实例
#!/usr/bin/env python #-*- coding:utf-8 -*- import SocketServer class Myserver(SocketServer.BaseRequestHandler): def handle(self): conn = self.request print self.client_address conn.sendall("我能同时处理多个请求！") flag = True while flag: data = conn.recv(1024) if data == "exit": flag = False else: conn.sendall(data) if __name__ == "__main__": server = SocketServer.ThreadingTCPServer(("localhost",8000),Myserver) server.serve_forever()
client请求原理图
源码解析图
源码
class ThreadingTCPServer(ThreadingMixIn, TCPServer): pass
class ThreadingMixIn: """Mix-in class to handle each request in a new thread.""" # Decides how threads will act upon termination of the # main process daemon_threads = False def process_request_thread(self, request, client_address): """Same as in BaseServer but as a thread. In addition, exception handling is done here. """ try: self.finish_request(request, client_address) self.shutdown_request(request) except: self.handle_error(request, client_address) self.shutdown_request(request) def process_request(self, request, client_address): """Start a new thread to process the request.""" t = threading.Thread(target = self.process_request_thread, args = (request, client_address)) t.daemon = self.daemon_threads t.start()
class TCPServer(BaseServer): """Base class for various socket-based server classes. Defaults to synchronous IP stream (i.e., TCP). Methods for the caller: - __init__(server_address, RequestHandlerClass, bind_and_activate=True) - serve_forever(poll_interval=0.5) - shutdown() - handle_request() # if you don't use serve_forever() - fileno() -> int # for select() Methods that may be overridden: - server_bind() - server_activate() - get_request() -> request, client_address - handle_timeout() - verify_request(request, client_address) - process_request(request, client_address) - shutdown_request(request) - close_request(request) - handle_error() Methods for derived classes: - finish_request(request, client_address) Class variables that may be overridden by derived classes or instances: - timeout - address_family - socket_type - request_queue_size (only for stream sockets) - allow_reuse_address Instance variables: - server_address - RequestHandlerClass - socket """ address_family = socket.AF_INET socket_type = socket.SOCK_STREAM request_queue_size = 5 allow_reuse_address = False def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True): """Constructor. May be extended, do not override.""" BaseServer.__init__(self, server_address, RequestHandlerClass) self.socket = socket.socket(self.address_family, self.socket_type) if bind_and_activate: try: self.server_bind() self.server_activate() except: self.server_close() raise def server_bind(self): """Called by constructor to bind the socket. May be overridden. """ if self.allow_reuse_address: self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.socket.bind(self.server_address) self.server_address = self.socket.getsockname() def server_activate(self): """Called by constructor to activate the server. May be overridden. """ self.socket.listen(self.request_queue_size) def server_close(self): """Called to clean-up the server. May be overridden. """ self.socket.close() def fileno(self): """Return socket file number. Interface required by select(). """ return self.socket.fileno() def get_request(self): """Get the request and client address from the socket. May be overridden. """ return self.socket.accept() def shutdown_request(self, request): """Called to shutdown and close an individual request.""" try: #explicitly shutdown. socket.close() merely releases #the socket and waits for GC to perform the actual close. request.shutdown(socket.SHUT_WR) except socket.error: pass #some platforms may raise ENOTCONN here self.close_request(request) def close_request(self, request): """Called to clean up an individual request.""" request.close()
class BaseServer: timeout = None def __init__(self, server_address, RequestHandlerClass): """Constructor. May be extended, do not override.""" self.server_address = server_address self.RequestHandlerClass = RequestHandlerClass self.__is_shut_down = threading.Event() self.__shutdown_request = False ...... def serve_forever(self, poll_interval=0.5): """Handle one request at a time until shutdown. Polls for shutdown every poll_interval seconds. Ignores self.timeout. If you need to do periodic tasks, do them in another thread. """ self.__is_shut_down.clear() try: while not self.__shutdown_request: r, w, e = _eintr_retry(select.select, [self], [], [], poll_interval) if self in r: self._handle_request_noblock() finally: self.__shutdown_request = False self.__is_shut_down.set() ............ def _handle_request_noblock(self): """Handle one request, without blocking. I assume that select.select has returned that the socket is readable before this function was called, so there should be no risk of blocking in get_request(). """ try: request, client_address = self.get_request() except socket.error: return if self.verify_request(request, client_address): try: self.process_request(request, client_address) except: self.handle_error(request, client_address) self.shutdown_request(request) else: self.shutdown_request(request) ........... def finish_request(self, request, client_address): """Finish one request by instantiating RequestHandlerClass.""" self.RequestHandlerClass(request, client_address, self) def shutdown_request(self, request): """Called to shutdown and close an individual request.""" self.close_request(request)
延伸
实现多进程，与多线程同理，不过使用的是ForkingTCPServer()类。
ForkingTCPServer源码：
class ForkingTCPServer(ForkingMixIn, TCPServer): pass
class ForkingMixIn: """Mix-in class to handle each request in a new process.""" timeout = 300 active_children = None max_children = 40 def collect_children(self): """Internal routine to wait for children that have exited.""" if self.active_children is None: return # If we're above the max number of children, wait and reap them until # we go back below threshold. Note that we use waitpid(-1) below to be # able to collect children in size(<defunct children>) syscalls instead # of size(<children>): the downside is that this might reap children # which we didn't spawn, which is why we only resort to this when we're # above max_children. while len(self.active_children) >= self.max_children: try: pid, _ = os.waitpid(-1, 0) self.active_children.discard(pid) except OSError as e: if e.errno == errno.ECHILD: # we don't have any children, we're done self.active_children.clear() elif e.errno != errno.EINTR: break # Now reap all defunct children. for pid in self.active_children.copy(): try: pid, _ = os.waitpid(pid, os.WNOHANG) # if the child hasn't exited yet, pid will be 0 and ignored by # discard() below self.active_children.discard(pid) except OSError as e: if e.errno == errno.ECHILD: # someone else reaped it self.active_children.discard(pid) def handle_timeout(self): """Wait for zombies after self.timeout seconds of inactivity. May be extended, do not override. """ self.collect_children() def process_request(self, request, client_address): """Fork a new subprocess to process the request.""" self.collect_children() pid = os.fork() if pid: # Parent process if self.active_children is None: self.active_children = set() self.active_children.add(pid) self.close_request(request) #close handle in parent process return else: # Child process. # This must never return, hence os._exit()! try: self.finish_request(request, client_address) self.shutdown_request(request) os._exit(0) except: try: self.handle_error(request, client_address) self.shutdown_request(request) finally: os._exit(1)