[twill] Temporary Failure in Name Resolution

Chris Abraham cabraham at openplans.org
Wed Apr 11 08:18:25 PDT 2007


Titus,
We've been doing some testing here which doesn't confirm what you've
been finding.

Test (1)

We installed the svn version of python 2.5 and ran the following twill test:
go http://www.google.com
...(repeated 1000 times)

meanwhile we tracked the open files on the computer with this:
while true; do /usr/sbin/lsof | grep twill | wc -l; sleep 1s; done

and found an output of:
180
226
275
332
...
999
1055

at which point the twill script fails with
Error:...'Temporary failure in name resolution'


Test (2)

We emulated this test using just python with this script:
import urllib2
for i in xrange(1000):
    f = urllib2.urlopen('http://www.google.com')

and tracked it with:
while true; do /usr/sbin/lsof | grep python | wc -l; sleep 1s; done

and found an output of:
387
387
...
387

with python 2.4 we get an output of:
315
341
368
395
308
308
322
344
(it flutters but otherwise remains stable around 340)



Conclusions:

urllib2 doesn't seem to be causing the problem.  Even with python 2.4,
Test(2) runs fine without an escalating number of open files.

We think that there is a problem in twill that for some reason creates
an escalating number of open files which eventually crashes the process.
 We will look into the twill code to try and find a solution.

Does this make sense?  What have been your findings?  We're not sure why
you think that the latest patched Python 2.5 fixes this problem.


Chris



Titus Brown wrote:
> > On Tue, Apr 10, 2007 at 12:10:56PM -0400, Chris Abraham wrote:
> > -> I've run into a problem with twill that has already been talked
about on
> > -> this list here:
> > -> http://thread.gmane.org/gmane.comp.web.twill/646/
> > ->
> > -> I get the same behavior in various different tests, that is, in a
long
> > -> test, after a certain length of time, twill consistently fails with:
> > -> Error message: '<urlopen error (-3, 'Temporary failure in name
> > -> resolution')>'
> > ->
> > -> Has anyone found a resolution to this problem?  I'm using twill
version
> > -> 0.9b1, and Python 2.4.3.
> >
> > Hey Chris,
> >
> > John Lee pointed me to a patch he submitted to Python,
> >
> > 	http://python.org/sf/1627441
> >
> > It was applied to 2.5 in January.  I realize this is a lot to ask,
> > but... could you try running using the latest Python svn?
> >
> > I can also send you a hacked version of twill that contains the updated
> > files for Python 2.5, so all you'd have to do is switch to using 2.5.
> > That's probably easier, eh?
> >
> > cheers,
> > --titus




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