Canonical Voices

pitti

Part of our efforts to reduce power consumption in Ubuntu is to provide an easy tool to hunt down which programs and devices are to blame for inordinate power consumption. powertop’s interactive mode is pretty good for this if you are sitting in a train and want to tweak some knobs to max out battery life, but we need something more reproducible and noninteractive for developers who want to file proper bug reports.

So I wrote a little script power-usage-report which calls fatrace for measuring file access activity from programs, and powertop-1.13 to measure process and device wakeups, clean up and sort their ouput, and generate a report which is appropriate to attach to bug reports, send around, put into Jenkins for measuring daily progress, etc. It is now part of fatrace version 0.4, so today’s Precise upgrades will have it.

The output has several sections for disk access (which prevent the disk from spinning down), wakeups (causing CPU power usage), and device activity. Disk/wakeups are sorted in descending order by process:

$ sudo power-usage-report
Measurement will begin in 5 seconds. Please make sure that the
computer is idle, i. e. do not press keys, start or operate programs, and that
programs are not busy with active tasks other than the one you want to examine.
Starting measurement for 60 seconds...
Measurement complete. Generating report...
======= unity-panel-ser: 5 file access events ======
/usr/share/zoneinfo/UTC: 1 reads
/etc/timezone:
/usr/share/zoneinfo/posix/Europe/Berlin: 1 reads
/etc/localtime: 3 reads

======= gnome-settings-: 1 file access events ======
/etc/fstab: 1 reads

======= telepathy-gabbl: 1 file access events ======
/home/martin/.cache/wocky/caps/caps-cache.db: 1 reads

====== Wakeups ======
  30,9% ( 52,0)   compiz
  16,3% ( 27,4)   [iwlwifi] 
  12,5% ( 21,0)   [i915] 
   3,7% (  6,3)   [ahci] 
   2,3% (  3,9)   swapper/3
   1,2% (  2,0)   gvfs-afc-volume
[...]

====== Devices ======
An audio device is active 100,0% of the time:
hwC0D0 Conexant CX20585 

Recent USB suspend statistics
Active  Device name
100,0%	USB device 1-1.5.4.4 : USB Mouse (A4Tech)
100,0%	/sys/bus/usb/devices/1-1.5.4.2
100,0%	USB device 1-1.5.4 : Kinesis Keyboard Hub (PI Engineering)
  0,0%	USB device 1-1.5.2 : USB2.0 Hub Controller (NEC Corporation)

[...]

You can redirect output to a file, of course. The top header (“Starting measurement..” etc.) will go to stderr and thus not be part of the redirected output.

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pitti

Part of our efforts to reduce power consumption is to identify processes which keep waking up the disk even when the computer is idle. This already resulted in a few bug reports (and some fixes, too), but we only really just began with this.

Unfortunately there is no really good tool to trace file access events system-wide. powertop claims to, but its output is both very incomplete, and also wrong (e. g. it claims that read accesses are writes). strace gives you everything you do and don’t want to know about what’s going on, but is per-process, and attaching strace to all running and new processes is cumbersome. blktrace is system-wide, but operates at a way too low level for this task: its output has nothing to do any more with files or even inodes, just raw block numbers which are impossible to convert back to an inode and file path.

So I created a little tool called fatrace (“file access trace”, not “fat race” :-) ) which uses fanotify, a couple of /proc lookups and some glue to provide this. By default it monitors the whole system, i. e. all mounts (except the virtual ones like /proc, tmpfs, etc.), but you can also tell it to just consider the mount of the current directory. You can write the log into a file (stdout by default), and run it for a specified number of seconds. Optional time stamps and PID filters are also provided.

$ sudo fatrace
rsyslogd(967): W /var/log/auth.log
notify-osd(2264): O /usr/share/pixmaps/weechat.xpm
compiz(2001): R device 8:2 inode 658203
[...]

It shows the process name and pid, the event type (Rread, Write, Open, or Close), and the path. Sometimes its’ not possible to determine a path (usually because it’s a temporary file which already got deleted, and I suspect mmaps as well), in that case it shows the device and inode number; such programs then need closer inspection with strace.

If you run this in gnome-terminal, there is an annoying feedback loop, as gnome-terminal causes a disk access with each output line, which then causes another output line, ad infinitum. To fix this, you can either redirect output to a file (-o /tmp/trace) or ignore the PID of gnome-terminal (-p `pidof gnome-terminal`).

So to investigate which programs are keeping your disk spinning, run something like

  $ sudo fatrace -o /tmp/trace -s 60

and then do nothing until it finishes.

My next task will be to write an integration program which calls fatrace and powertop, and creates a nice little report out of that raw data, sorted by number of accesses and process name, and all that. But it might already help some folks as it is right now.

The code lives in bzr branch lp:fatrace (web view), you can just run make and sudo ./fatrace. I also uploaded a package to Ubuntu Precise, but it still needs to go through the NEW queue. I also made a 0.1 release, so you can just grab the release tarball if you prefer. Have a look at the manpage and --help, it should be pretty self-explanatory.

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pitti

PackageKit has a “WhatProvides” API for mapping distribution independent concepts to particular package names. For example, you could ask “which packages provide a decoder for AC3 audio files?

$ pkcon what-provides  "gstreamer0.10(decoder-audio/ac3)"
[...]
Installed   	gstreamer0.10-plugins-good-0.10.30.2-2ubuntu2.amd64	GStreamer plugins from the "good" set
Available  	gstreamer0.10-plugins-ugly-0.10.18-3ubuntu4.amd64	GStreamer plugins from the "ugly" set

This is the kind of question your video player would ask the system if it encounters a video it cannot play. In reality they of course use the D-BUS or the library API, but it’s easier to demonstrate with the PackageKit command line client.

PackageKit provides a fair number of those concepts; I recently added LANGUAGE_SUPPORT for packages which provide dictionaries, spell checkers, and other language support for a given language or locale code.

However, PackageKit’s apt backend does not actually implement a lot of these (only CODEC and MODALIAS), and aptdaemons’s PackageKit compatibility API does not implement any. That might be because their upstreams do not know enough how to do the mapping for a particular distro/backend, because doing so involves distro specific code which should not go into upstreams, or simply because of the usual chicken-egg problem of app developers rather doing their own thing instead of using generic APIs.

So this got discussed between Sebastian Heinlein and me, and voila, there it is: it is now very easy to provide Python plugins for “what-provides” to implement any of the existing types. For example, language-selector now ships a plugin which implements LANGUAGE_SUPPORT, so you can ask “which packages do I need for Chinese in China” (i. e. simplified Chinese)?

$ pkcon what-provides "locale(zh_CN)"
[...]
Available   	firefox-locale-zh-hans-10.0+build1-0ubuntu1.all	Simplified Chinese language pack for Firefox
Available   	ibus-sunpinyin-2.0.3-2.amd64            	sunpinyin engine for ibus
Available   	language-pack-gnome-zh-hans-1:12.04+20120130.all	GNOME translation updates for language Simplified Chinese
Available   	ttf-arphic-ukai-0.2.20080216.1-1.all    	"AR PL UKai" Chinese Unicode TrueType font collection Kaiti style
[...]

Rodrigo Moya is currently working on implementing the control-center region panel redesign in a branch. This uses exactly this feature.

In Ubuntu we usually do not use PackageKit itself, but aptdaemon and its PackageKit API compatibility shim python-aptdaemon.pkcompat. So I ported that plugin support for aptdaemon-pkcompat as well, so plugins work with either now. Ubuntu Precise got the new aptdaemon (0.43+bzr769-0ubuntu1) and language-selector (0.63) versions today, so you can start playing around with this now.

So how can you write your own plugins? This is a trivial, although rather nonsense example:

from packagekit import enums

def my_what_provides(apt_cache, provides_type, search):
    if provides_type in (enums.PROVIDES_CODEC, enums.PROVIDES_ANY):
        return [apt_cache["gstreamer-moo"]]
    else:
        raise NotImplementedError('cannot handle type ' + str(provides_type))

The function gets an apt.Cache object, one of enums.PROVIDES_* and the actual search type as described in the documentation (above dummy example does not actually use it). It then decides whether it can handle the request and return a list of apt.package.Package objects (i. e. values in an apt.Cache map), or raise a NotImplementedError otherwise.

You register the plugin through Python pkg-resources in your setup.py (this needs setuptools):

   setup(
       [....]

       entry_points="""[packagekit.apt.plugins]
what_provides=my_plugin_module_name:my_what_provides
""",
       [...])

You can register arbitrarily many plugins, they will be all called and their resulting package lists joined.

All this will hopefully help a bit to push distro specifics to the lowest possible levels, and use upstream friendly and distribution agnostic APIs in your applications.

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pitti

Suppose you install Ubuntu and select a language other than English (it’s known to happen!). This will install the general and the GNOME language packs, translated LibreOffice help, and so on. Now, install a KDE package or GIMP. You’ll notice that the new application is not translated and has no help available for your language. The next time you open the language selector from control-center it would tell you that you miss some language support and offer to install it, but this has been pretty indiscoverable, and we really can do better.

Today’s language-selector upload provides an aptdaemon plugin which automatically marks corresponding language support packages (translated help, dictionaries, spell checker modules, and translations themselves) for installation for any newly installed package, for all languages that are configured on your system.

For example, I have German and English locales on my system, and no KDE packages. Before, installing GIMP got me just that:

$ aptdcon -i gimp
The following NEW package will be installed (1):
gimp

Now it automatically installs the corresponding localized help:


$ aptdcon -i gimp
The following NEW packages will be installed (4):
gimp gimp-help-common gimp-help-de gimp-help-en

I am using aptdcon here as it points out the effect better than software-center doing all this in the background, but both use aptdaemon, so the effect will be the same.

Likewise, installing the first KDE-ish package will automatically install the KDE language packs:


$ aptdcon -i kate
The following NEW packages will be installed (71):
kate kate-data [...] kdelibs5-data [...] language-pack-kde-de language-pack-kde-en [...]

This is now possible because I rewrote the check-language-support logic from scratch; the old code was very slow, hard to read and a nightmare to maintain, and also depended on a lot of data files. The new code is very fast (figuring out all missing language support packages for all installed packages for all available locales takes 8 ms on my system), and has full test coverage.

While the check-language-support program still works (I rewrote it using the new API), it is easier and probably a lot faster to just use the new API now, e. g. in our Ubiquity installer.

Say goodbye to this 2.5 year old bug!

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pitti

On my 8 hour train ride to Budapest last Sunday I finally worked on making libxklavier introspectable. Thanks to Sergey’s fast review the code now landed in trunk. I sent a couple of refinements to the bug report still, but those are mostly just icing on the cake, the main functionality of getting and setting keyboard layouts is working nicely now (see the example script).

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pitti

I’m the release engineer in charge for Precise Alpha 1 which is currently being prepared. I must say, this has been a real joy! The fruits of the new QA paradigm and strategy and the new Stable+1 maintenance team have already achieved remarkable results:

  • The archive consistency reports like component-mismatches, uninstallability, etc. now appear about 20 minutes earlier than in oneiric.
  • CD image builds can now happen 30 minutes earlier after the publisher start, and are much quicker now due to moving to newer machines. We can now build an i386 or amd64 CD image in 8 minutes! Currently they still need to wait for the slow powerpc buildd, but moving to a faster machine there is in progress. These improvements lead to much faster image rebuild turnarounds.
  • Candidate CDs now get automatically posted to the new ISO tracker as soon as they appear.
  • Whenever a new Ubuntu image is built (daily or candidate), they automatically get smoke-tested, so we know that the installer works under some standard scenarios and produces an install which actually boots.
  • Due to the new discipline and the stable+1 team, we had working daily ISOs pretty much every day. In previous Alphas, the release engineer(s) pretty much had to work fulltime for a day or two to fix the worst uninstallability etc., all of this now went away.

All this meant that as a release engineer almost all of the hectic and rather dull work like watching for finished ISO builds and posting them or getting the archive into a releasable state completely went away. We only had to decide when it was a good time for building a set of candidate images, and trigger them, which is just copy&pasting some standard commands.

So I could fully concentrate on the interesting bits like actually investigating and debugging bug reports and regressions. As the Law of Conservation of Breakage dictates, taking away work from the button pushing side just caused the actual bugs to be much harder and earned us e. g. this little gem which took Jean-Baptiste, Andy, and me days to even reproduce properly, and will take much more to debug and fix.

In summary, I want to say a huge “Thank you!” to the Canonical QA team, in particular Jean-Baptiste Lallement for setting up the auto-testing and Jenkins integration, and the stable+1 team (Colin Watson, Mike Terry, and Mathieu Trudel-Lapierre in November) for keeping the archive in such excellent shape and improving our tools!

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pitti

Apport and the retracer bot in the Canonical data center have provided server-side automatic closing of duplicate crash report bugs for quite a long time. As we have only kept Apport crash detection enabled in the development release, we got away with this as bugs usually did not get so many duplicates that they became unmanageable. Also, the number of duplicates provided a nice hint to how urgent and widespread a crash actually was.

However, it’s time to end that era and provide something better now:

  • This probably caused a lot of frustration when a reporter of the crash spent time, bandwidth, and creativity to upload the crash data and create a description for it, only to find that it got closed as a duplicate 20 minutes later.
  • Some highly visible crashes sometimes generated up to a hundred duplicates in Launchpad, which was prone to timeouts, and needless catch-up by the retracers.
  • We plan to have a real crash database soon, and eventually want to keep Apport enabled in stable releases. This will raise the number of duplicates that we get by several magnitudes.
  • For common crashes we had to write manual bug patterns to avoid getting even more duplicates.

So with the just released Apport 1.90 we introduce client-side duplicate checking. So from now, when you report a crash, you are likely to see “We already know about this” right away, without having to upload or type anything, and you will get directed to the bug page. You should mark yourself as affected and/or subscribe to the bug, both to get a notification when it gets fixed, and also to properly raise the “hotness” of the bug to bubble up to developer attention.

For the technically interested, this is how we detect duplicates for the “signal” crashes like SIGSEGV (as opposed to e. g. Python crashes, where we always have a fully symbolic stack trace):
As we cannot rely on symbolic stack traces, and do not want to force every user to download tons of debug symbols, Apport now falls back to generating a “crash address signature” which combines the absolute addresses of the (non-symbolic) stack trace and the /proc/pid/maps mapping to a stack of libraries and the relative offsets within those, which is stable under ASLR for a given set of dependency versions. As the offsets are specific to the architecture, we form the signature as combination of the executable name, the signal number, the architecture, and the offset list. For example, the i386 signature of bug looks like this:

/usr/bin/rhythmbox:11:i686:/usr/lib/libgstpbutils-0.10.so.0.24.0+c284:/usr/lib/i386-linux-gnu/libgobject-2.0.so.0.3000.0+3337a:/usr/lib/i386-linux-gnu/libgobject-2.0.so.0.3000.0+8e0

As library dependencies can change, we have more than one architecture, and the faulty function can be called from different entry points, there can be many address signatures for a bug, so the database maintains an N:1 mapping. In its current form the signatures are taken as-is, which is much more strict than it needs to be. Once this works in principle, we can refine the matching to also detect duplicates from different entry points by reducing the part that needs to match to the common prefix of several signatures which were proven to be a duplicate by the retracer (which gets a fully symbolic stack trace).

The retracer bots now exports the current duplicate/address signature database to http://people.canonical.com/~ubuntu-archive/apport-duplicates in an indexed text format from where Apport clients can quickly check whether a bug is known.

For the Launchpad crash database implementation we actually check if the bug is readable by the reporter, i. e. it is private and the reporter is in a subscribed team, or the bug is public; if not, we let him report the bug anyway and duplicate it later through the existing server-side retracer, so that the reporter has a chance of getting subscribed to the bug. We also let the bug be filed if the currently existing symbolic stack trace is bad (tagged as apport-failed-retrace) or if a developer wants a new symbolic stack trace with the current libraries (tagged as apport-request-retrace).

As this is a major new feature, I decided that it’s time to call this Apport 2.0. This is the first public beta towards it, thus called 1.90. With Apport’s test driven and agile development the version numbers do not mean much anyway (the retracer bots in the data center always just run trunk, for example), so this is as good time as any to reset the rather large “.26″ minor version that we are at right now.

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pitti

12.04: Testing FTW

I arrived back home in Augsburg, from last week’s Ubuntu Developer Summit in Orlando, FL. As this is a quality/LTS cycle, we pretty much already knew in advance what to do (bug fixing, bug fixing, some boot speed, and did I mention bug fixing?), but still we had many highly interesting and exciting sessions this time, not so much about what we are going to do, but how we are going to build 12.04.

So far our common practice has been to toss everything new into the development release until Feature Freeze and then try and clean up most of the fallout. Me and many other developers have always cried for having more time for fixing long-standing bugs and not introducing breakage in the first place. It seems that now with 12.04, Ubuntu/Canonical are actually getting serious about it.

(Any resemblance to that postcard from the Kennedy Space Center which I went to last Sunday is of course absolutely unintended and purely coincidental :-) ).

The mission statement is now to have working ISOs, stable ? development, and daily intra-development upgrades every day, quick and regular cleanup of uninstallable packages, component-mismatches, NBS etc., backed by a new “stable +1″ team backed by three people on a rotational shift.

QA team is now setting up daily automatic smoketesting of the installer and other packages which have tests. For the latter we’ll convert some packages to the DEP-8, the proposed format for running autopkgtest on (I’ll do udisks, postgresql-common, pygobject, apport, and jockey soon).

We’ll try do put uploads which might break something (like new libraries) to a staging area first, against which we can run test suites of reverse dependencies before it lands in the new release. As doing this on a large scale still requires infrastructure to be created, we’ll only exercise it for a few packages by uploading to precise-proposed first, but this has a high potential for extension.

We want to commit to fixing major breakage within 3 hours of development time, or otherwise revert the faulty package to the previous version (unless that aggravates problems, such as file conflicts).

Finally, for Canonical upstreams we are introducing “acceptance criteria”, which will hopefully significantly raise the quality and lower the regressions of each Unity etc. release.

So, the mission is clear. In practice we’ll probably have to make some real-life concessions, and Murphy’s law dictates that there still will be some breakage, but we can learn from that as we go.

Let’s build 12.04 LTS!

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pitti

Just took the plunge, using the excellent bandwidth and local mirror at UDS:

$ lsb_release -irc
Distributor ID: Ubuntu
Release: 12.04
Codename: precise

Nothing blew up in my face, so it seems today is a good day to die^Wupgrade.

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pitti

On a rather calm ten-hour flight to Orlando I once again did some pygobject, udisks, and Apport hacking (It’s scary how productive one can be when not constantly being interrupted by IRC, email, etc). One more visible change amongst these was finally fixing a five year old five-digit bug to integrate apport-retrace into the GUI, now that it does not potentially wreck your installation any more.

If the apport-retrace package is installed, the crash detail dialog will show a new “Examine locally” button:

Apport crash detail dialog

After clicking this, you can choose what do do exactly:

Retrace action dialog

I know this dialog is not a beauty, as it’s implemented using the ui_question_choice() API which is used by package hooks. That makes it work for all available UIs (GTK, KDE, CLI), though, and can easily be extended to have more actions. And if you get this far and want to stack traces, you are used to looking at eye-bleeding gibberish anyway..

Presumably the most useful (and default) action is to download all the debug symbols, open a Terminal, and put you into a GDB session with all these, and the core dump loaded, so that you can poke around the crashed program state with all symbols available.

But you can also run gdb without downloading debug symbols, or just update the .crash report file with a fully symbolic stack trace.

This works just as well in apport-cli, but not yet in the KDE version: Someone needs to implement the equivalent of the apport-gtk implementation to apport-kde and kde/bugreport.ui, i. e. show an “Examine locally” button if self.can_examine_locally() is true, and add an appropriate ui_run_terminal() method (which should be fairly similar to the GTK one, just with Qt/KDEish terminal emulators). But as Kubuntu does not currently use Apport (and also because I didn’t have all the dependencies installed on my laptop) I did not yet do this. Please catch me on IRC/mail/merge proposal if you want to work on this. If you look at above commit, the changes to the GtkBuilder file look huge, but that’s only because I haven’t touched it for ages and the current Glade shuffled the elements quite a bit; it just adds the button to the dialog.

For now this is all sitting in trunk, I’ll do a new upstream release and Ubuntu precise upload soon.

Happy debugging!

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pitti

7 years ago, The Ubuntu 4.10 “The Warty Warthog” was announced. A huge congrats to the community, Canonical, and especially Mark for getting so far from “there” to “here”.

This brings back old memories of my first conference in Oxford in August, the great-great-grandfather to what is UDS these days. Back then, there was no company, no Launchpad, no Blueprints, no work items, no detailled plans, just a bunch of ideas, BoFs, and this was a third of the entire crowd:

Warty Hack Room

Back then we worked on the famous TRLS technology (“Totally Rad Laptop Support”) and were proud when we got the ThinkPads to suspend once. During that conference I wrote pmount to provide automatic mounting of USB sticks in a safe manner. Those were the days… :-)

But I can also safely say that there are some things that haven’t changed. Even though both the community and the company (which changed away from www.no-name-yet.com recently) grew by two magnitudes since then, we still have the same serious attitude, stern look, and formal attire as we had back then:

We are professionals, really!

We are professionals, really!

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pitti

Ich habe gerade Gestatten, Elite zu Ende gelesen (ging schnell, hab erst gestern angefangen). War im Grunde genommen nichts wirklich Neues, was man nicht irgendwie schon gewusst oder geahnt hätte. Aber die gut recherchierte und bewiesene Vehemenz, mit der sich die Oberschicht abschottet und sich selbst als eine Art neuer Adel erhält und das vielbeschworene Leistungsprinzip untergräbt war dann doch schon recht schockierend für mich.

Eine der “Elite”-Schulen die dort unter die Lupe genommen wird — Schloss Neubeuern — haben wir auf unserer Sommerradtour gesehen. Ich war schon beeindruckt von dem Haus, und damals habe ich auch gedacht “Mensch, auf so einer Schule hätte ich mich vielleicht wohlgefühlt”. Aber nach dieser Lektüre bin ich heilfroh dass es mich da nicht hinverschlagen hat.

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pitti

Hot on the heels of the PostgreSQL 9.1.0 release I am happy to announce that the final version is now packaged for Debian unstable, the current Ubuntu development version “Oneiric”, and also in my Ubuntu backports PPA for Ubuntu 10.04 LTS, 10.10, and 11.04.

Enjoy trying out all the cool new features like builtin synchronous replication or per-column collation settings for correctly handling international strings, or an even finer-grained access control for large environments. Please see the detailled explanation of the new features.

As already announced a few days ago, 9.0 is gone from Ubuntu 11.10, as it is still only a development version and not an LTS. 9.1 will be the version which the next 12.04 LTS will support, so this slightly reduces the number of major upgrades Ubuntu users will need to do. However, 9.0 will still be available in Debian unstable and backports, and the Ubuntu backports PPA for a couple of months to give DB administrators some time to migrate.

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pitti

PostgreSQL 9.1 has had its first release candidate out for some two weeks without major problem reports, so it’s time to promote this more heavily. If you use PostgreSQL, now is the time to try it out and report problems.

We always strive to minimize the number of major versions which we have to support. They not only mean more maintenance for developers, but also more upgrade cycles for the users.

9.0 has not been in any stable Debian or Ubuntu release, and 9.1 final will be released soon. So we recently updated the current Ubuntu development release for 11.10 (“oneiric”) to 9.1. In Debian, the migration from 8.4/9.0 to 9.1 is making good progress, and there is not much which is left until postgresql-9.0 can be removed.

Consequently, I also removed 9.0 from my PostgreSQL backports PPA, as there is nothing any more to backport it from. However, that mostly means that people will now set up installations with 9.1 instead of 9.0, and won’t magically make your already installed 9.0 packages go away. They will just be marked as obsolete in the postgresql-common debconf note.

If you want to build future 9.0 packages yourself, you can do this based on the current branch: bzr branch lp:~pitti/postgresql/debian-9.0, get a the new upstream tarball, name it accordingly, add a new changelog with a new upstream version number, and run bzr bd to build the package (you need to install the bzr-builddeb package for this).

Update 2011-09-09: As I got a ton of pleas to continue the 9.0 backports for a couple of months, and to keep it in Debian unstable for a while longer, I put them back now. I also updated the removal request in Debian to point out that I’m mainly interested in getting 9.0 out of testing. I don’t mind much maintaining it for a couple of more months in unstable. My dear, I had no idea that my backports PPA was that popular!

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pitti

The tool to reprocess an Apport crash report to produce a symbolic stack trace, apport-retrace, has been pretty hard to use on a developer system so far: It either installed the packages from the crash report, plus its debug symbol packages (“ddebs”) into the running system (which frequently caused problems like broken dependencies), or it required setting up a chroot and using apport-chroot with fakechroot and fakeroot.

I’m happy to announce that with Apport 1.22, which landed in Oneiric yesterday, this has now become much easier: In the default mode it just calls gdb on the report’s coredump, i. e. expects that all the necessary packages are already installed and will complain about the missing ones. But with the new --sandbox/-Smode, it will just create a temporary directory, download and unpack packages there, and run gdb with some magic options to consider that directory a “virtual root”. These options haven’t been available back when this stuff was written the first time, which is why it used to be so complicated with fakechroots, etc. Now this does not need any root privileges, chroot() calls, etc.

As it only downloads and installs the bare minimum, and does not involve any of the dpkg/apt overhead (maintainer scripts, etc.), it has also become quite a lot faster. That’s how the apport retracers were able to dig through a backlog of about a thousand bugs in just a couple of hours.

So now, if you locally want to retrace or investigate a crash, you can do

   $ apport-retrace -s -S system /var/crash/_usr_bin_gedit.1000.crash

to get the stack traces on stdout, or

   $ apport-retrace -g -S system /var/crash/_usr_bin_gedit.1000.crash

to be put into a gdb session.

If you do this regularly, it’s highly recommended to use a permanent cache dir, where apt can store its indexes and downloaded packages: Use -C ~/.cache/apport-retrace for this (or the long version --cache).

You can also use this to reprocess crashes for a different release than the one you are currently running, by creating a config directory with an appropriate apt sources.list.

The manpage has all the details. (Note that at the time of this writing, manpages.ubuntu.com still has the old version — use the local one instead.)

Enjoy, and let me know how this works for you!

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pitti

Wir sind wieder da, und diesmal sogar völlig ohne menschliche oder radtechnische Schäden! Im letzten Jahr ging unsere Radtour an der Donau entlang von Passau nach Wien, was eher gemütlich war. Diesmal hat es uns an den Inn verschlagen, wo wir die Kultur vom letzten Jahr eingetauscht haben gegen das Hochkeuchen und Runterrasen eines alpin geprägten Berg-Wegprofils.

Das war unsere erste Radtour mit “richtigen” Bergen, wo man auch schon mal 200 Höhenmeter in der Stunde hoch und wieder runter schafft. Mit unseren Tourenrädern und viel Gepäck (Zeltausruestung) mussten wir auch stellenweise schieben, aber so oder so fand ich es eine gute sportliche Herausforderung. Und der fantastische Blick ins Tal mit den Bergen drumherum entschädigt auf jeden Fall für die Mühe!

Der Inn fliesst aus dem Lej da San Murezzan

Blick hinauf nach Guarda

Blick hinauf nach Guarda

Der alpine Teil startete in St. Moritz in der Schweiz, wo der Inn aus dem See “Lej da San Murezzan” quasi entspringt (die eigentliche Quelle ist noch höher in Majola, aber da mit dem Zug/Bus hinzukommen war dann zu anstrengend). Der Inn führte uns dann über Zernez, Scuol, Pfunds (dann schon in Österreich), Landeck, Imst, Innsbruck zunächst bis Kufstein.

Dort, an der österreich-deutschen Grenze, hörten dann auch die Alpen fast schlagartig auf, und von da an ging es dann eher gemächlich fast ohne größere Steigungen weiter über Rosenheim, Altötting, Braunau, und Bad Füssing bis nach Passau, wo der Inn dann in die Donau fließt. Wir sind bis zum “bitteren Ende” gefahren zum Dreiflüsse-Eck:

Inn-Brücke in Passau

Dreiflüsse-Eck in Passau

Zwischendurch gab es auch noch ein paar Höhepunkte:

In Imst sind wir mit dem “Alpine Coaster” 3,5 km den Berg heruntergedonnert, eine Art Sommerrodelbahn im Achterbahnformat. Den wollten wir ja schon vor ein paar Wochen bei unserer Klettersteig-Tour ausprobieren, aber leider brauchte der Auf- und Abstieg viel mehr Zeit als geplant, so dass Bergbahn und Coaster schon geschlossen hatten. Auch diesmal taten Wetter und nicht fahrende Busse ihr möglichstes, uns davon abzuhalten, aber diesmal haben wir gewonnen! Hat sich auch wirklich gelohnt.

Kristall-Modell des Lenin-Mausoleums

In Wattens haben wir uns die Glitzerwelt der Swarovski-Kristallwelten angeschaut. Es war im großen und ganzen eher eine Kunst-Ausstellung, ich hatte etwas anderes erwartet, aber der riesige Kristall-Dom (kuriose Akustik da drin!) und die Kristallmodelle berühmter Gebäude waren schon faszinierend.

Auf dem Weg gab es auch noch viele andere Eindrücke, wie das sehr schöne Dorf Neubeuren, das Geburtshaus von Papst Benedikt in Marktl oder das Vogelschutzgebiet Europareservat unterer Inn. Aber die meiste Zeit haben wir dann doch mit Radeln, und nachmittags mit faulenzen und lesen verbracht, so dass es ein wirklich entspannender Urlaub wurde.

Alle Fotos der Tour

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pitti

Hot on the heels of the Announcement of the second 9.1 Beta release there are now packages for it in Debian experimental and backports for Ubuntu 10.04 LTS, 10.10. and 11.04 in my PostgreSQL backports for stable Ubuntu releases PPA.

Warning for upgrades from Beta 1: The on-disk database format changed since Beta-1. So if you already have the beta-1 packages installed, you need to pg_dumpall your 9.1 clusters (if you still need them), and pg_dropcluster all 9.1 clusters before the upgrade. I added a check to the pre-install script to make the postgresql-9.1 package fail early to upgrade if you still have existing 9.1 clusters to avoid data loss.

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pitti

Two weeks ago, PostgreSQL announced the first beta version of the new major 9.1 version, with a lot of anticipated new features like synchronous replication or better support for multilingual databases. Please see the release announcement for details.

Due to my recent moving and the Ubuntu Developer Summit it took me a bit to package them for Debian and Ubuntu, but here they are at last. I uploaded postgresql-9.1 to Debian experimental; currently they are sitting in the NEW queue, but I’m sure our restless Debian archive admins will get to it in a few days. I also provided builds for Ubuntu 10.04 LTS, 10.10. and 11.04 in my PostgreSQL backports for stable Ubuntu releases PPA.

I provided full postgresql-common integration, i. e. you can use all the usual tools like pg_createcluster, pg_upgradecluster etc. to install 9.1 side by side with your 8.4/9.0 instances, attempt an upgrade of your existing instances to 9.1 without endangering the running clusters, etc. Fortunately this time there were no deprecated configuration options, so pg_upgradecluster does not actually have to touch your postgresql.conf for the 9.0 ?9.1 upgrade.

They pass upstream’s and postgresql-common’s integration test suite, so should be reasonably working. But please let me know about everything that doesn’t, so that we can get them in perfect shape in time for the final release.

I anticipate that 9.1 will be the default (and only supported) version in the next Debian release (wheezy), and will most likely be the one shipped in the next Ubuntu LTS (in 12.04). It might be that the next Ubuntu release 11.10 will still ship with 9.0, but that pretty much depends on how many extensions get ported to 9.1 by feature freeze.

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pitti

Update at 13:06 UTC: Corrected NetworkManager description, thanks Mathieu for pointing out.

A few months ago, Matt Zimmerman kicked offa new tradition of a quarterly review of the most popular Ubuntu Brainstorm ideas. He did the December review, now it was my turn to coordinate the March review.

7zip desktop support (#26504)

The 7zip compression format becomes increasingly more popular these days; Ubuntu releases up to 10.10 did not support it on the desktop support as well as older formats like zip or bzip2.

Ubuntu developer Sebastien Bacher responds:

The 7z format has in fact been supported by file-roller for quite some time but it does require the installation of the command lines utilities to work. The issue is pretty much addressed in Ubuntu 11.04 (Natty) though since file-roller [...] will ask you if you want to install “p7zip” when you try open an archive using that format.

The other part of the brainstorm request is to also add support for it to gvfs, i. e. that you can browse a 7zip archive as a virtual storage device.This can’t be supported, as the library which is used for this (libarchive) only supports streamable format for efficiency. 7zip is not streamable, and thus would provide a very poor performance.

Empty directories in the Nautilus file manager (#26335)

In tree view mode, nautilus currently displays an expander symbol even if a directory is empty. This looks slightly confusing and makes it harder to see which directories actually have content.

This is indeed a long-standing known problem (the upstream bug is almost ten years old!). Rodrigo Moya, one of the GNOME maintainers in the Ubuntu desktop team, explains why fixing this is actually a lot harder than it might seem initially: Checking each folder to see if it’s got children or not might be time and CPU consuming when displaying lots of subfolders; it gets worse if you are browsing a directory on a remote or slow virtual file system like gphoto cameras or compressed tarballs.

One possible improvement would be to do the test asynchronously and display/hide the expander arrow as the subfolders are checked, and possibly restrict this to local file systems with a maximum number of directory entries. This would create an inconsistency, though.

So unfortunately it is not very realistic to see this being addressed soon.

Login screen (gdm) improvements (#26482)

This item suggests adding features to gdm which make it more useful, such as adding a clock, widgets, or a guest session without requiring an already existing running user session.

Ubuntu and GNOME developer Robert Ancell has a lot of experience with both gdm as well as his own LightDM project.

He points out that in GNOME 3 a clock was added to the login screen and looks similar to the proposed design. So we will get that in Ubuntu 11.10. Other changes to gdm should be discussed and proposed in the upstream bug tracker.

For 11.10 there is an existing proposal to use LightDM by default. LightDM offers a a lot more and easier possibilities for customization and theming, so any contributions for writing widgets or other improvements will be welcome.

Easy side-by-side window arrangement (#26152)

With nowaday’s modern big screens it often is too wasteful or even impractical to run applications fullscreen. A common case is to arrange two applications (such as a web browser and a document editor) side by side. This hasn’t had any particular support up to Ubuntu 10.10, aside from moving and resizing windows manually to fit.

John Lea of the Canonical Design Team explains how the main use case has been implemented in Ubuntu 11.04:

Windows can be opened into semi-maximised state where they occupy 50% of the screen width simply by dragging the window to the left or right border of the screen. A preview shadow informs the user that if they drop the window in this location the window will be resized. This interaction provides a simple, clean solution to the problem without introducing any additional window chrome.

Note that the remaining part of the request, resizing two adjacent windows at the same time, is not currently provided. It is quite a complex interaction which can also trigger false positives, and probably also requires some deeper design studies to get the user experience and definition of “adjacent” right. There are currently no plans to implement this.

man usability (#25975)

First-time users of the man utility often wonder how to quit the program again after they are done reading. Neither the manpage itself nor –help explain that, or other keys for navigation.

Colin Watson is one of the man-db upstream developers. He responds:

I’ve made a change upstream for man-db 2.6.0 which will address this, by adding “(press h for help or q to quit)” to the default prompt string which is displayed on the bottom line of the screen when reading manual pages. I think this is a reasonable balance between providing guidance and taking up too much screen space, and people who get fed up of seeing it can always follow the documentation in man(1) for customising the prompt.

[...] It will definitely be in Ubuntu 11.10.

Naming of Ethernet connections in the UI (#27250)

When connecting to a wired network, it automatically gets assigned a name like “Auto eth0″. Many people will not know what this is, or even if they do, distinguishing between one or another is difficult.

Our NetworkManager maintainer Mathieu Trudel-Lapierre adopted this problem, and wrote a detailled blog entry about how connection naming will be done in Ubuntu 11.10. In particular, network-manager will make the meaning of the default profiles clearer, and notifications will contain “Wired network” in addition to “eth0″. We still need to keep the actual interface name for more experienced users who want to customize their network configuration.

For the case of telling apart multiple ethernet adapters, Ubuntu 11.04 already layed the foundation for integrating biosdevname, which will provide more meaningful names to Ethernet ports than just enumerating them in an arbitrary order, provided that the BIOS provides names for these. It is not enabled by default yet, but might be in 11.10.

Save dialogs should have the three most recently used folders (#26471)

When saving files you often choose the same couple of folders to store your data. Sadly, the drop down menu for the save-as-dialog box only shows the last folder where you have saved a file. Another common use case is to save a document in e. g. Firefox somewhere, and wanting to open it in another application again.

The desktop world is moving towards better tracking of what the user did most recently, so we asked the Zeitgeist developers about the feasibility of this. Manish Sinha discussed the idea within the project and also with the GTK developers, and summarized the possible options in an email to the technical board list.

We don’t currently know about any developer who wants to work on this. GTK developer Federico Mena Quintero said that it is not too difficult to do, and that he would be happy to guide someone who wants to pick this up. So if this interests you, please give him a ping.

Configure auto-mounting of internal drives (#26946)

Ubuntu (and GNOME in general) does not automount internal hard drive partitions in general, as this might cause unwanted data disruption on e. g. Windows system partitions, and also has a performance impact. However, in some use cases it would actually be practical to do so for selected partitions.

David Zeuten and Martin Pitt, the current udisks upstream maintainers, discussed options how this should be integrated and found an agreement (see the response in brainstorm for details). In short, the gnome-disk-utility program will grow some options which allow you to configure individual partitions similar to this:


Automatically mount this drive:
( ) Never
(X) When I log in
( ) On computer startup

(note that this is in no way a finished design or even user fiendly strings).

The current timeline for this is to implement this for GNOME 3.4, which would be in time for Ubuntu 12.04.

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pitti

As a followup action to my recent Talk about PyGI I now re-used my notes to provide some real wiki documentation.

It would be great if you could add package name info for Fedora/SUSE/etc., and perhaps add more example links for porting different kinds of software! Please also let me know if you have suggestions how to improve the structure of the page.

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