internal fragmentation

a personal journal of hacking, science, and technology

BDFL chooses Mercurial?

Mon, 30 Mar 2009 11:33 by mpm in mercurial (link)

Looks like Guido van Rossum, Python’s Benevolent Dictator For Life, has chosen Mercurial for future Python development. More here.

Forthcoming Mercurial book from O’Reilly

Sun, 29 Mar 2009 18:50 by mpm in mercurial (link)

Bryan O’Sullivan has finally announced that his excellent Mercurial book has been picked up by O’Reilly. Naturally, it will continue to be available under an open license.

Mercurial dropping Python2.3 support

Thu, 26 Mar 2009 09:36 by mpm in Uncategorized (link)

I’ve just announced that Mercurial will be dropping support for Python2.3 with our 1.3 release in July. I’ve been rather reluctant to do this on the general principle that applications (and programming languages in particular!) should be stable enough to be usable over, say, 5 years. But it’s now gotten to the point where Py2.3 hasn’t been available in Debian for two whole releases (in other words, forever), so I can’t actually test against it without building my own copy of Python.

On the upside, this means we’ll get to start using a small handful of nice features added in Python 2.4. Namely decorators, sorted(), and generator expressions.


Thu, 12 Mar 2009 20:38 by mpm in Uncategorized (link)

There’s a lot of buzz going around about these videos, but really, you shouldn’t miss them. Especially this one.

A quick aside about Linux and Youtube: I’ve had mixed results with swfdec for in-browser viewing, so I often use clive to download videos and view them outside my browser (and nicely buffered). I find “xsel | clive” is quite handy to grab a link I’ve copied to the clipboard.


09:55 by mpm in Uncategorized (link)

The Mario Kartel is pleased to announce Puzzle Quest 4: Your Princess Is In Another Castle.

Twin Cities Makers

09:40 by mpm in Uncategorized (link)

Dropped in on the first official meeting of the Twin Cities Makers. Seems like a fun group, even if they like to use webforums. Also, it took about an hour and a half of free-ranging gabble before we actually settled down to some business.

Candle Power

Fri, 6 Mar 2009 01:49 by mpm in Uncategorized (link)

My local green-oriented coffee shop has started putting out candles at dinner time. It struck me as odd that they still thought burning things for light was green, so I’ve decided to do the math on their power efficiency and carbon impact.

A typical votive candle is about 2 ounces of paraffin and burns for about 15 hours. Its brightness is approximately 1 candela or 12 lumens and consumes power (in the form of paraffin fuel) at a rate of about 40W. That’s one or two (or 15!) laptops’ worth of power per candle.

Paraffin (like most fuels) is nearly all carbon by weight and when burned it generates more than its weight in carbon dioxide (12 atomic units of carbon from the candle + 32 atomic units of oxygen from the air per CO2 molecule). About .2kg total or about 13g per hour. Not much, but put a couple dozen of these out every night for a year, and you’re beginning to talk about a substantial amount of carbon.

Now let’s compare this to a 14W compact fluorescent bulb (as bright as a 75W conventional bulb). This generates about 840 lumens of light. That’s equivalent to 70 candles. If we hooked this up to a dirty old coal-fired power plant (generating 1050g of CO2 per kWh), we’d generate about 14.7g of CO2 per hour – almost the same as our candle! If instead we used wind power (readily available in Minnesota) and include the amortized impact of building the wind turbines (something like 22g/kWh worst case), that drops to less than .3 grams per hour.

In other words, the global warming impact of candles is on the order of 60 to way more than 3000 times worse than fluorescent lighting for the same amount of light.

This doesn’t consider heat though. In the winter, a candle is quite an efficient heat source as almost all of its energy is converted to heat. So we end up with 13g of CO2 per hour per candle to get 40 watts of heat. That same heat from an electric heater powered by our coal worst-case would result in 42 grams of CO2/hour. But with wind power, it’d be less than 1 gram of CO2 per hour in the worst case.

In the summer, there’s no upside: candle heat battles against air conditioning. A single candle produces enough heat to cancel out more than 1% of a so-called “ton” of refrigeration (12000 BTUs / hour).

Lastly, we should look at production cost and impact. Light bulbs of any variety almost certainly win, simply because they have lifespans of thousands of hours and are so much brighter. It would take something like 45000 candles to match both the brightness and lifespan of our typical CFL bulb.

So wish for a greener tomorrow and blow out those candles.

Mercurial 1.2

Wed, 4 Mar 2009 22:50 by mpm in Uncategorized (link)

Mercurial 1.2 went out the door a bit ago. It’s the first release following our time-based release plan. All in all, it went pretty well, though I did have to delay a few days so that we could get some test builds made. Hopefully by 1.3 (due July 1st), test builds for most platforms will be automated.