并发编程2
目录
代码创建进程
创建进程的方式有哪些
- 鼠标双击桌面一个应用图标
- 代码创建
代码创建的两种方式
# 第一种代码创建进程的方式
from multiprocessing import Process
import time
def task(process_name):
print('the subprocess %s is running' % process_name)
time.sleep(3)
print('the subprocess %s is over' % process_name)
if __name__ == '__main__':
p = Process(target=task, args=('meta',)) # 创建一个进程对象
p.start() # 创建一个新的进程
print('主进程')
# 第二种代码创建进程的方式
from multiprocessing import Process
import time
class MyProcess(Process):
def __init__(self, process_name):
self.process_name = process_name
super().__init__()
def run(self):
print('the subprocess %s is running' % self.process_name)
time.sleep(3)
print('the subprocess %s is over' % self.process_name)
if __name__ == '__main__':
p = MyProcess('mi_chat')
p.start()
print('主进程')
进程循环
# 客户端
import socket
client = socket.socket()
client.connect(('127.0.0.1', 8066))
count = 1
send_msg = input('请输入发送的内容>>>:').strip()
while count < 9:
client.send(send_msg.encode('utf8'))
data = client.recv(1024)
count += 1
print(data.decode('utf8'))
# 服务端
import socket
from multiprocessing import Process
def get_server():
server = socket.socket()
server.bind(('127.0.0.1', 8066))
server.listen(4)
return server
def talk(sock):
count = 1
while count < 9:
count += 1
data = sock.recv(1024)
print(data.decode('utf8'))
sock.send(f'我们已经收到您的消息'.encode('utf8'))
if __name__ == '__main__':
server = get_server()
count = 1
while count < 9:
sock, addr = server.accept()
count += 1
p = Process(target=talk, args=(sock,))
p.start()
join方法
# join方法让主进程代码等待子进程代码运行完毕再执行
from multiprocessing import Process
import time
def task(process_name, time_arg):
print(f'the subprocess: {process_name} is running')
time.sleep(time_arg)
print(f'the subprocess: {process_name} is over')
if __name__ == '__main__':
p1 = Process(target=task, args=('qq', 1))
p2 = Process(target=task, args=('tmall', 2))
p3 = Process(target=task, args=('jd', 3))
p4 = Process(target=task, args=('pxx', 4))
start_time = time.time()
p1.start()
p2.start()
p3.start()
p4.start()
p1.join()
p2.join()
p3.join()
p4.join()
end_time = time.time()
sum_time = end_time - start_time
print('主进程', f'总耗时:{sum_time}') # 主进程 总耗时:4.281822919845581
# start一个join交替执行的情况
from multiprocessing import Process
import time
def task(process_name, time_arg):
print(f'the subprocess: {process_name} is running')
time.sleep(time_arg)
print(f'the subprocess: {process_name} is over')
if __name__ == '__main__':
p1 = Process(target=task, args=('qq', 1))
p2 = Process(target=task, args=('tmall', 2))
p3 = Process(target=task, args=('jd', 3))
p4 = Process(target=task, args=('pxx', 4))
start_time = time.time()
p1.start()
p1.join()
p2.start()
p2.join()
p3.start()
p3.join()
p4.start()
p4.join()
end_time = time.time()
sum_time = end_time - start_time
print('主进程', f'总耗时:{sum_time}') # 主进程 总耗时:10.786401271820068
进程间数据默认隔离
from multiprocessing import Process
nationality = 'China'
def task():
global nationality
nationality = 'USA'
if __name__ == '__main__':
p = Process(target=task)
p.start()
p.join() # 目的是子进程代码运行结束再执行打印操作
print(nationality) # China
进程对象相关属性和方法
查看进程的方法
cmd
windows: tasklist
mac: ps -ef
python代码
current_process函数
# current_process函数
from multiprocessing import Process,current_process
import time
class MyProcess(Process):
def __init__(self, process_name):
self.process_name = process_name
super().__init__()
def run(self):
print('the subprocess %s is running' % self.process_name)
print(current_process().pid)
time.sleep(3)
print('the subprocess %s is over' % self.process_name)
if __name__ == '__main__':
p = MyProcess('mi_chat')
p.start()
print('主进程')
print(current_process().pid)
os模块
# os模块
from multiprocessing import Process,current_process
import time
import os
class MyProcess(Process):
def __init__(self, process_name):
self.process_name = process_name
super().__init__()
def run(self):
print('the subprocess %s is running' % self.process_name)
print(os.getpid())
print(os.getppid())
time.sleep(3)
print('the subprocess %s is over' % self.process_name)
if __name__ == '__main__':
p = MyProcess('mi_chat')
p.start()
print('主进程')
print(os.getpid())
僵尸进程与孤儿进程
僵尸进程
主进程默认需要等待子进程结束才会结束，所有的子进程在运行结束之后都会变成僵尸进程
僵尸进程保留着pid和一些运行过程记录方便主进程查看，这些信息会被主进程回收
孤儿进程
子进程存活着,父进程意外死亡，子进程会被操作系统自动接管
守护进程
from multiprocessing import Process
import time
def task(process_name):
print(f'子进程:{process_name}运行')
time.sleep(2)
print(f'子进程:{process_name}结束运行')
if __name__ == '__main__':
p = Process(target=task, args=('qq_zone',))
p.daemon = True
p.start()
print('process qq is over')
互斥锁
# 代码模拟抢票
import json
from multiprocessing import Process, Lock
import time
import random
# 查票
def search(name):
with open(r'ticket_data.json', 'r', encoding='utf8') as f:
data = json.load(f)
print(f'{name}查询当前余票:%s' % data.get('ticket_num'))
# 买票
def buy(name):
# 查询剩余票数
with open(r'ticket_data.json', 'r', encoding='utf8') as f:
data = json.load(f)
time.sleep(random.randint(1, 2))
# 判断是否还有余票
if data['ticket_num'] > 0:
data['ticket_num'] -= 1
with open(r'ticket_data.json', 'w', encoding='utf8') as f:
json.dump(data, f)
print(f'{name}抢票成功')
else:
print(f'{name}抢票失败,没有余票')
def run(name, mutex):
search(name)
mutex.acquire() # 抢锁
buy(name)
mutex.release() # 放锁
if __name__ == '__main__':
mutex = Lock()
for i in range(1, 10):
p = Process(target=run, args=('用户:%s' % i, mutex))
p.start()
