Jul 20 2014

Book cover

Title: The Art of LEGO Design
: Jordan Schwartz
Editorial: O'Reilly


Books with step-by-step instructions and easy tutorials there are many. This title goes the opposite, providing us with general techniques, hints and ideas, but showcasing the works of many authors along its 13 chapters.

From the basic foundations of how to create smooth surfaces, how to build angles, or keeping always a scale in mind, to advanced and great looking mosaics, scenarios or even monsters and spaceships, this book is not only an eye-opener of how pros create such amazing LEGO structures, but also a nice source of inspiration with the abundant photos.

One might actually desire more details of some specific models; For many the closeup images hint how it might have been built, but for the most complex ones you can only imagine how hard has been to construct. But as there are many small interviews with expert designers (apart from the author itself), you at least get some tips from them on how they approach new projects.

I really liked the theme-based chapter structure, allows for quick reference checks, it includes some (but few) detailed instructions for joints and techniques like studded spheres and for amateurs like me it really provides a great boost to imagination on how to try more advanced designs.


As always, you can find all my book reviews at its section.

Jul 10 2014

I entered my LinkedIn to do some cleanup of contacts and I noticed that I've passed the 12 years working mark, so why not a small recap to see how bad life has treated me regarding programming languages?


I've worked at 8 companies since 2001: Alhambra-Eidos, Surfernet, Grupo Raxon, ilitia, Navteq, Tuenti, Minijuegos and CartoDB (current one).

Of those, I did consulting services at two of them, the rest being product development. A bit below 5 years of doing quite varied and interesting consulting projects, but also sometimes feeling Dilbert's strips are so accurate.


Lowest record is 4 months ar Alhambra-Eidos, because was during the summer and they couldn't offer me a part-time job.


Highest record would be Tuenti or ilitia with 4 years, but really the closest one was ilitia, as I left the company just 3 days before the 4th anniversary.


I've coded in*: Visual Basic 6.0, Visual Basic .NET, ASP 3.0, ASP.NET, C++, C#, Java, Javascript, PHP, OO PHP 5.3 **, Ruby.
I'm still in love with C#, Windows might not be the best platform but the language itself is so good that even Java copies its features now.


I've used more or less extensively the following DBs: SQL Server, MySQL, PostgreSQL.
None of them is perfect, all have caveats.


I've used quite a few SCM: Visual SourceSafe, CVS, Subversion, Mercurial, Git.
All of them screw up merges sometimes, but I like Git now that I know a bit and can compare it to Hg.


I've given 18 talks a total of 23 times.
And I still get quite nervous every time I have to do one.



Let's hope 12 years in the future we're not all coding in Javascript. Or maybe we'll be?


* : Only counting professional work of at least a few weeks

** : One thing is coding in PHP and other is writing proper, object oriented, namespaced code

Jun 22 2014

Python is a language that slowly is awakening my curiosity. Widely used, generally appraised and apparently powerful and yet easy to use.

After poking with it at work last friday to convert some JSON data to GeoJSON I decided to build a small tool only with Python (2.7): A script that, given a list of URLs, tells me if any of them has changed since last time it ran.

The source code of the results can be found at my Github; 83 lines of code counting (few) comments. Nothing really cool, in fact it is really simple, but it's a nice exercise as it touches some areas:

  • Methods
  • Managing Arrays (Lists in Python) and Hashmaps
  • Nulls handling ("None" here)
  • Reading and writing files, detecting if a file exists
  • Exception handling
  • JSON parsing and dumping
  • Basic HTTP requests/responses
  • Colored output *


I need to learn more about this language, maybe on the inminent vacations...


* Couldn't resist to add some colors, even if meant adding a library (colorama). And thanks to this I've also learned how to globally install Python libs.

May 14 2014

Computer RAM grows quite fast, but unlike hard disk space no matter how much you have, your applications or services will always require (or benefit) from more.

When you handle big datasets (between few hundred megabytes and few gigabytes) you have to be very careful with how you handle the data, because it is easy to create a point of failure due to out of memory errors. Especifically, you have to check that your code does not fully load into memory datasets if those can be big.

A real world scenario: CartoDB's Import API and a growing list of customers who upload datasets near or above the 1GB threshold. Monit was killing the worker jobs of those big uploads so we had to fix it.


First, diagnostics: At what points the code was fully loading the file?

- It wasn't upon importing the data into PostgreSQL, because that's done via command line and from ogr2ogr.

- It could be Rails, because its documentation only includes a basic "dump uploaded contents" example without even mentioning that you actually have saved the uploaded file in the folder specified by Pathname.new(params[:file]) (or :filename).

- It could be Typhoeus Ruby gem, because we have a Downloader class that fetches contents from urls and writes them into a file. We were doing a full single response_body dump while Typhoeus allows for streaming chunks of the response.

- It could be also AWS S3 Ruby SDK, because we upload there the import files so that workers can fetch them no matter in which server they are spawned. In this case, the documentation is great and it is a one-liner to write into an S3 object streaming a file.


All the 3 "could" were actual failure points, so I applied the fixes and job done. Now I have to spend some time (and bandwith) to upload some multi-GB datasets to benchmark and find where are our new limits in the platform :)


Bonus point: Upon uploading the file using Rails, anybody who hasn't set AS3 credentials on their CartoDB installation would get a different code execution path in which indeed the file is loaded and written once. That's acceptable, but I noticed that deactivating my credentials and testing that path, even after the HTTP request was fully processed, my Linux got around 1GB of RAM in use by Ruby process, suspiciously like the size of the file I uploaded.

After some debugging I dound I had to force MRI 1.9.3's shitty garbage collector to recognize the variable holding the file data as destroyed in order to regain my GB of RAM upon ending the request (filedata = nil). It's fun and sad at the same time that you get away from unmanaged languages to end up needing to do the same resource management techniques.


If you want, you can check all the changes I did to the Ruby code in this pull request.

May 06 2014


Taking advantage of the nights of last week small holidays, I've read a book about game development, but not from the coding point of view. Stay awhile and listen talks about the story of Blizzard Entertainment, the videogame company who created Warcraft, Starcraft and Diablo, with a special focus on the later one.

If you find the topic interesting, head over my book reviews section to check it out.

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