gevent基础之阻塞与非阻塞详解

　　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 ' ) 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/