python基础-进程池、submit同异步调用、shutdown参数、ProcessPoolExecutor进程池、进程池ftp

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引入进程池

在学习线程池之前，我们先看一个例子

from multiprocessing import  Process
import  time
def task(name):print("name",name)time.sleep(1)if __name__ == "__main__":start = time.time()p1 = Process(target=task,args=("safly1",))p2 = Process(target=task, args=("safly2",))p3 = Process(target=task, args=("safly3",))p1.start()p2.start()p3.start()p1.join()p2.join()p3.join()print("main")end = time.time()print(end- start)

输出如下：

name safly1
name safly2
name safly3
main
1.2071197032928467

以上的方式是一个个创建进程，这样的耗费时间才1秒多，虽然高效，但是有什么弊端呢？
如果并发很大的话，会给服务器带来很大的压力，所以引入了进程池的概念

使用ProcessPoolExecutor进程池

Python3.2开始，标准库为我们提供了concurrent.futures模块，它提供了ThreadPoolExecutor和ProcessPoolExecutor两个类，实现了对threading和multiprocessing的进一步抽象，对编写线程池/进程池提供了直接的支持。

通过ProcessPoolExecutor 来做示例。
我们来看一个最简单的进程池

from concurrent.futures import ProcessPoolExecutor
import  time
def task(name):print("name",name)time.sleep(1)if __name__ == "__main__":start = time.time()ex = ProcessPoolExecutor(2)for i in range(5):ex.submit(task,"safly%d"%i)ex.shutdown(wait=True)print("main")end = time.time()print(end - start)

输出如下：

E:\python\python_sdk\python.exe "E:/python/py_pro/4 进程池.py"
name safly0
name safly1
name safly2
name safly3
name safly4
main
3.212218999862671

简单解释下：
ProcessPoolExecutor（2）创建一个进程池，容量为2，循环submit出5个进程，然后就在线程池队列里面，执行多个进程，ex.shutdown(wait=True)意思是进程都执行完毕，在执行主进程的内容

使用shutdown

ex.shutdown(wait=True)是进程池内部的进程都执行完毕，才会关闭，然后执行后续代码
如果改成false呢？看如下代码

from concurrent.futures import ProcessPoolExecutor
import  time
def task(name):print("name",name)time.sleep(1)if __name__ == "__main__":start = time.time()ex = ProcessPoolExecutor(2)for i in range(5):ex.submit(task,"safly%d"%i)ex.shutdown(wait=False)print("main")end = time.time()print(end - start)

输出如下：

main
0.01500844955444336
name safly0
name safly1
name safly2
name safly3
name safly4

使用submit同步调用

同步调用：提交/调用一个任务，然后就在原地等着，等到该任务执行完毕拿到结果，再执行下一行代码

from concurrent.futures import ProcessPoolExecutor
import time, random, osdef piao(name, n):print('%s is piaoing %s' % (name, os.getpid()))time.sleep(1)return n ** 2if __name__ == '__main__':p = ProcessPoolExecutor(2)start = time.time()for i in range(5):res=p.submit(piao,'safly %s' %i,i).result() #同步调用print(res)p.shutdown(wait=True)print('主', os.getpid())stop = time.time()print(stop - start)

输出如下：

E:\python\python_sdk\python.exe "E:/python/py_pro/4 进程池.py"
safly 0 is piaoing 12996
0
safly 1 is piaoing 14044
1
safly 2 is piaoing 12996
4
safly 3 is piaoing 14044
9
safly 4 is piaoing 12996
16
主 12932
5.202786684036255Process finished with exit code 0

使用submit异步调用

异步调用: 提交/调用一个任务，不在原地等着，直接执行下一行代码

# from multiprocessing import Process,Pool
from concurrent.futures import ProcessPoolExecutor
import time, random, osdef piao(name, n):print('%s is piaoing %s' % (name, os.getpid()))time.sleep(1)return n ** 2if __name__ == '__main__':p = ProcessPoolExecutor(2)objs = []start = time.time()for i in range(5):obj = p.submit(piao, 'safly %s' % i, i)  # 异步调用objs.append(obj)p.shutdown(wait=True)print('主', os.getpid())for obj in objs:print(obj.result())stop = time.time()print(stop - start)

输出如下：

E:\python\python_sdk\python.exe "E:/python/py_pro/4 进程池.py"
safly 0 is piaoing 1548
safly 1 is piaoing 7872safly 2 is piaoing 1548
safly 3 is piaoing 7872safly 4 is piaoing 1548主 7808
0
1
4
9
16
3.202626943588257

输出信息的换行是我标识有输出停顿的
简单说下执行流程：
由于进程池容量是容纳2个进程，所以会2+2+1 三次进入线程池执行，花费3秒

如果我们改下上面的代码，修改的代码如下：

from concurrent.futures import ProcessPoolExecutor
import time, random, osdef piao(name, n):print('%s is piaoing %s' % (name, os.getpid()))time.sleep(1)return n ** 2if __name__ == '__main__':p = ProcessPoolExecutor(2)objs = []start = time.time()for i in range(5):obj = p.submit(piao, 'safly %s' % i, i)  # 异步调用objs.append(obj)for obj in objs:print(obj.result())p.shutdown(wait=True)print('主', os.getpid())stop = time.time()print(stop - start)

输出如下：（同样我用换行，标识出输出的时间段了）

E:\python\python_sdk\python.exe "E:/python/py_pro/4 进程池.py"
safly 0 is piaoing 7852
safly 1 is piaoing 8484safly 2 is piaoing 7852
0
safly 3 is piaoing 8484
1safly 4 is piaoing 7852
4
916
主 6816
3.178352117538452

进程池实现ftp

服务端：

from socket import *
from concurrent.futures import ProcessPoolExecutor
import osserver=socket(AF_INET,SOCK_STREAM)
server.setsockopt(SOL_SOCKET,SO_REUSEADDR,1)
server.bind(('127.0.0.1',8080))
server.listen(5)def talk(conn,client_addr):print('进程pid: %s' %os.getpid())while True:try:msg=conn.recv(1024)if not msg:breakconn.send(msg.upper())except Exception:breakif __name__ == '__main__':p=ProcessPoolExecutor(5)while True:conn,client_addr=server.accept()p.submit(talk,conn,client_addr)

客户端：

from socket import *client=socket(AF_INET,SOCK_STREAM)
client.connect(('127.0.0.1',8080))while True:msg=input('>>: ').strip()if not msg:continueclient.send(msg.encode('utf-8'))msg=client.recv(1024)print(msg.decode('utf-8'))

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