Django Broken pipe in Debug mode

Question

I have django 1.3 on the remote server behind Nginx.

If I run django with apache + mod_wsgi, I can watch errors in apache log files. It's ok but I'd like to have in console.

If I run django own development server, I get errors with stacktrace in console only when DEBUG = False. In DEBUG mode console outputs

Exception happened during processing of request from (..., ...)
Traceback (most recent call last):
  File "/usr/local/python/lib/python2.7/SocketServer.py", line 284, in _handle_request_noblock
    self.process_request(request, client_address)
  File "/usr/local/python/lib/python2.7/SocketServer.py", line 310, in process_request
    self.finish_request(request, client_address)
  File "/usr/local/python/lib/python2.7/SocketServer.py", line 323, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/local/python/lib/python2.7/site-packages/django/core/servers/basehttp.py", line 570, in __init__
    BaseHTTPRequestHandler.__init__(self, *args, **kwargs)
  File "/usr/local/python/lib/python2.7/SocketServer.py", line 641, in __init__
    self.finish()
  File "/usr/local/python/lib/python2.7/SocketServer.py", line 694, in finish
    self.wfile.flush()
  File "/usr/local/python/lib/python2.7/socket.py", line 301, in flush
    self._sock.sendall(view[write_offset:write_offset+buffer_size])
error: [Errno 32] Broken pipe

I want to figure out why? Why does django just output unnamed Exception? Why does it depend on DEBUG variable.

This errors occurs mostly outside views when I have no access to request object. So I can't catch it in middleware or using logging handler.

UPDATE. I noticed if I request to django server directly I never get Broken pipe. So may the issue occur while Nginx proxy django?

Answer 1

This isn't really an issue with your site, more with the Django devserver: see this Django ticket. To put it bluntly, just ignore it as it is a known error, and won't be fixed.

In that ticket's comments a quite clear explanation is given:

According to many sources the 'Broken Pipe' is a normal browser quirk. For example, the browser reads from the socket and then decides that the image it's been reading apparently didn't change. The browser now this (forcefully) closes the connection because it does not need more data. The other end of this socket (the python runserver) now raises a socket exception telling the program that the client 'Broke the socket pipe'.

Answer 2

Nginx directive proxy_intercept_errors off; (disabled by default) is what I needed

Answer 3

Here is a way to prevent the to print the message to stderr. Just monkey patch the BaseServer.handle_error function. This is how I do it:

def patch_broken_pipe_error():
    """Monkey Patch BaseServer.handle_error to not write
    a stacktrace to stderr on broken pipe.
    https://stackoverflow.com/a/7913160"""
    import sys
    from SocketServer import BaseServer

    handle_error = BaseServer.handle_error

    def my_handle_error(self, request, client_address):
        type, err, tb = sys.exc_info()
        # there might be better ways to detect the specific erro
        if repr(err) == "error(32, 'Broken pipe')":
            # you may ignore it...
            logging.getLogger('mylog').warn(err)
        else:
            handle_error(self, request, client_address)

    BaseServer.handle_error = my_handle_error


patch_broken_pipe_error()

Answer 4

I was able to get rid of this by

proxy_buffering off;

This stops response buffering of proxied server. This leads to other issues of the back-end application being locked for long if the client is on a extremely slow connection.

To make it conditional for particular requests, use X-Accel-Buffering=no in the response header.

Answer 5

I fixed it. If you use links i.e, anchor tag, inside the page, you have to face the "Borken Pipe" problem. Just use inside the link tag href='#'. Don't leave the href attribute blank. It will avoid that type of error.

Answer 6

I came up with a quick and dirty monkey patch (i don't know if it supresses any useful errors), that gets rid of this annoying error when using "./manage.py runserver" or running LiveServerTestCase tests.

Just insert it anywhere in your code, where you need that:

# Monkeypatch python not to print "Broken Pipe" errors to stdout.
import SocketServer
from wsgiref import handlers
SocketServer.BaseServer.handle_error = lambda *args, **kwargs: None
handlers.BaseHandler.log_exception = lambda *args, **kwargs: None