Python多线程同步---文件读写控制方法


						1、实现文件读写的文件ltz_schedule_times.py





#! /usr/bin/env python

#coding=utf-8

import os



def ReadTimes():

 res = []

 if os.path.exists('schedule_times.txt'):

  fp = open('schedule_times.txt', 'r')

 else:

  os.system('touch schedule_times.txt')

  fp = open('schedule_times.txt', 'r')

 try:

  line = fp.read()

  if line == None or len(line)==0:

   fp.close()

   return 0

  tmp = line.split()

  print 'tmp: ', tmp

  schedule_times = int(tmp[-1])

 finally:

  fp.close()

 #print schedule_times

 return schedule_times



def WriteTimes(schedule_times):

 if schedule_times <= 10:

  fp = open('schedule_times.txt', 'a+')#10以内追加进去

 else:

  fp = open('schedule_times.txt', 'w')#10以外重新写入

  schedule_times = 1

 print 'write schedule_times start!'

 try:



  fp.write(str(schedule_times)+'\n')

 finally:

  fp.close()

  print 'write schedule_times finish!'



if __name__ == '__main__':



 schedule_times = ReadTimes()

 #if schedule_times > 10:

 # schedule_times = 0

 print schedule_times

 schedule_times = schedule_times + 1

 WriteTimes(schedule_times)







2.1、不加锁对文件进行多线程读写。

file_lock.py





#! /usr/bin/env python

#coding=utf-8



from threading import Thread

import threading

import time

from ltz_schedule_times import *



#1、不加锁

def lock_test():

 time.sleep(0.1) 

 schedule_times = ReadTimes()

 print schedule_times

 schedule_times = schedule_times + 1

 WriteTimes(schedule_times)





if __name__ == '__main__':



 for i in range(5):

  Thread(target = lock_test, args=()).start()







得到结果：





0

write schedule_times start!

write schedule_times finish!

tmp: tmp: tmp: tmp:  [[[['1''1''1''1']]]]







11



1

 1

write schedule_times start!write schedule_times start!



write schedule_times start!write schedule_times start!



write schedule_times finish!

write schedule_times finish!

write schedule_times finish!write schedule_times finish!







文件写入结果：



以上结果可以看出，不加锁多线程读写文件会出现错误。

2.2、加锁对文件进行多线程读写。

file_lock.py





#! /usr/bin/env python

#coding=utf-8



from threading import Thread

import threading

import time

from ltz_schedule_times import *



#2、加锁

mu = threading.Lock() #1、创建一个锁

def lock_test():

 #time.sleep(0.1) 

 if mu.acquire(True): #2、获取锁状态，一个线程有锁时，别的线程只能在外面等着

  schedule_times = ReadTimes()

  print schedule_times

  schedule_times = schedule_times + 1

  WriteTimes(schedule_times)

  mu.release() #3、释放锁  



if __name__ == '__main__':



 for i in range(5):

  Thread(target = lock_test, args=()).start()







结果：





0

write schedule_times start!

write schedule_times finish!

tmp: ['1']

1

write schedule_times start!

write schedule_times finish!

tmp: ['1', '2']

2

write schedule_times start!

write schedule_times finish!

tmp: ['1', '2', '3']

3

write schedule_times start!

write schedule_times finish!

tmp: ['1', '2', '3', '4']

4

write schedule_times start!

write schedule_times finish!







文件写入结果：



以上这篇Python多线程同步---文件读写控制方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持中文源码网。