homepage

Occasionally, the isclosed() method of HTTPResponse instances returns False, even though a preceding read() call returned '' (or something else that evalues to False).
This is a problem, because then the corresponding HTTPConnection can still be used to send another request, but an attempt to retrieve its response result it in ResponseNotReady() exception.
I have not found anything special about the requests for which this happens. I also looked at the httplib code and found no way for this to happen, but obviously I am missing something. Maybe someone more familiar with the codebase can tell what's happening there.
The problem happens to rarely to be able to run packet capture, but I can provide attributes of the relevant httplib instances if desired.

Without a reproducible test case I doubt we are going to be able to solve this, but yes please provide what information you can for the record, in case someone else runs in to it in a more reproducible situation.

The problem seems to occur regularly, just with large intervals in between. Is there any specific information that might help here? I am not quite sure what to save when the problem happens the next time. Can the response object be pickled?

Do you call read() or read(<some length>)?
Please inspect at least the "fp", "length", "chunked" and "chunk_left" attributes.

The call should be read(size), with size a number. I will make sure to check size, "fp", "length", "chunked" and "chunk_left" when it happens the next time.

This is just a heads-up that I'm still trying to debug this. So far, the problem doesn't seem to have shown up again (for reference, the original report for this is http://code.google.com/p/s3ql/issues/detail?id=358).

@Nikolaus
Issue 16298 was raised today describing what could be the cause of what you observe.

Alright, it *finally* happened again.
Attributes of the response object are:
._method: GET, 
.chunked: 0, 
.length: 9369540
.chunk_left: UNKNOWN, 
.status: 200 
.reason "OK", 
.version: 11, 
.will_close: False

"length: 9369540" indicates you haven't read the whole advertised Content-Length. Is it possible the server shuts down the TCP connection even before the whole Content-Length has been sent?

Here is a patch for 2.7.
Ideally, we would raise IncompleteRead in this situation, but this would break existing programs.

New changeset 8dcf94c2fef5 by Antoine Pitrou in branch '2.7':
Issue #15633: httplib.HTTPResponse is now mark closed when the server sends less than the advertised Content-Length.
http://hg.python.org/cpython/rev/8dcf94c2fef5 

New changeset 03c536afeb7e by Antoine Pitrou in branch '3.2':
Issue #15633: httplib.HTTPResponse is now mark closed when the server sends less than the advertised Content-Length.
http://hg.python.org/cpython/rev/03c536afeb7e
New changeset 7d504068bc58 by Antoine Pitrou in branch '3.3':
Issue #15633: httplib.HTTPResponse is now mark closed when the server sends less than the advertised Content-Length.
http://hg.python.org/cpython/rev/7d504068bc58
New changeset 9f9287357af9 by Antoine Pitrou in branch 'default':
Issue #15633: httplib.HTTPResponse is now mark closed when the server sends less than the advertised Content-Length.
http://hg.python.org/cpython/rev/9f9287357af9 

I've committed the patch into 2.7 and then ported it to 3.x. Please reopen if the problem still occurs with the patch.

On 01/29/2013 11:23 PM, Antoine Pitrou wrote:
> "length: 9369540" indicates you haven't read the whole advertised Content-Length. Is it possible the server shuts down the TCP connection even before the whole Content-Length has been sent?
The remote server isn't under my control, so I can't say for sure. But I
guess the connection could be terminated prematurely for quite a number
of reasons, so if that causes trouble for httplib then this might well
be the problem.
Best,
 -Nikolaus
-- 
 »Time flies like an arrow, fruit flies like a Banana.«
 PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C