0. threading.local 知识点

threading.local

import time
import threading

class Foo(object):
    def __init__(self):
        self.num = 0

val2 = Foo()

def task(i):
    val2.num = i
    time.sleep(1)
    print(val2.num)

for i in range(4):
    t = threading.Thread(target=task,args=(i,))
    t.start()

# 3
# 3
# 3
# 3

import time
import threading

# 当每个线程在执行 val1.xx=1 ，在内部会为此线程开辟一个空间，来存储 xx=1
# val1.xx,找到此线程自己的内存地址去取自己存储 xx
# 其实就是通过线程ID进行标记
val1 = threading.local()

def task(i):
    val1.num = i
    time.sleep(1)
    print(val1.num)

for i in range(4):
    t = threading.Thread(target=task,args=(i,))
    t.start()

# 0
# 2
# 1
# 3