Python BaseHttpserver, 어떻게 끈을 잡아서 "파괴 된 파이프"오류를 잡는가?

Question

나는 파이썬에서 짧은 URL 번역기 엔진을 짓고, "파쇄 된 파이프"오류 톤을 꼭 보았을 때, BaseHtTPServer 클래스를 사용할 때 가장 잘 함정하는 방법을 궁금합니다.이것은 전체 코드가 아니지만 지금까지하는 일에 대한 아이디어를 제공합니다 :

    from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
    import memcache

    class clientThread(BaseHTTPRequestHandler):

            def do_GET(self):
                    content = None
                    http_code,response_txt,long_url = \
                            self.ag_trans_url(self.path,content,'GET')
                    self.http_output( http_code, response_txt, long_url )
                    return

            def http_output(self,http_code,response_txt,long_url):
                    self.send_response(http_code)
                    self.send_header('Content-type','text/plain')
                    if long_url:
                            self.send_header('Location', long_url)
                    self.end_headers()
                    if response_txt:
                            self.wfile.write(response_txt)
                    return

        def ag_trans_url(self, orig_short_url, post_action, getpost):
                short_url = 'http://foo.co' + orig_short_url

                # fetch it from memcache
                long_url = mc.get(short_url)

                # other magic happens to look it up from db if there was nothing
                # in memcache, etc
                return (302, None, log_url)

def populate_memcache()
        # connect to db, do lots of mc.set() calls

def main():
        populate_memcache()
        try:
                port = 8001
                if len(sys.argv) > 1:
                        port = int(sys.argv[1])
                server = HTTPServer(('',port), clientThread)
                #server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                print '[',str(datetime.datetime.now()),'] short url processing has begun'

                server.serve_forever()
        except KeyboardInterrupt,SystemExit:
                print '^C received, shutting down server'
                server.socket.close()

.

코드 자체는 훌륭하게 작동하지만 생산시에 거의 즉시 오류를 던지기 시작했습니다 :

Traceback (most recent call last):
  File "/usr/lib/python2.5/SocketServer.py", line 222, in handle_request
    self.process_request(request, client_address)
  File "/usr/lib/python2.5/SocketServer.py", line 241, in process_request
    self.finish_request(request, client_address)
  File "/usr/lib/python2.5/SocketServer.py", line 254, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python2.5/SocketServer.py", line 522, in __init__
    self.handle()
  File "/usr/lib/python2.5/BaseHTTPServer.py", line 316, in handle
    self.handle_one_request()
  File "/usr/lib/python2.5/BaseHTTPServer.py", line 310, in handle_one_request
    method()
  File "/opt/short_url_redirector/shorturl.py", line 38, in do_GET
    self.http_output( http_code, response_txt, long_url )
  File "/opt/short_url_redirector/shorturl.py", line 52, in http_output
    self.send_response(http_code)
  File "/usr/lib/python2.5/BaseHTTPServer.py", line 370, in send_response
    self.send_header('Server', self.version_string())
  File "/usr/lib/python2.5/BaseHTTPServer.py", line 376, in send_header
    self.wfile.write("%s: %s\r\n" % (keyword, value))
  File "/usr/lib/python2.5/socket.py", line 274, in write
    self.flush()
  File "/usr/lib/python2.5/socket.py", line 261, in flush
    self._sock.sendall(buffer)
error: (32, 'Broken pipe')

.

이러한 오류의 대부분은 Send_Header () 메서드를 호출하는 데 문제가있는 것으로 보이는 것처럼 보입니다.

self.send_header('Location', long_url)

.

이 IO 예외를 위해 내 코드에서 트랩을 시도하는 데 궁금합니다. 셀프의 각 셀프 호출을 제외하고 / self.end_headers / self.wfile.write 호출을 써서 시도 / 제외하고?다른 오류는 시간에서 시간까지 이런 것입니다. 그러나 어떤 예외를 볼 수있는 예외는 확실하지 않습니다.

Traceback (most recent call last):
  File "/usr/lib/python2.5/SocketServer.py", line 222, in handle_request
    self.process_request(request, client_address)
  File "/usr/lib/python2.5/SocketServer.py", line 241, in process_request
    self.finish_request(request, client_address)
  File "/usr/lib/python2.5/SocketServer.py", line 254, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python2.5/SocketServer.py", line 522, in __init__
    self.handle()
  File "/usr/lib/python2.5/BaseHTTPServer.py", line 316, in handle
    self.handle_one_request()
  File "/usr/lib/python2.5/BaseHTTPServer.py", line 299, in handle_one_request
    self.raw_requestline = self.rfile.readline()
  File "/usr/lib/python2.5/socket.py", line 381, in readline
    data = self._sock.recv(self._rbufsize)
error: (104, 'Connection reset by peer')

.

Answer 1

The "broken pipe" exception means that your code tried to write to a socket/pipe which the other end has closed. If the other end is a web browser, the user could have stopped the request. You can ignore the traceback; it does not indicate a serious problem. If you want to suppress the message, you can put a try ... except block around all of the code in your http_output function, and log the exception if you like.

Additionally, if you want your HTTP server to process more than one request at a time, you need your server class to use one of the SocketServer.ForkingMixIn and SocketServer.ThreadingMixIn classes. Check the documentation of the SocketServer module for details.

Add: The "connection reset by peer" exception means that your code tried to read from a dead socket. If you want to suppress the traceback, you will need to extend the BaseHTTPServer class and override the handle_one_request method to add a try ... except block. You will need a new server class anyway, to implement the earlier suggestion about processing more than one request at a time.

Answer 2

This appears to be a bug in SocketServer, see this link Python Bug: 14574

A fix (works for me in Python 2.7) is to override the SocketServer.StreamRequestHandler finish() method, something like this:

...
def finish(self,*args,**kw):
  try:
    if not self.wfile.closed:
      self.wfile.flush()
      self.wfile.close()
  except socket.error:
    pass
  self.rfile.close()

  #Don't call the base class finish() method as it does the above
  #return SocketServer.StreamRequestHandler.finish(self)

Answer 3

In my application, the error didn't occur in finish(), it occurred in handle(). This fix catches the broken pipe errors:

class MyHTTPRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):

    ...

    def handle(self):
        try:
            BaseHTTPServer.BaseHTTPRequestHandler.handle(self)
        except socket.error:
            pass