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Python多線程同步---文件讀寫控制方法

更新時(shí)間：2019年02月12日 09:05:46 作者：愛橙子的OK繃

今天小編就為大家分享一篇Python多線程同步---文件讀寫控制方法，具有很好的參考價(jià)值，希望對大家有所幫助。一起跟隨小編過來看看吧

1、實(shí)現(xiàn)文件讀寫的文件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以內(nèi)追加進(jìn)去
 else:
  fp = open('schedule_times.txt', 'w')#10以外重新寫入
  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、不加鎖對文件進(jìn)行多線程讀寫。

file_lock.py

#! /usr/bin/env python
#coding=utf-8

from threading import Thread
import threading
import time
from ltz_schedule_times import *

#1、不加鎖
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()

得到結(jié)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!

文件寫入結(jié)果：

Python多線程同步---文件讀寫控制

以上結(jié)果可以看出，不加鎖多線程讀寫文件會(huì)出現(xiàn)錯(cuò)誤。

2.2、加鎖對文件進(jìn)行多線程讀寫。

file_lock.py

#! /usr/bin/env python
#coding=utf-8

from threading import Thread
import threading
import time
from ltz_schedule_times import *

#2、加鎖
mu = threading.Lock() #1、創(chuàng)建一個(gè)鎖
def lock_test():
 #time.sleep(0.1) 
 if mu.acquire(True): #2、獲取鎖狀態(tài)，一個(gè)線程有鎖時(shí)，別的線程只能在外面等著
  schedule_times = ReadTimes()
  print schedule_times
  schedule_times = schedule_times + 1
  WriteTimes(schedule_times)
  mu.release() #3、釋放鎖  

if __name__ == '__main__':

 for i in range(5):
  Thread(target = lock_test, args=()).start()

結(jié)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!

文件寫入結(jié)果：

Python多線程同步---文件讀寫控制