【Python】多进程 多线程

1. 进程 Process

1.1 多进程

# -*- coding: UTF-8 -*-
"""
# 计算8的20次方
"""
import time
import os

from multiprocessing import Process
import os
import time

def long_time_task(i):
    print('子进程: {} - 任务{}'.format(os.getpid(), i))
    time.sleep(2)
    print("结果: {}".format(8 ** 20))

if __name__=='__main__':
    print('当前母进程: {}'.format(os.getpid()))
    start = time.time()
    p1 = Process(target=long_time_task, args=(1,))
    p2 = Process(target=long_time_task, args=(2,))
    print('等待所有子进程完成。')
    p1.start()
    p2.start()
    p1.join()  # 主进程阻塞等待子进程的退出
    p2.join()
    end = time.time()
    print("总共用时{}秒".format((end - start)))

1.2 进程池 Poll

# -*- coding: UTF-8 -*-
"""
# 计算8的20次方
"""
from multiprocessing import Pool, cpu_count
import os
import time

def long_time_task(i):
    print('子进程: {} - 任务{}'.format(os.getpid(), i))
    time.sleep(2)
    print("结果: {}".format(8 ** 20))

if __name__=='__main__':
    print("CPU内核数:{}".format(cpu_count()))
    print('当前母进程: {}'.format(os.getpid()))
    start = time.time()
    p = Pool(8)
    for i in range(9):
        p.apply_async(long_time_task, args=(i,))
    print('等待所有子进程完成。')
    p.close()
    p.join()
    end = time.time()
    print("总共用时{}秒".format((end - start)))

2 线程 Thread

2.1 多线程

# -*- coding: UTF-8 -*-
"""
# 计算8的20次方
"""
import threading
import time


def long_time_task(i):
    print('当前子线程: {} 任务{}'.format(threading.current_thread().name, i))
    time.sleep(2)
    print("结果: {}".format(8 ** 20))


if __name__=='__main__':
    start = time.time()
    print('这是主线程：{}'.format(threading.current_thread().name))
    thread_list = []
    for i in range(1, 3):
        t = threading.Thread(target=long_time_task, args=(i, ))
        thread_list.append(t)

    for t in thread_list:
        t.start()

    for t in thread_list:
        t.join()

    end = time.time()
    print("总共用时{}秒".format((end - start)))

2.2 继承Thread类重写run方法创建新进程

#-*- encoding:utf-8 -*-
import threading
import time


def long_time_task(i):
    time.sleep(2)
    return 8**20

class MyThread(threading.Thread):
    def __init__(self, func, args , name='', ):
        threading.Thread.__init__(self)
        self.func = func
        self.args = args
        self.name = name
        self.result = None

    def run(self):
        print('开始子进程{}'.format(self.name))
        self.result = self.func(self.args[0],)
        print("结果: {}".format(self.result))
        print('结束子进程{}'.format(self.name))

if __name__=='__main__':
    start = time.time()
    threads = []
    for i in range(1, 3):
        t = MyThread(long_time_task, (i,), str(i))
        threads.append(t)

    for t in threads:
        t.start()
    for t in threads:
        t.join()

    end = time.time()
    print("总共用时{}秒".format((end - start)))

2.3 不同线程之间的数据共享, 对共享变量的锁定

# -*- coding: UTF-8 -*-

import threading

class Account:
    def __init__(self):
        self.balance = 0

    def add(self, lock):
        # 获得锁
        lock.acquire()
        for i in range(0, 100000):
            self.balance += 1
        # 释放锁
        lock.release()

    def delete(self, lock):
        # 获得锁
        lock.acquire()
        for i in range(0, 100000):
            self.balance -= 1
            # 释放锁
        lock.release()


if __name__ == "__main__":
    account = Account()
    lock = threading.Lock()
    # 创建线程
    thread_add = threading.Thread(target=account.add, args=(lock,), name='Add')
    thread_delete = threading.Thread(target=account.delete, args=(lock,), name='Delete')

    # 启动线程
    thread_add.start()
    thread_delete.start()

    # 等待线程结束
    thread_add.join()
    thread_delete.join()

    print('The final balance is: {}'.format(account.balance))

The final balance is: 0