python多线程同步之文件读写控制

2019-11-25 11:49:35

字体：大中小

来源：转载

供稿：网友

本文实例为大家分享了python多线程同步之文件读写控制的具体代码，供大家参考，具体内容如下

1、实现文件读写的文件ltz_schedule_times.py

#! /usr/bin/env python#coding=utf-8import osdef 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_timesdef 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-8from threading import Threadimport threadingimport timefrom 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：

0write schedule_times start!write schedule_times finish!tmp: tmp: tmp: tmp:   [[[['1''1''1''1']]]]111 1write 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-8from threading import Threadimport threadingimport timefrom 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：

0write schedule_times start!write schedule_times finish!tmp: ['1']1write schedule_times start!write schedule_times finish!tmp: ['1', '2']2write schedule_times start!write schedule_times finish!tmp: ['1', '2', '3']3write schedule_times start!write schedule_times finish!tmp: ['1', '2', '3', '4']4write schedule_times start!write schedule_times finish!

文件写入结果：