Gevent学习之阻塞与非阻塞

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Gevent学习之阻塞与非阻塞

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

2）接收数据阻塞

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

2）非阻塞面临的问题

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

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 ' )

( ' Handling requests , press to quit ' )

while True :

self.handle_request()

return