random.randint(0, 100)
      lock.acquire()
      if len(pro_list) > 0:
        print "!--product still in list, wait consumer to get it.."
      else:
        pro_list.append(i)
        print ":::Producer put:", pro_list[0]
      lock.release()
      time.sleep(2)
class Consumer(Thread):
  def run(self):
    global pro_list
    while True:
      lock.acquire()
      if len(pro_list) == 0:
        print "!--No product now, wait producer put in..."
      else:
        print ":::Consumer fetch:", pro_list[0]
        pro_list.pop(0)
      lock.release()
      time.sleep(2)
Producer().start()
Producer().start()
Consumer().start()
Producer().start()
Producer().start()
Consumer().start()
Consumer().start()

Multiple producers and consumers are used to jointly operate the buffer pool, and some of the execution results are as follows:

:::Producer put: 78
!--product still in list, wait consumer to get it..
:::Consumer fetch: 78
:::Producer put: 99
!--product still in list, wait consumer to get it..
:::Consumer fetch: 99
!--No product now, wait producer put in...
:::Producer put: 12
:::Consumer fetch: 12
:::Producer put: 91
!--product still in list, wait consumer to get it..
!--product still in list, wait consumer to get it..
:::Consumer fetch: 91
!--No product now, wait producer put in...
:::Producer put: 63
:::Consumer fetch: 63
:::Producer put: 85
!--product still in list, wait consumer to get it..
!--product still in list, wait consumer to get it..
:::Consumer fetch: 85
!--No product now, wait producer put in...
:::Producer put: 1
:::Consumer fetch: 1
:::Producer put: 26
!--product still in list, wait consumer to get it..
!--product still in list, wait consumer to get it..
:::Consumer fetch: 26
!--No product now, wait producer put in...
:::Producer put: 8
:::Consumer fetch: 8
:::Producer put: 19
!--product still in list, wait consumer to get it..
!--product still in list, wait consumer to get it..
:::Consumer fetch: 19
!--No product now, wait producer put in...
:::Producer put: 74
!--product still in list, wait consumer to get it..
:::Consumer fetch: 74
:::Producer put: 50
!--product still in list, wait consumer to get it..
:::Consumer fetch: 50
!--No product now, wait producer put in...
:::Producer put: 97
:::Consumer fetch: 97
:::Producer put: 69
!--product still in list, wait consumer to get it..
!--product still in list, wait consumer to get it..
:::Consumer fetch: 69
!--No product now, wait producer put in...
:::Producer put: 41
!--product still in list, wait consumer to get it..
:::Consumer fetch: 41
:::Producer put: 6
!--product still in list, wait consumer to get it..
:::Consumer fetch: 6
!--No product now, wait producer put in...

For more information about Python, please refer to: Python Data Structure and Algorithm Tutorial, Python Function Skills Summary, Python String Manipulation Skills Summary, Python Introduction and Advanced Classic Tutorial and Python Mathematical Operation Skills Summary.

I hope this article has been helpful for Python programming.