多線程讀寫文件加鎖與不加鎖

1、實現文件讀寫的文件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以內追加進去 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! 

文件寫入結果：

以上結果可以看出，不加鎖多線程讀寫文件會出現錯誤。

2.2、加鎖對文件進行多線程讀寫。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、創建一個鎖 def lock_test(): #time.sleep(0.1) if mu.acquire(True): #2、獲取鎖狀態，一個線程有鎖時，別的線程只能在外面等着 schedule_times = ReadTimes() print schedule_times schedule_times = schedule_times + 1 WriteTimes(schedule_times) mu.release() #3、釋放鎖 if __name__ == '__main__': for i in range(5): Thread(target = lock_test, args=()).start() 

結果：

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! 

文件寫入結果：

達到讀寫效果。