Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #19033

Re: Hash stability

Path csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path <python-python-list@m.gmane.org>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.005
X-Spam-Evidence '*H*': 0.99; '*S*': 0.00; 'method,': 0.07; 'hits': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:80.91.229.12': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'received:lo.gmane.org': 0.09; 'output': 0.10; 'caching': 0.16; 'received:dip.t-dialin.net': 0.16; 'received:t-dialin.net': 0.16; 'stability.': 0.16; 'useless.': 0.16; 'wrote:': 0.16; 'appropriate': 0.22; 'runs': 0.23; 'from:addr:web.de': 0.23; 'cache': 0.24; 'code': 0.25; 'creating': 0.25; "wasn't": 0.25; 'fix': 0.27; "i'm": 0.27; 'around.': 0.28; 'worked': 0.29; 'problem': 0.29; 'broke': 0.30; 'hash': 0.30; '(the': 0.30; "didn't": 0.30; "i've": 0.31; 'actually': 0.32; 'thanks': 0.32; "isn't": 0.32; 'to:addr:python-list': 0.33; 'all.': 0.34; 'header:X-Complaints-To:1': 0.34; 'however,': 0.35; 'file': 0.35; 'entry': 0.37; 'machine': 0.37; 'but': 0.37; 'received:org': 0.37; 'using': 0.37; 'getting': 0.37; 'stable': 0.38; 'being': 0.39; 'hit': 0.39; 'subject:: ': 0.39; 'did': 0.39; 'change': 0.40; 'to:addr:python.org': 0.40; 'quick': 0.60; 'due': 0.66; 'production': 0.71; 'news': 0.73; 'migrating': 0.91; 'preferred,': 0.93
X-Injected-Via-Gmane http://gmane.org/
To python-list@python.org
From Peter Otten <__peter__@web.de>
Subject Re: Hash stability
Date Mon, 16 Jan 2012 09:18:48 +0100
Organization None
References <4f1107b7$0$29988$c3e8da3$5496439d@news.astraweb.com> <jeritr$4sb$1@dough.gmane.org> <4F1205A7.70303@modelnine.org> <jeu8t4$2kc$1@dough.gmane.org> <4F12BC8A.9040205@modelnine.org> <jeugdp$e1b$1@dough.gmane.org> <4F12F9D8.5080904@modelnine.org>
Mime-Version 1.0
Content-Type text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding 7Bit
X-Gmane-NNTP-Posting-Host p5084bea5.dip.t-dialin.net
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.12
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.4787.1326701934.27778.python-list@python.org> (permalink)
Lines 33
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1326701934 news.xs4all.nl 6982 [2001:888:2000:d::a6]:40394
X-Complaints-To abuse@xs4all.nl
Xref x330-a1.tempe.blueboxinc.net comp.lang.python:19033

Show key headers only | View raw

Heiko Wundram wrote:

> Am 15.01.2012 13:22, schrieb Peter Otten:

>> I'm curious: did you actually get false cache hits 

in a suds cache

>> or just slower responses?

> It broke the application using suds, not due to false cache hits, but
> due to not getting a cache hit anymore at all.

> so basically I worked around
> the problem by creating an appropriate cache entry with the appropriate
> name based on hash() using a local copy of xml.dtd I had around. This
> took place on a development machine (32-bit), and when migrating the
> application to a production machine (64-bit), the cache file wasn't used
> anymore (due to the hash not being stable).

Thanks for the explanation.

> if the hash() output is changed. Additionally, if hash() isn't stable
> between runs (the randomized hash() solution which is preferred, and
> would also be my preference), suds caching becomes completely useless.
> And for the results, see above.

I've taken a quick look into the suds source; the good news is that you have 
to change a single method, reader.Reader.mangle(), to fix the problem with 
hash stability. 

However, I didn't see any code to deal with hash collisions at all.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Hash stability Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-14 04:42 +0000
  Re: Hash stability Peter Otten <__peter__@web.de> - 2012-01-14 10:46 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-14 23:45 +0100
  Re: Hash stability Chris Angelico <rosuav@gmail.com> - 2012-01-15 11:36 +1100
    Re: Hash stability Bryan <bryanjugglercryptographer@yahoo.com> - 2012-01-15 04:03 -0800
      Re: Hash stability Chris Angelico <rosuav@gmail.com> - 2012-01-15 23:21 +1100
  Re: Hash stability Roy Smith <roy@panix.com> - 2012-01-14 21:26 -0500
    Re: Hash stability Terry Reedy <tjreedy@udel.edu> - 2012-01-14 23:07 -0500
  Re: Hash stability Stefan Behnel <stefan_ml@behnel.de> - 2012-01-15 11:13 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-15 12:46 +0100
  Re: Hash stability Peter Otten <__peter__@web.de> - 2012-01-15 13:22 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-15 17:07 +0100
  Re: Hash stability Chris Angelico <rosuav@gmail.com> - 2012-01-16 03:13 +1100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-15 17:51 +0100
  Re: Hash stability Stefan Behnel <stefan_ml@behnel.de> - 2012-01-15 18:20 +0100
  Re: Hash stability Peter Otten <__peter__@web.de> - 2012-01-16 09:18 +0100
  Re: Hash stability Christian Heimes <lists@cheimes.de> - 2012-01-16 09:44 +0100
  Re: Hash stability Heiko Wundram <modelnine@modelnine.org> - 2012-01-16 10:15 +0100

csiph-web