[Python-bugs-list] [ python-Bugs-508157 ] urllib.urlopen results.readline is slow

[noreply@sourceforge.net]

Bugs item #508157, was opened at 2002-01-24 16:48
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=105470&aid=508157&group_id=5470

Category: Python Library
Group: Python 2.2
Status: Open
Resolution: None
Priority: 5
Submitted By: Keith Davidson (kbdavidson)
Assigned to: Nobody/Anonymous (nobody)
Summary: urllib.urlopen results.readline is slow

Initial Comment:
The socket file object underlying the return from 
urllib.urlopen() is opened without any buffering 
resulting in very slow performance of results.readline
().  The specific problem is in the 
httplib.HTTPResponse constructor.  It calls 
sock.makefile() with a 0 for the buffer size.  Forcing 
the buffer size to 4096 results in the time for 
calling readline() on a 60K character line to go from 
16 seconds to .27 seconds (there is other processing 
going on here but the magnitude of the difference is 
correct).

I am using Python 2.0 so I can not submit a patch 
easily but the problem appears to still be present in 
the 2.2 source.  The specific change is to change the 
0 in sock.makefile() to 4096 or some other reasonable 
buffer size:

class HTTPResponse:
    def __init__(self, sock, debuglevel=0):
        self.fp = sock.makefile('rb', 0)    <= change 
to 4096
        self.debuglevel = debuglevel



----------------------------------------------------------------------

>Comment By: A.M. Kuchling (akuchling)
Date: 2002-03-14 18:32

Message:
Logged In: YES 
user_id=11375

Greg Stein originally wrote it;  I'll ping him.

I suspect it might be because of 
HTTP pipelining; if multiple
responses will be returned over a socket, you 
probably can't use buffering because the buffer might consume the end of 
response #1 and the start of response #2.  


----------------------------------------------------------------------

Comment By: Guido van Rossum (gvanrossum)
Date: 2002-01-25 09:12

Message:
Logged In: YES 
user_id=6380

I wonder why the author explicitly turned off buffering.
There probably was a reason? Without knowing why, we can't
just change it.

----------------------------------------------------------------------

Comment By: Nobody/Anonymous (nobody)
Date: 2002-01-24 16:54

Message:
Logged In: NO 

What platform?

--Guido (not logged in)

----------------------------------------------------------------------

You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=105470&aid=508157&group_id=5470