服務器端：

from socket import *
from threading import Thread

def communicate(conn):
    while True:
        try:
            data=conn.recv(1024)
            if not data:break
            conn.send(data.upper())
        except ConnectionResetError:
            break

    conn.close()

def server(ip,port):
    server 
 
= socket(AF_INET, SOCK_STREAM)
    server.bind((ip,port))
    server.listen(5)

    while True:
        conn, addr = server.accept()
        t=Thread(target=communicate,args=(conn,))
        t.start()

    server.close()

if __name__ == ‘__main__‘:
    server(‘127.0.0.1‘, 8081)

客戶端：

from socket import
 
 *

client=socket(AF_INET,SOCK_STREAM)
client.connect((‘127.0.0.1‘,8081))


while True:
    msg=input(‘>>: ‘).strip()
    if not msg:continue
    client.send(msg.encode(‘utf-8‘))
    data=client.recv(1024)
    print(data.decode(‘utf-8‘))

client.close()

該種實現有什麽弊端嗎？

如果有10萬個客戶端，就得開10萬個線程？單臺服務器支撐得了不？

進程池或線程池實現並發：

from concurrent.futures import ThreadPoolExecutor
from threading import current_thread
import time


def work(n):
    print(n, ‘======‘, current_thread().getName())
    time.sleep(1)


if __name__ == ‘__main__‘:
    pool = ThreadPoolExecutor(3, thread_name_prefix=‘pool_‘)   # 3 是線程池大小

    for i in range(10):   # 任務數
        pool.submit(work, i)   # 單個任務提交到線程池中   def submit(self, fn, *args, **kwargs):

   # pool.shutdown(wait=False)   # 默認是wait=False 不等任務執行結果，就執行主線程接下來的代碼

print(‘主線程。。。。。‘)

運行結果：

0 ====== pool__0
1 ====== pool__1
2 ====== pool__2
主線程。。。。。
3 ====== pool__0
4 ====== pool__1
5 ====== pool__2
6 ====== pool__1
7 ====== pool__2
8 ====== pool__0
9 ====== pool__2

如何做到線程的join效果呢？等任務都執行完後，才執行主程序代碼。

from concurrent.futures import ThreadPoolExecutor
from threading import current_thread
import time


def work(n):
    print(n, ‘======‘, current_thread().getName())
    time.sleep(1)


if __name__ == ‘__main__‘:
    pool = ThreadPoolExecutor(3, thread_name_prefix=‘pool_‘)

    for i in range(10):
        pool.submit(work, i)

    pool.shutdown(wait=True)   # 相當於join的功能。 實際原理是：斷開新任務進到線程池中，等待池中的任務執行完。
    # pool.shutdown(wait=False)   # 默認是wait=False 不等任務執行結果，就執行主線程接下來的代碼 
    print(‘主線程。。。。。‘)

運行結果:

0 ====== pool__0
1 ====== pool__1
2 ====== pool__2
3 ====== pool__1
4 ====== pool__0
5 ====== pool__2
6 ====== pool__1
7 ====== pool__0
8 ====== pool__2
9 ====== pool__1
主線程。。。。。

5.1.22 多線程實現並發