gevent基础之阻塞与非阻塞详解

àì夳堔傛蜴生んèń 2022-07-15 06:59 172阅读 0赞

gevent中一个很大的改进就是将阻塞IO改为非阻塞IO，比如gevent.socket.patch就是将项目中阻塞socket变为非阻塞，因此深刻理解网络IO部分阻塞／非阻塞十分重要。

**1.阻塞调用是指调用结果返回之前，当前线程会被挂起。函数只有在得到结果之后才会返回**

1）connect阻塞

![Center][]

2）接收数据阻塞

![Center 1][]

**2.非阻塞指在不能立刻得到结果之前，该函数不会阻塞当前线程，而会立刻返回**

1）接收数据非阻塞

![Center 2][]

2）非阻塞面临的问题

![Center 3][]

**源码**

1.代码示例

import logging

import time

import errno

logging.basicConfig( level=logging.DEBUG ,

format='%( name ) s : % ( message ) s ' , )

if \_\_name\_\_ == '\_\_main\_\_':

import socket

ip = ' localhost '

port = 58562

logger = logging.getLogger ( ' client ' )

\# Connect to the server

logger.debug( ' creating socket ' )

s = socket.socket ( socket.AF\_INET, socket.SOCK\_STREAM )

logger.debug( ' connecting to server ' )

s.setblocking(0)

try:

s.connect( ( ip , port ) )

except socket.error , msg :

if msg\[0\] != errno.EINPROGRESS :

logger.debug( ' error ' )

exit(1)

\#time.sleep(1)

\# Send the data

message = ' Hello , world '

\#len\_sent = s.send ( message )

logger.debug( ' sending data: "%s"', message )

while True :

try:

len\_sent = s.send ( message )

break

except socket.error, msg :

if msg\[0\] != errno.EAGAIN:

exit(1)

\# Receive a response

logger.debug( ' waiting for response ' )

while True:

try:

response = s.recv( len\_sent )

break

except socket.error, msg:

if msg\[0\] != errno.EAGAIN:

exit(1)

logger.debug( ' response from server: "%s"', response )

\# Clean up

logger.debug( ' closing socket ' )

s.close()

logger.debug( ' done ' )

执行结果

![Center 4][]

2.代码示例

import logging

import sys

import SocketServer

import time

logging.basicConfig(level=logging.DEBUG ,

format='%( name ) s : % ( message ) s ' ,

)

class EchoRequestHandler ( SocketServer.BaseRequestHandler ) :

def \_\_init\_\_( self , request , client\_address , server ) :

self.logger = logging.getLogger ( ' EchoRequestHandler ' )

self.logger.debug( ' \_\_init\_\_ ' )

SocketServer.BaseRequestHandler.\_\_init\_\_(self, request, client\_address, server)

return

def setup ( self ) :

self.logger.debug( ' setup ' )

return SocketServer.BaseRequestHandler.setup ( self )

def handle ( self ) :

self.logger.debug( ' handle ' )

\# Echo the back to the client

data = self.request.recv ( 1024 )

self.logger.debug( ' recv()->"%s"', data )

self.request.send( data )

return

def finish ( self ) :

self.logger.debug( ' finish ' )

return SocketServer.BaseRequestHandler.finish(self)

class EchoServer(SocketServer.TCPServer):

def \_\_init\_\_(self, server\_address, handler\_class=EchoRequestHandler):

self.logger = logging.getLogger (' EchoServer ' )

Self.logger.debug ('\_\_init\_\_')

SocketServer.TCPServer.\_\_init\_\_(self, server\_address, handler\_class)

return

def server\_activate ( self ) :

Self.logger.debug ( ' server\_activate ' )

SocketServer.TCPServer.server\_activate ( self )

return

def serve\_forever ( self ) :

self.logger.debug( ' waiting for reques t ' )

Self.logger.info ( ' Handling requests , press <Ctrl-C> to quit ' )

while True :

self.handle\_request()

return

def handle\_request ( self ) :

Self.logger.debug ( ' handle\_request ' )

return SocketServer.TCPServer.handle\_request ( self )

def verify\_request ( self , request , client\_address ) :

Self.logger.debug ( ' verify\_request ( %s , %s )', request, client\_address)

return SocketServer.TCPServer.verify\_request(self, request, client\_address )

def process\_request (self , request , client\_address ) :

Self.logger.debug ( ' process\_request ( %s , %s ) ' , request , client\_address )

return SocketServer.TCPServer.process\_request (self , request , client\_address )

def server\_close ( self ) :

Self.logger.debug ( ' server\_close ' )

return SocketServer.TCPServer.server\_close ( self )

def finish\_request ( self , request , client\_address ) :

self.logger.debug('finish\_request ( %s , %s ) ' , request , client\_address )

return SocketServer.TCPServer.finish\_request(self , request , client\_address )

def close\_request ( self , request\_address ) :

self.logger.debug ( ' close\_request ( %s ) ' , request\_address )

return SocketServer.TCPServer.close\_request ( self , request\_address )

if \_\_name\_\_ == '\_\_main\_\_' :

import socket

import threading

address = ( ' localhost ' , 0 ) \# let the kernel give us a port

server = EchoServer ( address , EchoRequestHandler )

ip, port = server.server\_address \# find out what port we were given

logger = logging.getLogger ( ' client ' )

logger.info( ' Server on %s : %s ' , ip , port )

server.serve\_forever ()

原文链接：[http://www.maiziedu.com/wiki/frame/block/][http_www.maiziedu.com_wiki_frame_block]

[Center]: /images/20220715/c256ef045f494683afda5e3aa1e1503b.png
[Center 1]: /images/20220715/5a38ff3d3d5548a1a412d74aae8da173.png
[Center 2]: /images/20220715/9df6765926944b77a6b856e98057a8b9.png
[Center 3]: /images/20220715/a7d31052082b410f9145cbd02e9c0c4c.png
[Center 4]: /images/20220715/441c9bcfc5254521ae0d81aea501d53a.png
[http_www.maiziedu.com_wiki_frame_block]: http://www.maiziedu.com/wiki/frame/block/