Majek's technical blog

Memcached protocol is not enough

2009-06-01T16:38:00.002+02:00

For some time I'm trying to hack together a prototype of real-time-full-text-search-engine (RTFTSE!). I used a memcached-binary protocol as a communication protocol between backends and storage-nodes.This is a pretty nice protocol and in fact there are strong reasons not to use ascii memcache protocol.

The ministry of strange syscalls

2009-05-19T13:57:00.003+02:00

My favorite syscall today:$ man 2 readahead"readahead() populates the page cache with data from a file so that subsequent reads from that file will not block on disk I/O."I don't really know when should I use that, but it sounds cool. Just an implementation of prefetching on yet another layer. Wait a moment..."readahead() blocks until the specified data has been read. "I'm lost. If it blocks,

GIT is ahead of SVN!

2009-05-18T16:13:00.005+02:00

Git is the most popular DVCS right now. Google trends confirms that:But the interesting fact is that Git is for the first time ahead of its grandpa Svn:Though it's worrying that CVS is still alive, it should be dead ten years ago. Hopefully we can see a process of slow death, the end is inevitable:

QCon mini InThe Brain session

2009-03-10T15:54:00.002+01:00

I'll be speaking about simplified Etherpad clone at QCon London on Wednesday, March 11th.The presentation will take place at Skillsmatter stand (booth number 10), at 16:45.

Evserver, part3: Simplified Etherpad clone

2009-03-04T14:52:00.005+01:00

This time I hacked together few open source projects. The result of my work, except from few minor bugs, seems to be working.I don't know what shall I do with this project next. There are few possible options:throw it away and forget about itadd support for markups other than reStructuredTextimplement new features, like private documents or downloading the rendered markup in different

EvServer, part2: Rabbit and Comet

2009-02-18T00:25:00.003+01:00

sourceI just published the next part of the EvServer story.I'm working at the third part. Though, my major concern is that I'm running out of proofreaders.

EvServer, Introduction: The tale of a forgotten feature

2009-02-06T19:42:00.003+01:00

This article about EvServer doesn't really show it as an innovative piece of software. I hope that future articles will.It seems that the most important thing in this post is a blinking exclamation mark.BTW, ItBlog seems to be dead. For historical reasons I placed my old posts from that blog here, here and here.

I was wondering how Twitter search works

2009-01-22T01:02:00.003+01:00

Few days ago I committed a blog post about Twitter search.As a matter of fact, I'm not sure what is the solution to the question I asked there. On the other hand I presented some interesting (at least for me) numbers.While writing this stuff I learned a lot and maybe this blog post will be a motivation for someone to actually create such a perfect system.I'm still thinking about the persistence

Asynchronous libraries performance

2008-12-15T18:06:00.004+01:00

I committed next post on LShift's blog.BTW. This is my 100th post in this blog!

Nmap Book finally released!

2008-12-06T15:03:00.003+01:00

I'm really excited. After years of work Fyodor finally managed to finish The Book "Nmap Network Scanning". It should be a great gift for every security geek. You can preorder it on Amazon for 34$.

AMQP? Maybe not yet. At least not with Python.

2008-11-21T15:43:00.005+01:00

sourceIn my last Python project I thought about using AMQP messaging. A quick look at Python AMQP libraries shows two possibilities:Apache Qpid python clientBarry’s py-amqplibBoth libraries are developed tightly with their brokers: Apache uses Qpid, py-amqplib uses RabbitMQ.Apache QpidI started my adventure by downloading the source. They don’t have binary packages so this is what’s needed:$

How to escape from blocked unactivated Vista

2008-11-18T19:16:00.009+01:00

Few times I was pissed off by this screen:It means that I haven't activated Vista on time and Microsoft stopped liking me. The problem is that at least two times I was caught by this screen when I haven't got access to the net. I had password to WiFi, but haven't entered it yet. When Vista is blocked you don't have access to any networking settings so the password is useless. Yet another time,

Tracing Python memory leaks

2008-11-17T06:23:00.001+01:00

Tracing Python memory leaks.

Simple inter-process locks

2008-11-11T01:40:00.003+01:00

At LShift blog I wrote about simple inter process locks in Python.

Youtube - a team of highly trained monkeys...

2008-11-10T13:53:00.002+01:00

In translation "A team of highly trained monkeys has been dispatched to deal with this situation."I'm not the only one to see this message. I think it's even better than "you broke reddit" message.

Jukebox XSRF

2008-11-04T02:29:00.005+01:00

sourceIn Lshift we use Tony’s erlang jukebox, it's great, anyone can play music at the office. I found XSRF there and exploited it maliciously. Every time someone from inside the office opens this blog, Britney is being played.The exploit is not especially complicated:

Blog success story

2008-11-02T04:00:00.010+01:00

sourceThe beginningsI wrote first post in this blog 22 months* ago. My intentions weren’t clear. I wanted to document my ideas (I had a lot of them), have a place to store code snippets and maybe promote myself.First posts I wrote in Polish and didn’t really know if I will be able to write in English. When look at my first posts, I start to understand that they were just testing the territory. I

Innovation is illegal

2008-09-09T21:48:00.006+02:00

New, interesting technologies on the web are often criticized, sued and sometimes even ruined by the court rulings. There are a lot of lawsuits on new technologies.Let's bring a few important technologies that were(are?) considered illegal by some people:Google (and other search engines) - deep linking. I remember the days when people said that deep linking is not fair. There were even court

Presentation: Nmap and asynchronous programming

2008-08-28T13:00:00.000+02:00

In this presentation I would like to talk about my adventure with extending Nmap and what I learned from it regarding asynchronous programming.Nmap is a port scanner with many other features.On this slide you can see an example of Nmap output.It shows open tcp ports on some target machine. It also shows service type (if it is ssh or http or something else) and version of a daemon running behind

Presentation: hacking Industrial Robots

2008-08-26T12:51:00.001+02:00

I'll talk about my work on industrial robots. The robots belong to my university - PJIIT.Here you can see our two Motoman SK6 robots. They were bought by the Japanese government from a fund to support developing countries. The robots were produced in Japan, assembled in Sweden, serviced by Germany and located in Poland.They are created to do welding and painting in the industry. They have no

Learning Erlang

2008-08-24T16:09:00.010+02:00

I mentioned before that I'd love to learn Erlang. Just before my holidays in mountains the Erlang book has arrived. I had to chose between the holidays and learning Erlang. I chose both.It was very nice to read it on the meadows at the top of the hills. But the book is rather heavy when you need to carry it uphill.I think it's one of the best written computer books I've ever read. I've learned a

Don't you need an employee?

2008-07-11T21:30:00.006+02:00

(image stolen from that guy, he's also looking for a job)I’m currently looking for a job.What job I’m looking for? I have no idea. I did some things in my life, but that doesn’t mean I want to do them again. Most people think: “well, you’re a python hacker, so here is a python job for you!”. That’s just wrong. I want new challenges, I want to learn.There are probably a lot of things that I could

Ideas are free

2008-07-03T12:43:00.007+02:00

Ideas are free, so here’s the list of mine (previous ideas here).I still think that the next big thing is an open social network, so that anyone can write an extension to it. Something like Facebook api, but hosted on a provider side. That’s why I believe in GAE. Open and easily extendable social network is the web3.0 for me.The new idea is to create a Reddit tracker. When you submit something to

Motoman robot controlled by two Wiimotes

2008-06-15T16:53:00.008+02:00

Some time ago I controlled a robot with a Haptic.Inspired by Johnny Chung Lee I started to work on controlling the Motoman industrial robot using two Wiimote infrared cameras. It's a bit less accurate method than using Haptic, but it's much cheaper.What you need:a robot (or whatever you'd like to control)two Wiimote devicesa software (okay, here's the source, but beware, it's beta, work in

LinkedIn graph - I don’t get it

2008-06-06T11:25:00.004+02:00

At Grono.net, the network graph had more than 80M edges and about 1.2M nodes. You know how much RAM it used on the machines? 320MB. It’s a bit more than 4 bytes for an edge, because of alignment, plus few megabytes of index.LinkedIn says they need 12GB RAM for keeping their graph with 120M edges. Wow. It’s 107 bytes for an edge! I think that the graph shouldn't consume more than 0.5GB RAM.Their