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
ThreadingTCPServer
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()
ThreadingMixIn
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()
TCPServer
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)
BaseServer部分
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)
ForkingMixIn
时间： 2025-01-01 05:57:37