python多线程多进程运行场景
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
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#! /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
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#! /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：
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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
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#! /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：
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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：
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原文链接：https://blog.csdn.net/will130/article/details/50599577