I build a short url translator engine in Python, and I'm seeing a TON of "broken pipe" errors, and I'm curious how to trap it best when using the BaseHTTPServer classes. This isn't the entire code, but gives you an idea of what I'm doing so far:
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()
The code itself works great, but started throwing errors almost immediately when in production:
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')
The bulk of these errors seem to stem from having a problem calling the send_header() method where all I'm writing out is this:
self.send_header('Location', long_url)
So I'm curious where in my code to try to trap for this IO exception... do I write try/except calls around each of the self.send_header/self.end_headers/self.wfile.write calls? The other error I see from time to time is this one, but not sure which exception to watch to even catch this:
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')
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.
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)
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
来源：https://stackoverflow.com/questions/6063416/python-basehttpserver-how-do-i-catch-trap-broken-pipe-errors