多线程读写文件加锁与不加锁

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：

达到读写效果。