Python3 - 多线程 - threading 模块（基于win系统）- local组件

本文转载自：https://blog.csdn.net/qq_33961117/article/details/87645427

目录

一、local 简单介绍

1-1 不使用local组件存在的弊端

二、Local组件的简单使用 - local对象.变量名 = 赋值

2-1 自定义字典实现Local的操作

2-2 基于面对对象实现Local

2-3 基于魔法方法实现Local

2-4 基于魔法方法实现单独存储空间的Local

三、实现Local并使其兼容线程和协程 - 参考Flask源码

---

一、local 简单介绍

python3 - 多线程 - threading 模块（基于win系统）- Thread、Timer 组件

当多个线程修改同一个数据时，将该数据复制多份给每个线程单独使用，即为每个线程开辟一块空间进行数据存储

1-1 不使用local组件存在的弊端

多个线程同时操作同一个全局变量，每次操作都会修改值，存在锁机制。导致每个线程取到的起始数据不相同，导致最后结果输出错误。

# 未使用local




from threading import Thread




import time



 



test= -1




def task(arg):



    global test



    test= arg



    # 模拟IO操作，用于实现对全局变量的混乱操作




    time.sleep(2)



    print(test)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()



 



'''



9



9



9



9



9



9



9



9



9



9



'''

二、Local组件的简单使用 - local对象.变量名 = 赋值

总结：由Local组件的简单使用可以看出Local操作类似于字典的操作。

from threading import Thread




from threading import local




import time




from threading import get_ident # get_ident用于获取线程、进程ID号




 



# 初始化local对象



loc= local()



 



def task(arg):



    # 对象.val = 1/2/3/4/5




    loc.value = arg



    time.sleep(2)



    print(loc.value)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()



 



'''



3



1



0



2



5



4



7



6



9



8



'''

2-1 自定义字典实现Local的操作

from threading import get_ident,Thread




import time



 



storage = {}



 



def set(k,v):



    ident = get_ident()



    if ident in storage:



        storage[ident][k] = v



    else:



        storage[ident] = {k:v}



 



def get(k):



    ident = get_ident()



    return storage[ident][k]



 



def task(arg):



    set('val',arg)



    v = get('val')



    print(v)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()

2-2 基于面对对象实现Local

from threading import get_ident,Thread




import time



 



class Local(object):



    storage = {}



    def set(self, k, v):




        ident = get_ident()



        if ident in Local.storage:



            Local.storage[ident][k] = v



        else:



            Local.storage[ident] = {k: v}



    def get(self, k):




        ident = get_ident()



        return Local.storage[ident][k]



 



obj = Local()



 



def task(arg):



    obj.set('val',arg) 



    v = obj.get('val')



    print(v)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()

2-3 基于魔法方法实现Local

from threading import get_ident,Thread




import time



 



class Local(object):



    storage = {}



    def __setattr__(self, k, v):




        ident = get_ident()



        if ident in Local.storage:



            Local.storage[ident][k] = v



        else:



            Local.storage[ident] = {k: v}



    def __getattr__(self, k):




        ident = get_ident()



        return Local.storage[ident][k]



 



obj = Local()



 



def task(arg):



    obj.val = arg



    print(obj.val)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()

2-4 基于魔法方法实现单独存储空间的Local

from threading import get_ident,Thread




import time



 



class Local(object):



    def __init__(self):




        object.__setattr__(self,'storage',{})



    def __setattr__(self, k, v):




        ident = get_ident()



        if ident in self.storage:



            self.storage[ident][k] = v



        else:



            self.storage[ident] = {k: v}



    def __getattr__(self, k):




        ident = get_ident()



        return self.storage[ident][k]



 



obj = Local()



 



def task(arg):



    obj.val = arg



    obj.xxx = arg



    print(obj.val)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()

三、实现Local并使其兼容线程和协程 - 参考Flask源码

try:



    from greenlet import getcurrent as get_ident




except Exception as e:



    from threading import get_ident




from threading import Thread



 




import time



 



class Local(object):



    def __init__(self):




        object.__setattr__(self,'storage',{})



    def __setattr__(self, k, v):




        ident = get_ident()



        if ident in self.storage:



            self.storage[ident][k] = v



        else:



            self.storage[ident] = {k: v}



    def __getattr__(self, k):




        ident = get_ident()



        return self.storage[ident][k]



 



obj = Local()



 



def task(arg):



    obj.val = arg



    obj.xxx = arg



    print(obj.val)



 




for i in range(10):



    t = Thread(target=task,args=(i,))



    t.start()