python之线程

什么是线程？

开启线程的两种方式

方式一:

import time
import random
from threading import Thread


def eat(name):
    print('{} is eating'.format(name))
    time.sleep(random.randrange(1, 5))
    print('{} has gone'.format(name))


if __name__ == "__main__":
    t1 = Thread(target=eat, args=('james', ))
    t1.start()
    print('
主线程')

方式二:

import time
import random
from threading import Thread


class MyThread(Thread):
    def __init__(self, name):
        super().__init__()
        self.name = name

    def run(self):
        print('{} is eating'.format(self.name))
        time.sleep(random.randrange(1, 5))
        print('{} has gone'.format(self.name))


if __name__ == "__main__":
    t1 = MyThread('james')
    t1.start()
    print('
主线程')

进程与线程之间的区别

• 开进程的开销远大于开线程
• 同一进程内的多个线程共享进程的地址空间
• 同一个进程下的线程的pid是一样的

线程的常见属性和方法

获取线程名称

import time
import random
from threading import Thread, current_thread
from multiprocessing import Process, current_process


class MyThread(Thread):
    def __init__(self, name):
        super().__init__()
        self.name = name

    def run(self):
        print('{} is eating'.format(self.name))
        time.sleep(random.randrange(1, 5))
        print(current_thread().getName())
        print('{} has gone'.format(self.name))


if __name__ == "__main__":
    t1 = MyThread('james')
    t1.start()
    print('
主线程', current_thread().getName())

 互斥锁

from threading import Thread, Lock
import time

n = 100

def task():
    global n
    mutex.acquire()
    temp = n
    time.sleep(0.1)
    n = temp - 1
    mutex.release()


if __name__ == "__main__":
    mutex = Lock()
    t_l = []
    for i in range(100):
        t = Thread(target=task)
        t_l.append(t)
        t.start()

    for t in t_l:
        t.join()

    print('主', n)

将并发的过程变为串行的过程