python 中 list 是否是线程安全的？

是不是不共享数据就不会发生线程不安全？

线程安全就是多线程访问时，采取了加锁的机制，当一个线程访问该类的某个数据时，进行保护，其他线程不能进行访问知道该线程读取完，其他的线程才可使用，不会出现数据不一致或数据污染的问题

线程不安全就是不提供数据访问保护，有可能出现多个线程现后更改数据造成所得到的数据是脏数据。

总的来说，只要线程之间没有共享资源，那么就是线程安全的，有共享资源，为了保证线程安全，需要引进锁的机制。

lis = list(range(10000))
print(lis)
print(len(lis))

from share_var import gloable
import threading


def consume():
    for i in gloable.lis:
        with open('aab.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


if __name__ == '__main__':
    from threading import Thread

    t1 = Thread(target=consume, name='t1')
    t2 = Thread(target=consume, name='t2')
    t3 = Thread(target=consume, name='t3')
    t4 = Thread(target=consume, name='t4')
    t1.start()
    t2.start()
    t3.start()
    t4.start()

    t1.join()
    t2.join()
    t3.join()
    t4.join()

from share_var.gloable import lis
import threading


def consume():
    for i in lis:
        with open('aabc.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


if __name__ == '__main__':
    from threading import Thread

    t1 = Thread(target=consume, name='t1')
    t2 = Thread(target=consume, name='t2')
    t3 = Thread(target=consume, name='t3')
    t4 = Thread(target=consume, name='t4')
    t1.start()
    t2.start()
    t3.start()
    t4.start()

    t1.join()
    t2.join()
    t3.join()
    t4.join()

以上代码的区别就是在引入全局变量的时候在引入包和引入变量的区别

执行的效果呢，

-rw-r--r-- 1 lishulong 197121 355506 Mar 18 23:07 aab.txt
-rw-r--r-- 1 lishulong 197121 355537 Mar 18 23:07 aabc.txt

发现结构不相同；

aab.txt

aabc.txt

环境：

$ python -V
Python 3.6.2rc1

得出对于共享的全局 lis 是不安全的在不同的线程中？？

import threading


def consume():
    k = list(range(10000))
    for i in k:
        with open('a.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


if __name__ == '__main__':
    from threading import Thread

    t1 = Thread(target=consume, name='t1')
    t2 = Thread(target=consume, name='t2')
    t3 = Thread(target=consume, name='t3')
    t4 = Thread(target=consume, name='t4')
    t1.start()
    t2.start()
    t3.start()
    t4.start()

    t1.join()
    t2.join()
    t3.join()
    t4.join()

import threading


def consume4():
    k = list(range(10000))
    for i in k:
        with open('a.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


def consume3():
    k = list(range(10000))
    for i in k:
        with open('a.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


def consume1():
    k = list(range(10000))
    for i in k:
        with open('a.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


def consume():
    k = list(range(10000))
    for i in k:
        with open('a.txt', 'a+') as file:
            file.write('{},{}\n'.format(i, threading.current_thread().name))


if __name__ == '__main__':
    from threading import Thread

    t1 = Thread(target=consume, name='t1')
    t2 = Thread(target=consume1, name='t2')
    t3 = Thread(target=consume3, name='t3')
    t4 = Thread(target=consume4, name='t4')
    t1.start()
    t2.start()
    t3.start()
    t4.start()

    t1.join()
    t2.join()
    t3.join()
    t4.join()

单线程跑 ok。

只要是多线程，即使不共享也会出现问题，是gil的问题吗

dist的话，可不好找，，，，，

这个问题也就这样吧，，，，

python 中 list 是否是线程安全的？

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