Mailman 3 May 2011 - Python-Dev

Re: [Python-Dev] [Python-checkins] Daily reference leaks (234021dcad93): sum=61
by Nick Coghlan 25 May '11

25 May '11

On Wed, May 25, 2011 at 1:09 PM, <solipsis(a)pitrou.net> wrote: > results for 234021dcad93 on branch "default" > -------------------------------------------- > > test_packaging leaked [128, 128, 128] references, sum=384 Is there a new cache in packaging that regrtest needs to know about and either ignore or clear when checking reference counts? Cheers, Nick. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

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[pyodbc] Setting values to SQL_* constants while creating a connection object
by srinivasan munisamy 24 May '11

24 May '11

Hi, I would like to know how to set values to values to SQL_* constants while creatinga db connection through pyodbc module. For example, i am getting a connection object like below: In [27]: dbh1 = pyodbc.connect("DSN=<dsn>;UID=<uid>;PWD=<pwd>;DATABASE=<database>;APP=<app_name>") In [28]: dbh1.getinfo(pyodbc.SQL_DESCRIBE_PARAMETER) Out[28]: True I want to set this SQL_DESCRIBE_PARAMETER to false for this connection object. How could i do that? Please help me in figuring it out. Thanks, Srini

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CPython optimization: storing reference counters outside of objects
by Artur Siekielski 24 May '11

24 May '11

Hi. The problem with reference counters is that they are very often incremented/decremented, even for read-only algorithms (like traversal of a list). It has two drawbacks: 1. CPU cache lines (64 bytes on X86) containing a beginning of a PyObject are very often invalidated, resulting in loosing many chances to use the CPU caches 2. The copy-on-write after fork() optimization (Linux) is almost useless in CPython, because even if you don't modify data directly, refcounts are modified, and PyObjects with refcounts inside are spread all over process' memory (and one small refcount modification causes the whole page - 4kB - to be copied into a child process). So an idea I would like to try is to move reference counts outside of PyObjects, to a contiguous block(s) of memory. PyObjects would have a pointer to a reference count inside this block. Doing this I think that 1. The beginning of PyObject structs could be CPU-cached for a much longer time (small objects like ints could be fully cached). I don't know if having localized writes into the block with refcounts also help performance? 2. copy-on-write after fork() will work much better, only the block with refcounts would be copied into a child process (for read-only algorithms) However the drawback is that such design introduces a new level of indirection which is a pointer inside a PyObject instead of a direct value. Also it seems that the "block" with refcounts would have to be a non-trivial data structure. I'm not a compiler/profiling expert so the main question is if such design can work, and maybe someone was thinking about something similar? And if CPython was profiled for CPU cache usage?

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Stable buildbots update
by Antoine Pitrou 24 May '11

24 May '11

Hello, We recently got a couple of new stable buildbots: - R. David Murray's "x86 Gentoo" machine, which builds in non-debug mode and therefore checks that release Pythons work fine - Stefan Krah's "AMD64 FreeBSD 8.2" machine - Bill Janssen's "AMD64 Snow Leopard" machine Many stable buildbots on the default branch (*) are currently red because of test_packaging issues. (*) http://www.python.org/dev/buildbot/all/waterfall?category=3.x.stable Regards Antoine.

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Re: [Python-Dev] cpython: move specialized dir implementations into __dir__ methods (closes #12166)
by Georg Brandl 24 May '11

24 May '11

On 24.05.2011 18:08, benjamin.peterson wrote: > http://hg.python.org/cpython/rev/8f403199f999 > changeset: 70331:8f403199f999 > user: Benjamin Peterson <benjamin(a)python.org> > date: Tue May 24 11:09:06 2011 -0500 > summary: > move specialized dir implementations into __dir__ methods (closes #12166) > +static PyMethodDef module_methods[] = { > + {"__dir__", module_dir, METH_NOARGS, > + PyDoc_STR("__dir__() -> specialized dir() implementation")}, > + {0} > +}; > static PyMethodDef type_methods[] = { > {"mro", (PyCFunction)mro_external, METH_NOARGS, > PyDoc_STR("mro() -> list\nreturn a type's method resolution order")}, > @@ -2585,6 +2661,8 @@ > PyDoc_STR("__instancecheck__() -> check if an object is an instance")}, > {"__subclasscheck__", type___subclasscheck__, METH_O, > PyDoc_STR("__subclasscheck__() -> check if a class is a subclass")}, > + {"__dir__", type_dir, METH_NOARGS, > + PyDoc_STR("__dir__() -> specialized __dir__ implementation for types")}, > static PyMethodDef object_methods[] = { > {"__reduce_ex__", object_reduce_ex, METH_VARARGS, > PyDoc_STR("helper for pickle")}, > @@ -3449,6 +3574,8 @@ > PyDoc_STR("default object formatter")}, > {"__sizeof__", object_sizeof, METH_NOARGS, > PyDoc_STR("__sizeof__() -> size of object in memory, in bytes")}, > + {"__dir__", object_dir, METH_NOARGS, > + PyDoc_STR("__dir__() -> default dir() implementation")}, This is interesting: I though we use "->" to specify the return value (or its type). __instancecheck__ and __subclasscheck__ set a different precedent, while __sizeof__ follows. I didn't look at the files to check for other examples. Georg

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Re: [Python-Dev] cpython: Issue #11377: platform.popen() emits a DeprecationWarning
by Georg Brandl 24 May '11

24 May '11

On 24.05.2011 00:17, victor.stinner wrote: > http://hg.python.org/cpython/rev/e44b851d0a2b > changeset: 70323:e44b851d0a2b > parent: 70321:202d973e8bf5 > user: Victor Stinner <victor.stinner(a)haypocalc.com> > date: Tue May 24 00:16:16 2011 +0200 > summary: > Issue #11377: platform.popen() emits a DeprecationWarning Please see http://mail.python.org/pipermail/python-dev/2011-May/111303.html about the style of your commit messages. 9a16fa0c9548 is another example. Georg

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the distutils2 repo and 3to2
by Tarek Ziadé 23 May '11

23 May '11

Hey, Now that packaging has landed, the distutils2 repo is going to be re-seted and will be the python 2.x / 3.1 / 3.2 backport of packaging. In theory, we want to automate the extraction of packaging from the stdlib and a few other modules, and run 3to2 at install time. Or should I say 3.3tosomething. I want to do this to avoid maintaining yet another code base. In practice, I don't really know the current state of 3to2 so we'll see.. Any help/hint in this project would be appreciated. Thanks Tarek -- Tarek Ziadé | http://ziade.org

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looking for a contact at Google on the Blogger team
by Doug Hellmann 23 May '11

23 May '11

Several of the PSF blogs hosted on Google's Blogger platform are experiencing issues as fallout from the recent maintenance problems they had. We have already had to recreate at least one of the translations for Python Insider in order to be able to publish to it, and now we can't edit posts on Python Insider itself. Can anyone put me in contact with someone at Google from the Blogger team? I would at least like to know whether the "bX-qpvq7q" problem is being worked on, so I can decide whether to take a hiatus or start moving us to another platform. There are a lot of posts about the error on the support forums, but no obvious response from Google. Thanks, Doug -- Doug Hellmann Communications Director Python Software Foundation http://python.org/psf/

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os.access on Windows
by Tim Golden 23 May '11

23 May '11

There's a thread on python-list at the moment: http://mail.python.org/pipermail/python-list/2011-May/1272505.html which is discussing the validity of os.access results on Windows. Now we've been here before: I raised issue2528 for a previous enquiry some years ago and proffered a patch which uses the AccessCheck API to perform the equivalent check, but didn't follow through. Someone on the new thread is suggesting -- validly -- that the docs should highlight the limitations of this call on Windows. But the docs for that call are already fairly involved: http://docs.python.org/library/os.html#os.access We seem to have a few options in increasing order of difficulty: * Do nothing - inform the occasional enquirer of the situation and leave it at that. * Update the docs to add something which describes what the function actually does on the Windows platform. (Whether or not we change any code). * Apply the patch in issue2528 to 3.3 and maybe 2.7 * Leave os.access alone but offer alternative Windows-specific functionality in the os module or elsewhere, using essentially the code in the issue2528 patch. As a side note, the pywin32 packages don't actually include AccessCheck at the moment. (Which makes it slightly harder to explain to people how they could do this check for themselves). It could probably be added over there which might ease the burden over here. Opinions? TJG Tim Golden Very Senior Analyst Programmer CBS Outdoor UK Camden Wharf 28 Jamestown Road London NW1 7BY T: 020 7482 3000 F: 020 7267 4944 http://www.cbsoutdoor.co.uk/ http://www.cbsoutdoor.co.uk/ http://www.bigbuschallenge.com/ Don't waste paper. Think before you print. The contents of this e-mail are confidential to the ordinary user of the e-mail address to which it was addressed, and may also be privileged. If you are not the addressee of this e-mail you may not copy, forward, disclose or otherwise use it or any part of it in any form whatsoever. If you have received this e-mail in error, please e-mail the sender by replying to this message. CBS Outdoor Ltd reserves the right to monitor e-mail communications from external/internal sources for the purposes of ensuring correct and appropriate use of CBS Outdoor facilities. CBS Outdoor Limited, registered in England and Wales with company number 02866133 and registered address at Camden Wharf, 28 Jamestown Road, London, NW1 7BY. ________________________________________________________________________ This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________

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Hello!
by Charles-François Natali 23 May '11

23 May '11

Hi, My name is Charles-François Natali, I've been using Python for a couple years, and I've recently been granted commit priviledge. I just wanted to say hi to everyone on this list, and let you know that I'm really happy and proud of joining this great community. Cheers, cf

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