Search Results: "ron"

13 September 2011

Christian Perrier: 10 years being Debian Developer - part 4: NM process

So, this story begins in January 2001, when I applied in the Debian New Maintainer Process. I wanted to maintain Geneweb, which I was using to publish my genealogy research results. And I wanted to keep it up-to-date while upstream was doing a quite fast development. Moreover, I quickly noticed that Geneweb had big trouble in respecting the way data is organized on a Debian system, and respect the FHS. How to have weveral users able to publish their data on the same server without compromizing the overall system security, etc. Upstream development didn't really care about that. Daniel de Rauglaudre is an excellent genealogist and developer but he was not interested in making Geneweb clean "the Debian way". For instance, at that time, it wasn't easy to setup a server, where genealogy databases could be published without having to manually launch a daemon in user mode at each reboot. Arranging this was indeed my first contribution. I contributed a few patches to make it easier to turn Geneweb into something FHS-compliant...and I developed init scripts and an organization allowing one to have shared databases after system reboots. That was rapidly a great introduction to Debian maintainer scripts and even security-related challenges. And all this....because I needed it. Basically, in 2001, the geneweb package adopted the organization it still has in Debian and Ubuntu, 10 years later: While doing so, I was going through the New Maintainer Process. The Debian developer who had signed my key was Sam Tardieu, of of those longstanding "Freenix" dudes I was sometimes hanging around. I don't remember who did write my advocacy. Michael Mattice was my first Application Manager. Interestingly, here are the three first questions he asked my as part of the Policy and Procedures check : Mike actually asked the questions on February 17th and I probably answered immediately. Unfortunately it seems that I lost my answers. Maybe they are in some archive somewhere. Would be interesting to see how I ended giving an answer about the TeX exception.:-) Immediately, Mike moved to the Tasks and Skills step and checked my geneweb and lifelines packages (I already prepared a package for that other genealogy software). From my records, he found a few lintian warnings, which I probably made my best to fix, then later on, on March 12th, he answered me that thigns were OK and he was marking the T&S step as passed...handing things over to the NM database, asking me what username I wanted on debian.org (obviously, you know what I answered to this!). Then nothing happened..:-) I was not that impatient, but finally, around June 27th, I politely mailed NM Frontdesk (I guess) to get news...and I got a very quick answer by Martin Michlmayr. Martin was indeed worried about the situation (he told me I was on his radar....fun as, many years later, as many DDs, Martin probably went on mine because of pending localization work..:-)) Finally, Martin decided he was not entirely happy with the (maybe too short) processing for P&P and proposed me (very politely, you know how Martin is!) to do it again. So, some more questions...:-) Here, I have the answers. Really fun ro read. Hang on, pure bubulle style, very verbose! What a bunch of questions..:-). Reading my answers ten years after, I see that some answers are somehow naive but, after all, they're not so bad. I really remember spending hours in writing them (my English was somehow more shaky at that time) The last question was: "Please tell me about about yourself and what you intend to do for Debian". Here, Martin opened a big can of worms..:-) So, you'll learn about this in the next episode..:-)

Raphaël Hertzog: Understand dpkg and don t get stuck with a maintainer script failure

Continuing my series of articles on dpkg s errors, this time I ll cover a pretty common one which has several variations:
Setting up acpid (1:2.0.12-1) ...
rm: cannot remove  /etc/rc1.d/K20acpid': No such file or directory
dpkg: error processing acpid (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 acpid
Even if dpkg is failing and outputting the error message, the real problem is not in dpkg but in the installed package (acpid in the example above). As we already learned, a package contains not only files but also maintainer scripts that are executed at various points of the installation process (see some useful graphics to understand how they are called, thanks to Margarita Manterola).

Maintainer scripts in a package upgrade

In the introductory example it was acpid s post-installation script that failed, and dpkg is only forwarding that failure back to the caller. The maintainer scripts are stored in /var/lib/dpkg/info/. You can thus inspect them and even modify them if you hit a bug and want to work around it (do this only if you understand what you do!). One common modification is to add set -x at the start of the script and to retry the failing operation. That way you can see what s executed exactly. Here s what the output could look like after the addition of set -x to /var/lib/dpkg/info/acpid.postinst:
$ sudo dpkg --configure acpid
Setting up acpid (1:2.0.12-1) ...
+ dpkg --compare-versions 1:2.0.11-1 lt-nl 1.0.10-3
+ dpkg --compare-versions 1:2.0.11-1 lt-nl 1.0.6-16
+ dpkg --compare-versions 1:2.0.11-1 lt 1.0.6-6
+ rm /etc/rc1.d/K20acpid
rm: cannot remove  /etc/rc1.d/K20acpid': No such file or directory
dpkg: error processing acpid (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 acpid
This output helps you locate the command that is actually failing. Here s it s relatively easy since we have an error message from rm . And the fix is trivial too, we replace rm with rm -f so that it doesn t fail when the file doesn t exist (this is a fake bug I made up for this article I just added a failing rm call but it s inspired by real bugs I experienced). Maintainer scripts are supposed to be idempotent: we should be able to execute them several times in a row without bad consequences. It happens from time to time that the maintainer gets this wrong on the first try it works, so he uploads his package and we discover the problem only later once someone ended up executing the same code twice for some reason.

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Martin Pitt: PostgreSQL 9.1 final packages available for Debian/Ubuntu

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.

12 September 2011

Antonio Terceiro: Laptop fun, or "WTF, HP?"

A couple of weeks ago my old laptop decided to rest forever, and I was forced to impose some economic pressure onto the consumption of the planet resources by acquiring a new one. Fortunately this happened while I am still here in Canada, where it is reasonably cheaper to get a decent laptop than it is in Brazil. Although I did not have the budget I wanted for buying a really kick ass laptop, I was able to buy a decent one, an HP Pavilion G6 1B74CA. I went on 4 different shops with a USB stick loaded with Debian Live to check whether all the hardware would work ok. I always asked one of the salesman before rebooting the laptops, but it was funny to see the reactions of the different employees who came by to check what I was doing: some of them barely noticed that GNOME was not Windows XYZ, and and some asked whether I was hacking the laptops. Unfortunately, I wasn t able to find a single laptop in which the wireless worked out of the box with the Squeeze kernel, which sucks. I searched over the internet a lot, and it seems that even the vendors recommended by the FSF do not provide laptops with wireless cards that work without non-free blobs. Other issue I had was with the Intel graphics. After the kernel enables the modesetting, the backlight goes to the minimum and it looks like you have no video. There are a couple of workarounds in the internet, and the one in which you add acpi_osi=Linux acpi_backlight=vendor to the kernel parameters makes the laptop turn on by itself in the morning. This is probably caused by broken ACPI handling in the BIOS, who almost always is written by people on crack. The other issues I had were related to the keyboard. First, the BIOS came by default with Access keys mode enabled, which means that by default pressing F2-F12 actually activated the multimedia keys instead of the real function keys. It was disapointing to hit F12 and have my wireless turned off. After disabling this in the BIOS setup, it was OK. Well, not quite: for some reason, Fn+F4 did not generate the expected keycodes. After some research on the internet, I found a interesting Ubuntu bug . It seems that the latest and greatest version of Windows starts its video setup application via the Meta+P shortcut ( Meta is the actual name of what Windows people call the Windows key ). Guess what the morons writing the HP BIOS did yes, they made the keys Fn+F4 (where F4 has video setup as its multimedia key ) generate the keycodes for Meta+P! It would be a lot easier for everyone in the world if the people at Microsoft just make their stuff listen to both Meta+P and the video setup keycode, which is generated by every laptop out there, to activate the Windows screen setup thing. This way the very smart dudes writing BIOS at HP wouldn t need to make Fn+F4 generate the keycodes for Meta+P and break every single desktop that is not procuced at Redmond.

John Goerzen: Mexico Part 3: Shopping

The third in my serious about my family s recent visit to Mexico see also part 1 and part 2. Shopping in Mexico was probably the thing I was least prepared for. I probably had the biggest wins of the trip shopping, and also the biggest fails (though they weren t all that significant). It seems to me that shopping is all about serendipity. You almost have to be good at impulse buying. I normally try hard to resist impulse purchases, preferring to research and compare carefully before making a decision. That attitude didn t serve me well in Mexico, and when I was able to overcome it, I got some great purchases. Around here, some of the best places to shop are the ones that have been in business for decades. Anderson Office Supply in Newton, KS, for instance, has been around for over 100 years, and has in stock, even everything from a ribbon for my slightly obscure 1940s typewriter to local history books. Moler s Camera in Wichita often meets or beats the online stores prices, and has better service. But in Mexico the best places seemed to be packed into a large crowded shopping area, or a dusty stand along a road, or a guy selling stuff on a plaza somewhere. Here is Guadalajara s market (San Juan de Dios): It s an incredible open-air market. We spent quite some time there, even ate lunch, and yet I m sure we saw only a small fraction of what they had. It was a cramped place, with small booths and tiny aisles, but all sorts of interesting things. Although I did appreciate walking quickly past the raw pork and fish corner. Terah bought some genuine extract of vanilla there, at a good price. Some of the street vendors were selling what I think were butterfly toys they had some sort of launcher that would launch them in the air, and they d flutter and float down to the ground. We saw them mainly in Guadalajara Centro on our first day, and I (unwisely, it turns out) thought, Hmm, a plastic toy our boys would love it, but I don t want to buy it on our first day. Besides, I m sure we ll see them all over or online. Wrong on both counts. So there s one of my fails. My greatest win came on the road back from Guachimontones (an ancient pyramid site). Every so often along that country road, there would be a vendor with a table selling something or other. I saw some paintings out my window, thought neat , but and here you can see how terrible an impulse buyer I am didn t actually put together that we should turn around and look at them until 10 minutes later after a bathroom stop for Jacob. We went back, and I picked out a beautiful painting on canvas of those pyramids at sunset. And the charge: 200 pesos (about $17 USD). Incredible and incredibly cheap, and there is a great place on my wall for it. The vendor was also the artist. I am kicking myself for only buying one. (No photo yet as it was too big to practically transport by plane.) Another memorable purchase was this one: This was another roadside find. We were driving through Ajijic, and I noted a rug vendor along the side of the road. I had walked past a rug vendor in the Guadalajara market, so I was keeping my eye out. I made a note to stop there on our way back out of Ajijic. So we did. This is a rug made in the Zapotec tradition, all hand-made, with natural dyes and wool. It was 550 pesos (about $46 USD), which I considered to also be a pretty good deal for what it was. I have no idea how many hours went into creating it, but I m sure it was many. My luck in shops wasn t so good. We visited Tlaquepaque, which had lots of shops selling beautiful things. But the prices there were higher than I d pay for similar things back home. Tonala s shops were too inconveniently located to be practical with what were then tired boys, so we didn t go in there. I m not used to shopping without planning, and perhaps am not very good at it. On the other hand, I really enjoyed making those two purchases, and only regret not buying another 200-peso painting! Maybe next time I m in Mexico, I ll even buy something on the first day there. Terah will be so proud..

Kees Cook: 5 years with Canonical

This month, I will have been with Canonical for 5 years. It s been fantastic, but I ve decided to move on. Next week, I m going to start working for Google, helping out with ChromeOS, which I m pretty excited about. I m sad to be leaving Canonical, but I comfort myself by knowing that I m not leaving Ubuntu or any other projects I m involved in. I believe in Ubuntu, I use it everywhere, and I m friends with so many of its people. And I m still core-dev, so I ll continue to break^Wsecure things as much as I can in Ubuntu, and continue working on getting similar stuff into Debian. :) For nostalgic purposes, I dug up my first security update (sponsored by pitti), and my first Ubuntu Security Notice. I m proud of Ubuntu s strong security record and how far the security feature list has come. The Ubuntu Security Team is an awesome group of people, and I m honored to have worked with them. I m looking forward to the new adventures, but I will miss the previous ones.

2011, Kees Cook. This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 License.
Creative Commons License

Dirk Eddelbuettel: RQuantLib 0.3.8

A bug-fix release RQuantLib 0.3.8 is now on CRAN and in Debian. RQuantLib combines (some of) the quantitative analytics of QuantLib with the R statistical computing environment and language. Thanks to Helmut Heiming who noticed a side-effec t from the DiscountCurve functions: the Quantlib-global variable determining the evaluation date was overriden; this could affect subsequent curve-related pricers. This is now fixed, and we added a new function setEvaluationDate to set this date from R too. We added this call in some of the examples in the manual pages. Otherwise two very minor build system tweaks were added, but no other changes were made Thanks to CRANberries, there is also a diff to the previous release 0.3.7. Full changelog details, examples and more details about this package are at my RQuantLib page.

John Goerzen: Mexico Part 2: Lodging & Family

As I wrote in part 1, my family and I were in Mexico recently. Today I ll write about the places we stayed. We spent most of the time in a room we rented in a private home in Guadalajara. My friend Jonathan had found it for us, and it was not too far from his home. The owner was a grandmother, and across the courtyard was more family, including a granddaughter close in age to our boys. They enjoyed playing together. It was really a perfect arrangement for us. There s no better way to be a part of local life when traveling than to stay in someone s house. Here s our bedroom: Notice the glass slats in the window it s a nifty, though not airtight, alternative to our regular windows. More on that later. More of the inside: We had a bit of a language barrier while in Mexico, though never anything significant. My Spanish vocabulary started with almost nothing and I reached maybe a few dozen words by the time we left. Terah knew some Spanish from high school and college, and my friend was fluent. Our hostess also knew a little English. But we all communicated well enough. Terah or Jonathan would help translate when needed. As I d seen before, the children would say things to each other, but never seemed to be bothered that their playmates didn t understand what was being said. They just had a great time anyhow. On Sunday afternoon, when we came back from our activities, there was a buzz of activity. Children everywhere outside, running and playing. Adults too, chatting. We didn t know exactly what was happening, but sent Jacob and Oliver out to play anyhow (which they were eager to do). The yard was enclosed by a wall, so children could pretty much run around without lots of supervision. Eventually they were invited to have some birthday cake (ah ha!) it was one of the children s birthday. Jacob and Oliver actually were served the first two pieces of cake (as the amigos ). Everyone seemed so friendly, warm, and welcoming. Each morning started with breakfast at the house, followed by a scene like this: That s Jacob and Oliver, looking to see if Jonathan had arrived for the day yet. I often noticed in Mexico that I was unsure if I was inside or outside. Here in Kansas, we can have a string of summer days that each exceed 110F (44C) or a few weeks in winter that never get above 15F (-9C), even in daytime. And then we have some pleasant days like right now, too or rain blowing sideways at 60MPH. In general, we spend a lot of effort keeping the outside, well, out. It is quite clear that this isn t a problem in the Guadalajara area. Some restaurants could have been described as buildings with large, open windows so you feel a lot of breeze while inside. Or perhaps as a simple shade roof with a few supports on the edges, so you re never really inside at all (sort of like going under a small shade tent outdoors). To the extent that windows could close, many of them couldn t be made airtight. It was clear that in that area, people spend more energy finding ways to invite the outdoors in rather than to keep it out, thanks to the year-round moderate climate. Perhaps the best example of this surprised me one evening. We were arriving in Guanajuato, an old silver mining town in the mountains, and were going to spend the night at Hotel Socav n, which had been recommended to us by a local friend of Jonathan s. From the street, the hotel looked tiny. But walk in, and you get in this old-looking (and feeling) entry tunnel: That s the front desk, apparently cut out of it there on the right. We asked to see some of the rooms before buying apparently a normal request around there. The innkeeper agreed, and gave us keys and directions to find them on the third floor. It included going up 2 flights of stairs, passing through a courtyard, and going up another flight. It was after dark, and the hotel was dimly lit something I was fine with. I thought we were stepping out into a beautiful atrium with some potted plants in the center of the building something fairly common in some nicer hotels. Until I felt rain on my head. Then I realized that the courtyard, which began two floors up from the street, was open to the sky. Beautiful! Here was the view from out room door: And down the hall : After getting home, a Google happened to turn up some reviews of this hotel. I was so annoyed at what some people wrote! One person gave them only 3 stars because they didn t have air conditioning, had poor water pressure, and lots of steps . Someone else complained of the dark entry tunnel something I couldn t help but smiling about the moment I entered. My review, which should hopefully get posted soon, is certainly different. I gave them 5 stars, because if I wanted a Super 8 with generic fluorescent lighting and the same layout as thousands of other hotels, I would have gone to Nebraska instead of Mexico. Most homes and local hotels in the region don t have air conditioning because they don t need it, and that s just how water pressure is in Mexico (due to needing to pump it from municipal supplies to private storage tanks overhead). And who doesn t appreciate entering a hotel through a brick tunnel? Ah, sigh This should give you some idea of the kind of travel we like: part of the point of traveling is enjoying the differences from home, and I think it is a huge mistake to be annoyed at everything that is different. Enjoy the differences! Finally, here s a photo of the staircase in the home we stayed in, which I thought was fascinating:

9 September 2011

Mike Hommey: Initial VMFS 5 support

Today I added an initial VMFS 5 support to vmfs-tools. For the most part, VMFS 5 is VMFS 3, so these should just work as before, and adds new features; but this initial support is very limited: On related news, while the git repository here is kept alive, I also pushed it to github. The main reason I did so is the Issue tracker. Update: It turns out the small file support makes the vmfs-tools crash when accessing files bigger than 256GB, because the assumption made when reverse engineering was wrong and clashes with how files bigger than 256GB are implemented. It also turns out large single extent volumes may be working already because it looks like it was only about tuning an existing value, like smaller sub-block and increased file count. Update 2: Latest master now supports small files without crashing with files bigger than 256GB.

Russell Coker: Modern Laptops Suck

One of the reasons why I m moving from a laptop to a cloud lifestyle [1] is that laptops suck nowadays. Engineering Trade-offs Laptops have always had disadvantages when compared to desktop systems. The screen has to be smaller, the keyboard is inconveniently small on the smaller laptops and netbooks, you don t get PCI slots (CardBus isn t nearly as good), you usually can t have multiple hard drives and expansion options for other things are limited. Also due to the difficulty in designing a computer that uses a small volume it s very difficult to repair a laptop and there are no realistic options for upgrading the motherboard to use a faster CPU etc. This is OK, it s engineering trade-offs that we have to deal with. CPU Speed Modern laptops however have some bad design choices. Firstly they appear to be trying to compete with desktop systems for CPU speed. This was reasonable when desktop systems had 200MHz CPUs which dissipated about 15W (see the Wikipedia page about CPU power dissipation) but now that desktop CPUs are dissipating 65W at the low end and more than 100W at the high end it s really not practical to try and compete. My Thinkpad T61 has a T7500 CPU that can dissipate 35W, getting that much heat out of a laptop case is a significant engineering challenge no matter how you do it. It s a pity that no-one seems to be making laptops with large screens that have a low-power CPU. Sure it takes a moderate amount of CPU power to use a large display for games or playing video, but if you want to use a laptop for work purposes then not much CPU power is required. For tasks which take a lot of CPU power you can offload it to the cloud, I can ssh to a server to do compiles, and one of my clients is setting up an Adobe After Effects render farm [2] (in the broadest sense of the word Cloud can include a server accessed by ssh and a few servers on the LAN running After Effects). Thin Laptops The next problem is laptops being thin, it is really convenient to have a thin laptop, but the thinner it is the smaller the fans have to be and the faster the cooling air has to travel through small heat sinks. At the best of times this results in more noise from the cooling fan (which really isn t so bad). But it also increases the rate at which dust builds up inside the case and insulates the heat sink. When a laptop is thin and light for convenience and also wide to have a large display it just can t be that strong, so laptops tend to bend. If I put an Australian 10c piece (the size of a US Quarter) under one of the feet of my Thinkpad T61 the other three feet touch the desk! Presumably the laptop would bend in every way imaginable if you were to put it on your lap which of course you can t do because there are cooling vents in the bottom so it can give you a hot lap and an overheated laptop. My first Thinkpad was 61mm high according to the IBM spec sheet. I measured my latest one at 34mm. As 61mm wasn t too bad I think I could survive now with a laptop that was 45mm high and had more strength and less cooling problems. My Thinkpad T61 currently has some serious cooling problems, I suspect that something is broken inside. As it s out of warranty I took it apart but couldn t find anything wrong, so I guess I ll have to pay to get it repaired. This will be the third time I ve had a Thinkpad repaired because of cooling problems, but the first time one has been out of warranty. I blame the engineering trade-offs required to make them thin. Portable Desktop/Server systems If you want a small portable computer that delivers great performance then a Mac Mini seems to be a good option [3]. The people who use a laptop at their desk at work and their desk at home would probably be better served by a Mac Mini. The Mac Mini can be purchased with SSD storage to reduce the risk of data loss due to being dropped. Admittedly the Mac Mini needs to be plugged in before it can be used, but if you had a USB Ethernet device and a USB hub then only three cables would be required, power, USB, and video one more cable than the typical office laptop use with Ethernet and power. Some modern laptop/netbook systems (such as the Thinkpad T61 and the EeePC 701) seem to be designed to use the keyboard as part of the cooling system. If you run it with the lid closed then it becomes significantly hotter. This makes laptops unsuitable for use as a portable server. Probably one exception to this is the Apple laptops which have a rubbery keyboard that doesn t allow air flow of course anyone who likes the feel of a real keyboard won t buy an Apple laptop for that reason (but a keyboard that has one really hot section above the CPU doesn t feel great either). In the past I ve used laptops as servers once they become unsuitable for their primary use, probably in future I won t be able to do that. ARM Laptops There are some laptops and tablets with ARM CPUs that should dissipate little heat. But I m not aware of any such devices that I consider to be practical Linux laptops. I ve done some work with iPaQ s running Familiar in the past, it was a nice system but it was a niche market and everything was different from every other system I ve ever used. That made all the work take longer. What would be ideal is an ARM based laptop (not netbook a big screen is good) that boots from a regular CF or SD card (so the main storage can be installed in another machine to fix any boot failures) and which is supported by a major Linux distribution. Does anyone know of any work towards such a goal?

Raphaël Hertzog: People behind Debian: Enrico Zini, member of the New Maintainer Frontdesk

Enrico ZiniEven though Enrico is not smiling on this picture, he s one of the friendliest Debian person that I know. I always enjoy his presentations because he can t refrain from inserting jokes or other funny tricks. :-) That said he s serious too, there s lots of good stuff that he has developed over the years (starting with Debtags) and he has put a lot of effort in reforming the New Maintainer process. Read on to learn more about his various projects. Raphael: Who are you? Enrico: Hi, I m Enrico Zini, a DD from Italy. I m 35 and I work as a freelance Free Software developer. One of my historical roles in Debian is taking care of Debtags, but that is not all I do: my paid work led me to write and maintain some weather forecast related software in Debian, and recently I gained a Front Desk hat, and then a DAM hat. Raphael: How did you start contributing to Debian? Enrico: It was 2001, I was at uni, I was using Debian. At some point I wanted to learn packaging so I read through the whole Policy from top to bottom. Then I thought: why package only for myself? . There were many DDs at my uni, and it only seemed natural to me to join Debian as well. Evidently this was also natural for Zack [Note from editor: Stefano Zacchiroli], who had become DD 6 months earlier and didn t hesitate to advocate me. I found the Policy and the Developer s Reference to be very interesting things to read, and I welcomed my AM s questions as an excuse to learn more. I completely understand those people who have fun trying to answer all the questions in the NM templates while they wait for an AM. With my super DAM powers I can see that my AM report was submitted on October 16, 2001 by my AM Martin Michlmayr, and that James Troup created my account 9 days later, on October 25. Raphael: You have a special interest in the New Maintainer (NM) Process since you are a Debian Account Manager (DAM) and a member of the NM Frontdesk. Thanks to your work the process is much less academic/bureaucratic than it used to be. Can you remember us the main changes? Enrico: One of the first things I noticed when I become a Front Desk member is that there was a tendency to advocate people too early, thinking by the time they ll get an AM, they ll know enough . Unfortunately, this didn t always work, and once the real NM process started it would turn into a very long and demotivating experience both for the applicant and for the AM. So we tried raising the bar on advocacies, and that seems to have helped a lot. If people join NM when they are ready, it means that NM is quick and painless both for them and their AMs, who are therefore able to process more applicants. We also did a rather radical cleanup of the NM templates , which are a repository of questions that Application Managers can ask to their applicants. We realized that AMs were just sending the whole templates to their applicants, so we moved all non-essential questions to separate files, to drastically reduce the amounts of questions that are asked by default. Other improvements in the NM process came from other parts of Debian: nowadays there are lots of ways to learn and gradually gain experience and reputation inside the project before joining NM, which means that we get many candidates who we can process quickly. For example, packages can now be uploaded via sponsors, and the Mentors project helps new contributors to find sponsors and get their first packages reviewed. Then one can now become Debian Maintainer and take full responsibility of their own packages, gaining experience and reputation. The idea of working in teams also helped: big teams like the Perl, Python, KDE, Ocaml, Haskell teams (and many more) are excellent entry points for people who have something to package. But Debian is not just for packagers, and one could join teams like the Website team, the Press and Publicity team, the Events and Merchandise team or their local translation team. Becoming DDs the non-uploading way is not just for non-technical people: one could enjoy programming but not packaging. An interesting way to get involved in that way is to help writing or maintaining some of the many Debian services. Note that I m not suggesting this as a way to learn how to program, but as a way to get involved in Debian by writing code. Finally, we started to appreciate the importance of having people activities in Debian explicitly visible, which means that the more obviously good work one has done in Debian, the less questions we need to ask. Jan Dittberner s DDPortfolio is an excellent resource for AMs and Front Desk, and I m maintaining a service called minechangelogs that for people who have done lots of work in Debian is able to fully replace the Tasks&Skills parts of the NM process. Raphael: What are your plans for Debian Wheezy? Enrico: For Wheezy I hope to be able to streamline and simplify Debtags a bit more. At Debconf11 I had a conversation with FTP-masters on how to make some tags more official, and I now have to work a bit more on that. I d also like to considerably downsize the codebase behind the debtags package, now that its job is quite clear and I don t need to experiment with fancy features the way I did in the past. I have to say that I enjoy programming more than I enjoy packaging, so most of my plans in Debian are not tied to releases. For example, I d like to finish and deploy the new NM website codebase soon: it would mean to have a codebase that s much easier to maintain, and in which it s much easier to implement new features. I d also like to design a way to allow maintainers to review the tag submission to their own packages instead of having to wait for me or David Paleino to do a regular review of all the submissions. Finally, I d like to promote the usage of apt-xapian-index in more cutting-edge packaging applications. And to design a way to maintain up to date popcon information in one s local index. And improve and promote those services that I maintain, and I tend to often have ideas for new ones. Raphael: If you could spend all your time on Debian, what would you work on? Enrico: If I could spend all my time on Debian, I would do a lot of software development: I love doing software development, but most of my development energy is spent on my paid work. I guess I would start my all your time in Debian by taking better care of the things that I m already doing, and by promoting them better so that I wouldn t end up being the only person maintaining them. After that, however, I reckon that I do have a tendency of noticing new, interesting problems in need(?) of a solution, and I guess I would end up wildly experimenting new ideas in Debian much like a victorian mad scientist. Which reminds me that I most definitely need minions! Where can I find minions? Raphael: You re the author of the Debian Community Guidelines. I have always felt that this document should be more broadly advertised. For example by integrating it in the Developer s Reference. What do you think? Enrico: The DCG was really a collection of tips to improve one s online communication, based on ideas and feedback that I collected from pestering many experienced and well-respected people for some time. Like every repository of common sense, I think it should be widely promoted but never ever turned into law. It wouldn t be a bad idea to mention it in the Developer s Reference, or to package it as a separate file in the developers-reference package. The reasons I haven t actively been pushing for that to happen are two: there isn t much in the DCG that is specific to Debian, and I don t have the resources to do a proper job maintaining it. It d be great if somebody could take over its maintenance and make it become some proper, widespread, easy-to-quote online reference document, like one of those HOWTOs that all serious people have read at some point in their lives. Raphael: What s the biggest problem of Debian? Enrico: It s sometimes hard to get feedback or help if you work on something unusual. That is partly to be expected, and partly probably due to me not having yet learnt how to get people involved in what I do. Raphael: What motivates you to continue to contribute year after year? Enrico: Debian keeps evolving, so there is always something to learn. And Debian is real, so everything I do is constantly measured against reality. What more intellectual stimulation could one possibly want? Raphael: Is there someone in Debian that you admire for their contributions? Enrico: I don t think I could reasonably list everyone I admire in Debian: pretty much in every corner of the project there is someone, sometimes not very well known, who is putting a lot of Quality in what they do. Someone who decided that X should work well in Debian or that Debian should work well for Y or that Z is something Debian people can rely on and makes sure that it is so. Those are the people who make sure Debian is and will be not just a hobby, but a base upon which I can rely for my personal and working life.
Thank you to Enrico for the time spent answering my questions. I hope you enjoyed reading his answers as I did.

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8 September 2011

Sylvain Beucler: Scientific OpenGL

plot Guus started a new section in the OpenGL wikibook about scientific uses! In a first tutorial, he showcases how to interactively plot a simple mathematic function:
http://en.wikibooks.org/wiki/OpenGL_Programming#The_scientific_arc
suzanne The lighting front is also progressing with a new tutorial on ambient and specular lights:
http://en.wikibooks.org/wiki/GLSL_Programming/GLUT/Specular_Highlights
Enjoy!

Dirk Eddelbuettel: Faster (recursive) function calls: Another quick Rcpp case study

There was another question recently on StackOverflow that I had meant to discuss in a follow-up post here. User deltanovember asked about slow recursive functions and used the very classic Fibonacci number as an example. To recap, Fibonacci number are defined with two initial values F(0) = 0 and F(1) = 1; thereafter the Fibonacci number F(n) is defined as the sum of the two preceding numbers: F(n) = F(n-2) + F(n-1). This leads to very straightforward implementations using recursion:
## R implementation of recursive Fibonacci sequence
fibR <- function(n)  
    if (n == 0) return(0)
    if (n == 1) return(1)
    return (fibR(n - 1) + fibR(n - 2))
 
Unfortunately, this elegant implementation which remain close to the abtract formulation of the recurrence algorithm performs very poorly in R as there is noticeable overhead in function calls which becomes dominant in a recursion. This lead to the original question on StackOverflow, and the accepted answer uses a trick presented by Pat Burns in his lovely R Inferno: rewrite the solution using a computer science trick called memoization:
fibonacci <- local( 
    memo <- c(1, 1, rep(NA, 100))
    f <- function(x)  
        if(x == 0) return(0)
        if(x < 0) return(NA)
        if(x > length(memo))
        stop("'x' too big for implementation")
        if(!is.na(memo[x])) return(memo[x])
        ans <- f(x-2) + f(x-1)
        memo[x] <<- ans
        ans
     
 )
That is a fair answer, and even more was suggested with a link to a terrific analysis calling the Fibonacci recurrence the worst algorithm in the world. That is also fair, but all the basic research into better algorithms exploiting some structure of the problem to advance performance (and of course understanding) is overlooking one crucial part: algorithm analysis is essentially independent of the language. So whatever improvements we obtain by thinking really hard about a problem are then available for other implementations too. So with a tip of the hat to the old Larry Wall quote about Lazyness, Impatience and Hubris, I would like to suggest what I consider a much simpler route to much better performance: recode it in C++ using both Rcpp (for the R/C++ integration) and inline for the on-the-fly compilation, linking and loading of C++ code into R.
## inline to compile, load and link the C++ code
require(inline)
## we need a pure C/C++ function as the generated function
## will have a random identifier at the C++ level preventing
## us from direct recursive calls
incltxt <- '
  int fibonacci(const int x)  
     if (x == 0) return(0);
     if (x == 1) return(1);
     return (fibonacci(x - 1)) + fibonacci(x - 2);
   '
## now use the snippet above as well as one argument conversion
## in as well as out to provide Fibonacci numbers via C++
fibRcpp <- cxxfunction(signature(xs="int"),
                       plugin="Rcpp",
                       incl=incltxt,
                       body
                       ='
   int x = Rcpp::as<int>(xs);
   return Rcpp::wrap( fibonacci(x) );
')
This single R function call cxxfunction() takes the code embedded in the arguments to the body variable (for the core function) and the incltxt variable for the helper function we need to call. This helper function is needed for the recursion as cxxfunction() will use an randomized internal identifier for the function called from R preventing us from calling this (unknown) indentifier. But the rest of the algorithm is simple, and as beautiful as the initial recurrence. Three lines, three statements, and three cases for F(0), F(1) and the general case F(n) solved by recursive calls. This also illustrates how easy it is to get an integer from R to C++ and back: the as and wrap simply do the right thing converting to and from the SEXP types used internally by the C API of R. A performance comparison of the basic R version fibR, its byte-compiled variant fibRC and and the C++ version fibRcpp shown above is very compelling. We have added a file fibonacci.r to the large and still growing set of examples included with Rcpp, and we can just execute that script with Rscript or (as here) r from the littler package:
edd@max:~/svn/rcpp/pkg/Rcpp/inst/examples/Misc$ r fibonacci.r
Loading required package: inline
Loading required package: methods
Loading required package: compiler
        test replications elapsed relative user.self sys.self
3 fibRcpp(N)            1   0.092   1.0000      0.09     0.00
2   fibRC(N)            1  61.480 668.2609     61.47     0.00
1    fibR(N)            1  61.877 672.5761     61.83     0.02
edd@max:~/svn/rcpp/pkg/Rcpp/inst/examples/Misc$ 
So the recursion for the original argument of N=35 takes just over a minute at about 61.5 and 61.9 seconds, respectively, for the R version and its byte-compiled variant (as per the column titled elapsed). So byte-compilation essentially offers no help for the bottleneck of slow function calls. The C++ versions relying on Rcpp which created in a few lines of code and a single call to cxxfunction however takes just 92 milliseconds---or a relative gain of well over six-hundred times. That provides another nice demonstration of what Rcpp can do. Improved algorithms for well-understood problems are surely one way to accelerate solutions. But there are (many ?) times when we do not have the luxury of being able to think through to a new and improved approach. Or worse, such an approach may even introduce new errors or inaccurracies if we get it wrong on a first try. With Rcpp, we are able to the express the problem as written in its original statement: a simple recursion. The gain relative to a slow R implementation is noteworthy---and could of course be improved further if we really needed to by relying on better algorithms like memoization. But for day to day tasks, I gladly take speedups of (up to) a few hundred times thanks to Rcpp without having to do hard algorithmic work. Before closing, a quick reminder that I will be giving two classes on Rcpp in a few weeks. These will be in New York on September 24, and San Franciso on October 8, see this blog post as well as this page at Revolution Analytics (who are a co-organiser of the classes) for details and registration information.

David Welton: Zero to Profitable - LiberWriter Lessons Learned

Here's how I have created the beginnings of a profitable Kindle formatting and conversion service, LiberWriter, from scratch. Last Winter, I read one of the best business books I have read in a long time, Rob Walling's Start Small, Stay Small: <iframe frameborder="0" marginheight="0" marginwidth="0" scrolling="no" src="http://rcm.amazon.com/e/cm?lt1=_blank&amp;bc1=000000&amp;IS2=1&amp;bg1=FFFFFF&amp;fc1=000000&amp;lc1=0000FF&amp;t=dedasys-20&amp;o=1&amp;p=8&amp;l=as4&amp;m=amazon&amp;f=ifr&amp;ref=ss_til&amp;asins=B003YH9MMI" style="width: 120px; height: 240px;"></iframe> Rather than being a "big idea" book that includes one big idea and lots of stories to support it, it's a very practical book on how to go about creating a small online business. I've always been someone who loves to build things, from various open source projects, to diverse web sites that people have found valuable. However, I am not a "business guy". I'm not that good at making money, so the simple approach in the book is really better for people like me: make something and sell it. Advertising can certainly work, but it's so much harder to figure out the numbers compared with a product, where you can compare the cost of providing the product to the price people will pay for it. And that's just one thing; the book has tons of ideas about practical ways of going about putting together a profitable small online business. It's not a "get rich quick" book - part of the idea is that if you are looking at a niche that is fairly small, it will simply not be of interest to larger companies, so you aren't going to get outspent and outcompeted by them. In any event, though, at about the same time I read the book, I was poking around looking at Amazon's KDP, which allows you to self publish for the Kindle, and noticing how difficult the process is. The native format of Amazon's books is HTML with several XML files thrown in for good measure. Now, for someone technical, that's certainly not an insurmountable obstacle, but for many authors, it's a very unpleasant prospect. Granted, you can also manipulate a Word file to make it suitable for the KDP, but even that is something that many people dont' find to be a productive use of their time. They're authors, and they want to write. Having spotted a niche that looked interesting - I love to read, and I like the idea of helping out authors - I discarded the book idea I was looking at myself and did some writing of my own: source code for a project that would automate the process of converting and formatting Kindle books. The core of the system was a fun evenings/weekends project, and soon it was able to produce pretty good books. After "inflicting" the beta version of the system on several people, such as Rich Bowen (thanks again, Rich!), I got it beat into shape and started accepting the first paying customers. It's very exciting to have those first few people pay for something you made - it's a great feeling! Initially, my thought was to sell it as a way to write books directly for the Kindle, however, it soon became evident that 99% of people have already written their books with Microsoft Word, so what they were really interested in was a conversion and formatting system that would take a Word document, poke and prod, stitch and stretch it some, and output a nice looking book for the Kindle. One of the lessons from Rob's book was that stuff doesn't have to be perfect if it works. Initially, I had people putting their word documents into LiberWriter not with the smooth(ish) upload process we have now, but by cutting and pasting in their documents! As a computer guy, doing things in a hacky way is sometimes very unpleasant, but you know what? It worked, and it was easy for people to handle, so I ran with it until a better system was in place. Writing code was the easy part, and definitely within my "comfort zone". Some of the other things I've had to do have been much more difficult, and as a consequence, more of a learning experience. For instance, I realized early on that the process would never be 100% automatic, so I'd have to get some people to work on the books, with the idea being to provide them tools to make the process as simple, quick, and easy as possible. I'm always on the lookout for new things to script within the system. However, need people it does, and finding them and engaging them has been a difficult process. As per the book's suggestion, I've primarily used oDesk to find contractors, and have grardually begun to find some people who work really well. It has taken time, and has not been easy, though. I'm not an introvert, but in some ways I'm happiest when doing my own thing. Being the 'boss' is new. One of the tricky aspects of oDesk is that pretty much any job posting gets tons of responses, some of them from people who appear to have barely read the posting. One trick I learned is to request that the potential contractor creates an account with LiberWriter. Very simple and not a waste of time, and yet a majority of applicants ignored the request. Through most of the spring and summer, LiberWriter remained something strictly for the evenings and weekends, as I was busy with client work during the days, and with my daughter during the afternoons, but as August rolled around, I found some more time on my hands, and really started investing more energy in LiberWriter. It has been very rewarding to see a corresponding increase in the number of customers. We (at this point, between myself and the contractors, LiberWriter is a group, and no longer "I") also raised prices - another valuable piece of advice from the book, and... pretty much anyone who writes for people jumping into online businesses. As tech people, we often tend to aim low in terms of prices. Indeed, soonish, prices will likely go up again. Another challenge has been turning it as much as possible into a "productized service". Since Kindle books are fairly simple in what you can do with them, as long as you don't get too fancy, it's possible to automate *most* things, but not everything, so it's not just a product that people buy and it works and that's that; there's a human element involved, which means more communication, and more potential for things to go off the rails. I've been investing time in automating the workflow of the system, but have a lot more to do on that front. Also, one of the things our customers love about the service is being able to deal with "real people", something that is more difficult at Amazon. That's good for us in one way, but in the future, it will be critical to document things and make them as simple as possible to avoid generating unneccessary support requests, as it can easily take up a lot of time. Indeed, because LiberWriter does attract customers who are often not all that technical, making the user experience as easy and straightforward for them as possible (and then some) is extremely important. It can be exasperating once in a while, but I do my best to channel any frustrated energy on my part into making the site ever easier and ever more straightforward. In other words, instead of "how the heck do they not get that?!" it's "what can I do to make sure the tools and information they need are even easier for them to get?". There's lots to do on that front, but on the whole it's actually part of the project that I've grown to like a lot. Rather than dealing with other techies like myself, our customers are people who really benefit from what we offer because we can save them so much time and frustration. Marketing the system is fun, but another area where I have a lot to learn: I'm not a natural when it comes to marketing or selling. One thing that has worked well so far is finding forums where your target users hang out, and then.... spam them as often as possible? No way! Be yourself, and provide genuine help and value to people in the forums. By being on the level, and not trying to sell! sell! sell! people are friendlier and more receptive to your message. It can be time consuming, but I suppose it's the sort of thing where taking the wrong short cut could be very detrimental over the long haul. Without disclosing too much, I don't think I'll ever get rich from LiberWriter, but it is incredibly satisfying to have created and marketed a product of my own that goes beyond just selling my own time. LiberWriter doesn't bring in as much as consulting, yet, but it feels like much more of an investment, something that will have some momentum of its own, and of course it has been an incredible learning experience. I like programming, but being outside of my "comfort zone", doing stuff that's new and challenging is also a very positive part of the project. If things continue to grow the way they have been, I could envision depending on LiberWriter as my primary source of income in the very near future. That's a bit of a jump into the unknown in some ways, but I'd love it. I have worked very hard on it lately, and one of the things I am enjoying is always having new ideas about how to improve every aspect of the system, from customer service to the mechanics of the conversion process, to tracking the finances. In some ways it's tiring because I'm thinking about it *all* the time, but it's that "good kind of tired". It's been a tumultous summer, and in the past few weeks we (well, my wife much more than me!) had a new baby boy, and bought a house here in Padova. To keep things interesting for the future, I applied to the Startup Chile program with LiberWriter. I suspect they're more interested in startups with high growth potential, but I feel strongly that the approach outlined in Rob's book is one that people outside of Silicon Valley, without easy access to venture capital and the huge talent pool that area has, should consider, rather than trying to copy what makes Silicon Valley work like it does. Whether I get accepted or not, LiberWriter will continue to grow, and, I sincerely hope, thrive. A big thanks to all our customers, and to my wife Ilenia, and children, Helen and Daniel for tollerating all the time I spend with the computer. I wrestled a bit with writing this post, as I don't want to "jinx things", and I've only just got a small taste of "success", but I've always enjoyed reading about how "ordinary people" have managed to create their own small businesses, people like those behind Balsamiq, "Bingo Card Creator", and the like, and I figure that writing up my own experiences is a way of "paying it forward".

Wouter Verhelst: Why I think MySQL is a toy.

A commentor on my previous post asked why I think MySQL is a toy. I've actually blogged about that a number of times, but when wanting to point that out, I found that most of those posts point out just one thing, rather than having one post that enumerates them all. So let's remedy that, shall we? There are many things wrong with MySQL, including, but not limited to: So it's my opinion that any database which fails to store data correctly in its default settings can't be anything but a toy; or that a database which has a comparatively small feature set can't be anything but a toy. But maybe that's just me. [1] No, I haven't used all those features; but I have used asynchronous notification, sequences (other than for primary keys), kerberos auth, custom data types, and (obviously) I have enjoyed the extra peace of mind of knowing that my database is ACID compliant, meaning that it will either accept my transaction as a whole, or reject it as a whole (but usually the former). In addition, I've seen customers use the table inheritance feature.

Russell Coker: Moving from a Laptop to a Cloud Lifestyle

My Laptop History In 1998 I bought my first laptop, it was a Thinkpad 385XD, it had a PentiumMMX 233MHz CPU, 96M of RAM, and an 800*600 display. This was less RAM than I could have afforded in a desktop system and the 800*600 display didn t compare well to the 1280*1024 resolution 17 inch Trinitron monitor I had been using. Having only 1/3 the pixels is a significant loss and a 12.1 inch TFT display of that era compared very poorly with a good Trinitron monitor. In spite of this I found it a much better system to use because it was ALWAYS with me, I used it for many things that were probably better suited to a PDA (there probably aren t many people who have carried a 7.1 pound (3.2Kg) laptop to as many places as I did). But some of my best coding was done on public transport. But I didn t buy my first laptop for that purpose, I bought it because I was moving to another country and there just wasn t any other option for having a computer. In late 1999 I bought my second laptop, it was a Thinkpad 600E [1]. It had twice the CPU speed, twice the RAM, and a 1024*768 display that displayed color a lot better. Since then I had another three Thinkpads, a T21, a T43, and now a T61. One of the ways I measure a display is the number of 80*25 terminal windows that I can display at one time, my first Thinkpad could display four windows with a significant amount of overlap. My second could display four with little overlap, my third (with 1280*1024 resolution) could display four clearly and another two with overlap, and my current Thinkpad does 1680*1050 and can display four windows clearly and another five without excessive overlap. For most of the last 13 years my Thinkpads weren t that far behind what I could afford to get as a desktop system, until now. A Smart Phone as the Primary Computing Device For the past 6 months the Linux system I ve used most frequently is my Sony Ericsson Xperia X10 Android phone [2]. Most of my computer use is on my laptop, but the many short periods of time using my phone add up. This has forced some changes to the way I work. I now use IMAP instead of POP for receiving mail so I can use my phone and my laptop with the same mail spool. This is a significant benefit for my email productivity, instead of having 100 new mailing list messages waiting for me when I get home I can read them on my phone and then have maybe 1 message that can t be addressed without access to something better than a phone. My backlog of 10,000 unread mailing list messages lasted less than a month after getting an Android phone! A few years ago I got an EeePC 701 that I use for emergency net access when a server goes down. But even a 920g EeePC is more weight than I want to carry, as I need to have a mobile phone anyway there is effectively no extra mass or space used to have a phone capable of running a ssh client. My EeePC doesn t get much use nowadays. A Cheap 27 inch Monitor from Dell Dell Australia is currently selling a 27 inch monitor that does 2560*1440 (WQHD) for $899AU. Dell Australia offers a motor club discount which pretty much everyone in Australia can get as almost everyone is either a member of such a club or knows a member well enough to use their membership number for the discount. This discount reduces the price to $764.15. The availability of such a great cheap monitor has caused me to change my working habits. It doesn t make sense to have a reasonably powerful laptop used in one location for almost all the time when a desktop system with a much better monitor can be used. The Plan Now that my 27 inch monitor has arrived I have to figure out a way of making things work. I still need to work from a laptop on occasion but my main computer use is going to be a smart-phone and a desktop system. Email is already sorted out, I already have three IMAP client systems (netbook, laptop, and phone), adding a desktop system as a fourth isn t going to change anything. The next issue is software development. In the past I haven t used version control systems that much for my hobby work, I have just released a new version every time I had some significant changes. Obviously to support development on two or three systems I need to use a VCS rigorously. I m currently considering Subversion and Git. Subversion is really easy to use (for me), but it seems to be losing popularity. Git is really popular so if I use it for my own projects then I could allow anonymous access for anyone who s interested maybe that will encourage more people to contribute. One thing I haven t even investigated yet is how to manage my web browsing work-flow in a distributed manner. My pattern when using a laptop is to have many windows and tabs open at the same time for issues that I am researching and to only close them days or weeks later when I have finished with the issue. For example if I m buying some new computer gear I will typically open a web browser window with multiple tabs related to the equipment (hardware, software, prices, etc) and keep them all open until I have received it and got it working. Chromium, Mozilla, and presumably other modern web browsers have a facility to reopen windows after a crash. It would be ideal for me if there was some sort of similar facility that allowed me to open the windows that are open on another system and to push window open commands to another system. For example when doing web browsing on my phone I would like to be able to push the URLs of pages that can t be viewed on a phone to my desktop system and have them open waiting for me when I get home. It would be nice if web browsing could be conceptually similar to a remote desktop service in terms of what the user sees. Finally in my home directory there are lots of random files. Probably about half of them could be deleted if I was more organised (disk space is cheap and most of the files are small). For the rest it would be good if they could be accessed from other locations. I have read about people putting the majority of their home directory under version control, but I m not sure that would work well for me. It would be good if I could do something similar with editor sessions, if I had a file open in vi on my desktop before I left home it would be good if I could get a session on my laptop to open the same file (well the same named file checked out of the VCS). Configuring the Desktop System One of the disadvantages of a laptop is that RAID usually isn t viable. With a desktop system software RAID-1 is easy to configure but it results in two disks making heat and noise. For my new desktop system I m thinking of using a DRBD device for /home to store the data locally as well as almost instantly copying it to RAID-1 storage on the server. The main advantage of DRBD over NFS, NBD, and iSCSI is that I can keep working if the server becomes unavailable (EG use the desktop system to ask Google how to fix a server fault). Also with DRBD it s a configuration option to allow synchronous writes to return after the data is written locally which is handy if the server is congested. Another option that I m considering is a diskless system using NBD or iSCSI for all storage. This will prevent using swap (you can t swap to a network device to avoid deadlocks) but that won t necessarily be a problem given the decrease in RAM prices as I can just buy enough RAM to not need swap. The Future Eventually I want to be able to use a tablet for almost everything including software development. While a tablet display isn t going to be great for coding I m sure that I can make use of enough otherwise wasted time to justify the expense. I will probably need a tablet that acts like a regular Linux computer not an Android tablet.

7 September 2011

Soeren Sonnenburg: Shogun at Google Summer of Code 2011

Google Summer of Code 2011 gave a big boost to the development of the shogun machine learning toolbox. In case you have never heard of shogun or machine learning: Machine Learning involves algorithms that do intelligent'' and even automatic data processing and is nowadays used everywhere to e.g. do face detection in your camera, compress the speech in you mobile phone, powers the recommendations in your favourite online shop, predicts solulabily of molecules in water, the location of genes in humans, to name just a few examples. Interested? Then you should give it a try. Some very simple examples stemming from a sub-branch of machine learning called supervised learning illustrate how objects represented by two-dimensional vectors can be classified in good or bad by learning a so called support vector machine. I would suggest to install the python_modular interface of shogun and to run the example interactive_svm_demo.py also included in the source tarball. Two images illustrating the training of a support vector machine follow (click to enlarge): svm svm interactive Now back to Google Summer of Code: Google sponsored 5 talented students who were working hard on various subjects. As a result we now have a new core developer and various new features implemented in shogun: Interfaces to new languages like java, c#, ruby, lua written by Baozeng; A model selection framework written by Heiko Strathman, many dimension reduction techniques written by Sergey Lisitsyn, Gaussian Mixture Model estimation written by Alesis Novik and a full-fledged online learning framework developed by Shashwat Lal Das. All of this work has already been integrated in the newly released shogun 1.0.0. In case you want to know more about the students projects continue reading below, but before going into more detail I would like to summarize my experience with GSoC 2011. My Experience with Google Summer of Code We were a first time organization, i.e. taking part for the first time in GSoC. Having received many many student applications we were very happy to hear that we at least got 5 very talented students accepted but still had to reject about 60 students (only 7% acceptance rate!). Doing this was an extremely tough decision for us. Each of us ended up in scoring students even then we had many ties. So in the end we raised the bar by requiring contributions even before the actual GSoC started. This way we already got many improvements like more complete i/o functions, nicely polished ROC and other evaluation routines, new machine learning algorithms like gaussian naive bayes and averaged perceptron and many bugfixes. The quality of the contributions and independence of the student aided us coming up with the selection of the final five. I personally played the role of the administrator and (co-)mentor and scheduled regular (usually) monthly irc meetings with mentors and students. For other org admins or mentors wanting into GSoC here come my lessons learned: Now please read on to learn about the newly implemented features: Dimension Reduction Techniques Sergey Lisitsyn (Mentor: Christian Widmer) Dimensionality reduction is the process of finding a low-dimensional representation of a high-dimensional one while maintaining the core essence of the data. For one of the most important practical issues of applied machine learning, it is widely used for preprocessing real data. With a strong focus on memory requirements and speed, Sergey implemented the following dimension reduction techniques: See below for the some nice illustrations of dimension reduction/embedding techniques (click to enlarge). isomap swissrollrno kllelocal tangent space alignment Cross-Validation Framework Heiko Strathmann (Mentor: Soeren Sonnenburg) Nearly every learning machine has parameters which have to be determined manually. Before Heiko started his project one had to manually implement cross-validation using (nested) for-loops. In his highly involved project Heiko extend shogun's core to register parameters and ultimately made cross-validation possible. He implemented different model selection schemes (train,validation,test split, n-fold cross-validation, stratified cross-validation, etc and did create some examples for illustration. Note that various performance measures are available to measure how good'' a model is. The figure below shows the area under the receiver operator characteristic curve as an example. foo Interfaces to the Java, C#, Lua and Ruby Programming Languages Baozeng (Mentor: Mikio Braun and Soeren Sonnenburg) Boazeng implemented swig-typemaps that enable transfer of objects native to the language one wants to interface to. In his project, he added support for Java, Ruby, C# and Lua. His knowlegde about swig helped us to drastically simplify shogun's typemaps for existing languages like octave and python resolving other corner-case type issues. The addition of these typemaps brings a high-performance and versatile machine learning toolbox to these languages. It should be noted that shogun objects trained in e.g. python can be serialized to disk and then loaded from any other language like say lua or java. We hope this helps users working in multiple-language environments. Note that the syntax is very similar across all languages used, compare for yourself - various examples for all languages ( python, octave, java, lua, ruby, and csharp) are available. Largescale Learning Framework and Integration of Vowpal Wabbit Shashwat Lal Das (Mentor: John Langford and Soeren Sonnenburg) Shashwat introduced support for 'streaming' features into shogun. That is instead of shogun's traditional way of requiring all data to be in memory, features can now be streamed from e.g. disk, enabling the use of massively big data sets. He implemented support for dense and sparse vector based input streams as well as strings and converted existing online learning methods to use this framework. He was particularly careful and even made it possible to emulate streaming from in-memory features. He finally integrated (parts of) vowpal wabbit, which is a very fast large scale online learning algorithm based on SGD. Expectation Maximization Algorithms for Gaussian Mixture Models Alesis Novik (Mentor: Vojtech Franc) The Expectation-Maximization algorithm is well known in the machine learning community. The goal of this project was the robust implementation of the Expectation-Maximization algorithm for Gaussian Mixture Models. Several computational tricks have been applied to address numerical and stability issues, like An illustrative example of estimating a one and two-dimensional Gaussian follows below. 1D GMM2D GMM Final Remarks All in all, this year s GSoC has given the SHOGUN project a great push forward and we hope that this will translate into an increased user base and numerous external contributions. Also, we hope that by providing bindings for many languages, we can provide a neutral ground for Machine Learning implementations and that way bring together communities centered around different programming languages. All that s left to say is that given the great experiences from this year, we d be more than happy to participate in GSoC2012.

Wouter Verhelst: No more MySQL on my machine

I've said it before: I think MySQL is a toy, and I want as little to do with it as possible. Unfortunately, since the KDE PIM suite depends on akonadi, which depends on a database, which was initially implemented against MySQL, not having MySQL installed on a Debian machine if you want to use the KDE PIM suite, for the longest time, wasn't even possible. Today it is, but it requires some manual steps:
sudo apt-get --purge install akonadi-backend-postgresql akonadi-backend-mysql-
akonadictl stop
rm -rf .config/akonadi
rm -rf .local/share/akonadi
cat > .config/akonadi/akonadiserverrc <<EOF
[%General]
Driver=QPSQL
[QPSQL]
Name=akonadi-wouter
Host=
Options=
StartServer=false
EOF
createdb akonadi-wouter
Change "akonadi-wouter" for a suitable database name. And now it should work. Note that this requires you run PostgreSQL system-wide and create a system-wide database in that server. It should, in theory, be possible to have akonadi run its own private PostgreSQL instance, much like how the MySQL backend does things, but a) I couldn't get that to work, and b) I don't think having each user run their own database server instance is a good idea to start with, so honestly I didn't try very hard. And there, pronto! I now no longer have toy databases on my laptop. Word.

Emmanuel Bouthenot: Sympa in Squeeze Backports

For those interested in Sympa, version 6.1.4 has been uploaded to squeeze-backports. This version fixes around two dozen bugs since the version present in squeeze (6.0.1). I strongly recommend to use this version with squeeze as it fixes some very annoying bugs. How to install it: For squeeze users Be sure to have squeeze-backports repository enabled in your sources.list as explained on Debian Backports website then:
apt-get -t squeeze-backports install sympa
For lenny users For lenny users with a running sympa installation who plan to upgrade to squeeze and use sympa from squeeze-backports, it is recommended to upgrade directly from the version 5.3.4 (lenny's version) to 6.1.4. To do so, you just need to add some apt pinning in /etc/apt/preferences (see below) and then dist-ugprade normally.
Package: sympa
Pin: version 6.1.4*
Pin-Priority: 500
Sympa 6.1.6 is already out and should be uploaded in unstable soon, it should also be backported to squeeze-backports if all goes fine. Special thanks to Gerfried (rhonda) and Alexander (formorer) for their work on Debian Backports.

6 September 2011

Joey Hess: water

This was the second most rainy day of the year, so far. 28 hours of solid rain and counting. Good time to take stock of the water situation here at the cabin after a year's experience. The springs were as seasonal as I'd feared. After running strongly all Spring, the main spring ebbed and died in the Summer months. By mid-July there was no remaining source of potable water. If I had not been away so much over the summer it would have been worse. As it was, I needed only twenty gallons of water hauled from neighbor Lee's well. The large cistern was filled in a single night during the most rainy period this Spring, and provided wash water for two months of the summer, and that only lowered it by a quarter. So I could have been less sparing with it, and not relied so much on rain water catchment for supplimental wash water. Today I replaced the pump, so I can use the pressure tank and have running water in the house. I could have done this earlier, but what can I say; I enjoy hauling buckets of water, when it doesn't involve breaking ice. In the winter when there's firewood to haul instead, I'll enjoy the indoor plumbing. Also today, I may have finally fixed the pipe to the large cistern properly, so it won't only fill at the heaviest rain times. Along with the ability to cross-pump water from the small to the large cistern, it should be easier to keep it filled, and I might be able to reduce the turbidity enough that it's potable eventually. Will see. I don't live in a dry region, but this is a relatively dry place for the area. It's been interesting to get a taste of what it'd be like to live somewhere where water is actually scarce.

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