Python full stack development Day36-io multiplexing

First, review 1, process, thread, the process: the smallest resource allocation unit in the computer, data isolation, you can use multi-core, data is not a security thread: is the smallest CPU scheduling unit in the computer, data sharing, GIL, data Insecure association: is a part of the thread, is by the user To dispatch, data sharing, data security 2, synchronous, asynchronous, blocking, non-blocking

Async: Doing more than one thing at the same time

Synchronization: One thing is done and then the next.

Blocking: Recv\recvfrom\accept\sleep\input

Non-blocking:

Second, IO multiplexing

IO operation:

File handling: File processing, json.dump/load,input,print,logging

Network operation: Recv/send,resvfrom/sendto,accept/connect

# Why RECV to block
# Waiting for data to come into my Python program's memory

1. Blocking IO:

　　　　　　

　　　　　　

2. Non-blocking IO:

　　　　　　

　　　　　　

code example:

　　　　　　

#Import TimeImportSocketsk=socket.socket () Sk.bind ('127.0.0.1', 9000) ) sk.setblocking (False) sk.listen () Conn_lst=[]del_lst= [] whileTrue:Try: Conn,addr= Sk.accept ()#--Non-blocking, no connection to errorconn_lst.append (conn)Print(conn)exceptBlockingioerror: forConinchConn_lst:#conn1,conn2,conn3            Try: con.send (b'Hello')                Try:                    Print(CON.RECV (1024))#non-blocking no message to error                exceptBlockingioerror:Pass   #recv No news of the error            exceptConnectionreseterror:#send error with no connectioncon.close () del_lst.append (Con) forConinchDel_lst:conn_lst.remove (Con) del_lst.clear ()#The non-blocking form implements the concurrency of the socket server#The non-blocking form implements the concurrent socket server, which consumes too much CPU#The high-speed processing of the program takes up CPU resources when there is no data .

non-blocking io-server

Import= socket.socket () sk.connect('127.0.0.1', 9000) while   True:    Print(SK.RECV (1024x768))    Sk.send (b' Bye ' ) Sk.close ()

non-blocking ioclient

3.IO Multiplexing:

　　　　　　

　　　　　　

ImportSelectImportSocketsk=socket.socket () Sk.bind ('127.0.0.1', 9000) ) sk.setblocking (False) sk.listen () Rlst= [SK]#Listening is the read operation of the objectWlst = []#Listening is the write operation of the objectXlst = []#The listener is an exception operation for the object whileTRUE:RL,WL,XL= Select.select (Rlst,wlst,xlst)#[Sk,conn]     forObjinchRl:#[CONN1,CONN2]        ifobj = =sk:conn,addr= Sk.accept ()#each time the connection is established Connrlst.append (conn)Else: Msg= OBJ.RECV (1024)            ifmsg = = B"': Obj.close () rlst.remove (obj)Continue            Print(msg) obj.send (b'Hello')#Socketserver#concurrent operation of TCP protocol selectors + multithreading

Multiplexing Io-select-sever

ImportSocketsk=socket.socket () Sk.connect ('127.0.0.1', 9000)) whileTrue:sk.send (b'Wahaha')    Print(SK.RECV (1024) ) Sk.close ()#the working mechanism of IO multiplexing Select#Select Windows Polling#Poll Linux Polling, poll can listen more objects than select#Epoll Linux is not a polling method, but instead uses the form of a callback function

Multiplexing io-select-client

# The working mechanism of IO multiplexing Select
# Select Windows Polling
# Poll Linux Polling, poll can listen more objects than select
# Epoll Linux is not polled, but instead takes the form of a callback function

Cross-platform or platform-adaptive IO multiplexing:

ImportSelectorsImportSocketsel=selectors. Defaultselector ()defAccept (obj,mask):"""callback function that is invoked when the selectors instance senses that a user is connected to the server. :p Aram obj::p Aram Mask:: return:"""conn,addr=obj.accept () sel.register (conn, selectors. Event_read, READ)#registering the user connection conn to the selector listener listdefRead (conn,mask):"""callback function that is invoked when the selectors instance senses that a user is sending data. :P Aram Conn::p Aram Mask:: return:"""    Try: Data= CONN.RECV (1024)        if  notData#Null throws an exception handled by the exception handling statement below            RaiseException conn.send (Data+'_SB'. Encode ('Utf-8'))    exceptException as E:Print('closing', Conn) sel.unregister (conn) conn.close () SK=Socket.socket () sk.setsockopt (socket). Sol_socket, SOCKET. SO_REUSEADDR,1) Sk.bind ('127.0.0.1', 9000) ) Sk.listen () sk.setblocking (False) sel.register (SK, selectors. Event_read, accept) while1: Events= Sel.select ()#[Sk,conn1,conn2 ...] who has the new data will return who     forKey, MaskinchEvents:callback= Key.data#Back to functionCallback (Key.fileobj, mask)#Execute callback function

Selectors-server

 import   Socketsk  = Socket.socket () Sk.connect (( "   127.0.0.1   ", 9000))  while  1 = input ("  >>>   " ) sk.send (Inp.encode (  " utf-8  "   print  (Sk.recv (1024x768). Decode ("  utf-8   )) 

selectors-client

4. Asynchronous IO:

　　　　　　

5. Various IO comparisons:

　　　　　　

Python full stack development Day36-io multiplexing