Python多线程

# 使用 -thread 创建多线程

import _thread
from time import sleep
from datetime import datetime

def aa(name, tt):
    for i in range(3):
        sleep(tt)
        dd = datetime.now().strftime(‘%Y-%m-%d %H-%M-%S‘)
        print(f‘{name}, {dd}\n‘)


_thread.start_new_thread(aa, (‘t1‘, 2))
_thread.start_new_thread(aa, (‘t2‘, 4))




‘‘‘结果
t1, 2020-06-02 17-07-35

t2, 2020-06-02 17-07-37
t1, 2020-06-02 17-07-37


t1, 2020-06-02 17-07-39

t2, 2020-06-02 17-07-41

t2, 2020-06-02 17-07-45
‘‘‘

# 使用 threading 创建多线程

import threading
from time import sleep
from datetime import datetime

def aa(name, tt):
    for i in range(3):
        sleep(tt)
        dd = datetime.now().strftime(‘%Y-%m-%d %H-%M-%S‘)
        print(f‘{name}, {dd}\n‘)



t1 = threading.Thread(target=aa, args=(‘a1‘, 2))
t2 = threading.Thread(target=aa, args=(‘a2‘, 4))

t1.start()
t2.start()

t1.join()
t2.join()


‘‘‘结果

a1, 2020-06-02 17-17-50

a2, 2020-06-02 17-17-52
a1, 2020-06-02 17-17-52


a1, 2020-06-02 17-17-54

a2, 2020-06-02 17-17-56

a2, 2020-06-02 17-18-00

‘‘‘

lock = threading.Lock()  # 创建锁
lock.acquire()           # 锁定
lock.release()           # 解锁

# 在没有使用锁的时候

import threading

num = 100


def cq(n:int):
    global num
    num += n
    num -= n


def run1(n:int):
    for i in range(100000):
        cq(n)


t1 = threading.Thread(target=run1, args=(2,))
t2 = threading.Thread(target=run1, args=(4,))


t1.start()
t2.start()

t1.join()
t2.join()


print(num)



‘‘‘结果
102
‘‘‘

# 使用锁后

import threading

num = 100
lock = threading.Lock()


def cq(n:int):
    global num
    num += n
    num -= n


def run(n:int):
    for i in range(100000):
        # 上锁
        lock.acquire()
        try:
            cq(n)
        finally:
            # 释放锁
            lock.release()


t1 = threading.Thread(target=run, args=(2,))
t2 = threading.Thread(target=run, args=(4,))


t1.start()
t2.start()

t1.join()
t2.join()


print(num)



‘‘‘结果
100
‘‘‘