Re: A problem while using urllib

Re: A problem while using urllib

[Steve Holden]

Steve Holden wrote:
> Johnny Lee wrote:
> [...]
> 
>>I've sent the source, thanks for your help.
>>
> 
> [...]
> Preliminary result, in case this rings bells with people who use urllib2 
> quite a lot. I modified the error case to report the actual message 
> returned with the exception and I'm seeing things like:
> 
> http://www.holdenweb.com/./Python/webframeworks.html
>     Message: <urlopen error (120, 'Operation already in progress')>
> Start process 
> http://www.amazon.com/exec/obidos/ASIN/0596001886/steveholden-20
> Error: IOError while parsing 
> http://www.amazon.com/exec/obidos/ASIN/0596001886/steveholden-20
>     Message: <urlopen error (120, 'Operation already in progress')>
>     .
>     .
>     .
> 
> So at least we know now what the error is, and it looks like some sort 
> of resource limit (though why only on Cygwin betas me) ... anyone, 
> before I start some serious debugging?
> 
I realized after this post that WingIDE doesn't run under Cygwin, so I 
modified the code further to raise an error and give us a proper 
traceback. I also tested the program under the standard Windows 2.4.1 
release, where it didn't fail, so I conclude you have unearthed a Cygwin 
socket bug. Here's the traceback:

End process http://www.holdenweb.com/contact.html
Start process http://freshmeat.net/releases/192449
Error: IOError while parsing http://freshmeat.net/releases/192449
    Message: <urlopen error (120, 'Operation already in progress')>
Traceback (most recent call last):
   File "Spider_bug.py", line 225, in ?
     spider.run()
   File "Spider_bug.py", line 143, in run
     self.grabUrl(tempUrl)
   File "Spider_bug.py", line 166, in grabUrl
     webPage = urllib2.urlopen(url).read()
   File "/usr/lib/python2.4/urllib2.py", line 130, in urlopen
     return _opener.open(url, data)
   File "/usr/lib/python2.4/urllib2.py", line 358, in open
     response = self._open(req, data)
   File "/usr/lib/python2.4/urllib2.py", line 376, in _open
     '_open', req)
   File "/usr/lib/python2.4/urllib2.py", line 337, in _call_chain
     result = func(*args)
   File "/usr/lib/python2.4/urllib2.py", line 1021, in http_open
     return self.do_open(httplib.HTTPConnection, req)
   File "/usr/lib/python2.4/urllib2.py", line 996, in do_open
     raise URLError(err)
urllib2.URLError: <urlopen error (120, 'Operation already in progress')>

Looking at that part of the course of urrllib2 we see:

         headers["Connection"] = "close"
         try:
             h.request(req.get_method(), req.get_selector(), req.data, 
headers)
             r = h.getresponse()
         except socket.error, err: # XXX what error?
             raise URLError(err)

So my conclusion is that there's something in the Cygwin socket module 
that causes problems not seen under other platforms.

I couldn't find any obviously-related error in the Python bug tracker, 
and I have copied this message to the Cygwin list in case someone there 
knows what the problem is.

Before making any kind of bug submission you should really see if you 
can build a program shorter that the existing 220+ lines to demonstrate 
the bug, but it does look to me like your program should work (as indeed 
it does on other platforms).

regards
  Steve
-- 
Steve Holden       +44 150 684 7255  +1 800 494 3119
Holden Web LLC                     www.holdenweb.com
PyCon TX 2006                  www.python.org/pycon/

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Re: A problem while using urllib

[Corinna Vinschen]

On Oct 12 09:57, Steve Holden wrote:
> I realized after this post that WingIDE doesn't run under Cygwin, so I 
> modified the code further to raise an error and give us a proper 
> traceback. I also tested the program under the standard Windows 2.4.1 
> release, where it didn't fail, so I conclude you have unearthed a Cygwin 
> socket bug. Here's the traceback:
> 
> End process http://www.holdenweb.com/contact.html
> Start process http://freshmeat.net/releases/192449
> Error: IOError while parsing http://freshmeat.net/releases/192449
>    Message: <urlopen error (120, 'Operation already in progress')>
> Traceback (most recent call last):
>   File "Spider_bug.py", line 225, in ?
>     spider.run()
>   File "Spider_bug.py", line 143, in run
>     self.grabUrl(tempUrl)
>   File "Spider_bug.py", line 166, in grabUrl
>     webPage = urllib2.urlopen(url).read()
>   File "/usr/lib/python2.4/urllib2.py", line 130, in urlopen
>     return _opener.open(url, data)
>   File "/usr/lib/python2.4/urllib2.py", line 358, in open
>     response = self._open(req, data)
>   File "/usr/lib/python2.4/urllib2.py", line 376, in _open
>     '_open', req)
>   File "/usr/lib/python2.4/urllib2.py", line 337, in _call_chain
>     result = func(*args)
>   File "/usr/lib/python2.4/urllib2.py", line 1021, in http_open
>     return self.do_open(httplib.HTTPConnection, req)
>   File "/usr/lib/python2.4/urllib2.py", line 996, in do_open
>     raise URLError(err)
> urllib2.URLError: <urlopen error (120, 'Operation already in progress')>
> 
> Looking at that part of the course of urrllib2 we see:
> 
>         headers["Connection"] = "close"
>         try:
>             h.request(req.get_method(), req.get_selector(), req.data, 
> headers)
>             r = h.getresponse()
>         except socket.error, err: # XXX what error?
>             raise URLError(err)
> 
> So my conclusion is that there's something in the Cygwin socket module 
> that causes problems not seen under other platforms.
> 
> I couldn't find any obviously-related error in the Python bug tracker, 
> and I have copied this message to the Cygwin list in case someone there 
> knows what the problem is.
> 
> Before making any kind of bug submission you should really see if you 
> can build a program shorter that the existing 220+ lines to demonstrate 
> the bug, but it does look to me like your program should work (as indeed 
> it does on other platforms).

Talking about a testcase, if you want to submit a bug report, could
you please apply a simple, self-contained, OOTB testcase, written in
plain C, which shows what's going on?  I just see an EINPROGRESS error
message above and I don't speak Python.  If this is something Cygwin
induced, then I see only two potential problems, both in connect(). 
Either a connect is called twice on a blocking socket, or a connection
fails and the error code is wrong for some reason.  A simple testcase
would help enormously.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat, Inc.

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Re: A problem while using urllib

[Steve Holden]

Corinna Vinschen wrote:
> On Oct 12 09:57, Steve Holden wrote:
[...]
> 
> Talking about a testcase, if you want to submit a bug report, could
> you please apply a simple, self-contained, OOTB testcase, written in
> plain C, which shows what's going on?  I just see an EINPROGRESS error
> message above and I don't speak Python.  If this is something Cygwin
> induced, then I see only two potential problems, both in connect(). 
> Either a connect is called twice on a blocking socket, or a connection
> fails and the error code is wrong for some reason.  A simple testcase
> would help enormously.
> 
Corinna:

Thanks for your note. This is actually johnny's problem, I was just 
helping him to locate the error. You might notice Jason Tishler was 
copied on my post, and I'm hoping he and Johnny will be able to isolate 
the problem.

regards
  Steve
-- 
Steve Holden       +44 150 684 7255  +1 800 494 3119
Holden Web LLC                     www.holdenweb.com
PyCon TX 2006                  www.python.org/pycon/

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