When an English speaker is drowning in details that make the big picture hard to see, she might complain, “I can’t see the forest for the trees.”
image credit: Miguel Virkkunen Carvalho (Flickr)
It’s an odd expression, partly ironic and partly humorous. When I hear it, I sometimes think of my sister, who, after moving from Indiana to Utah, complained that the mountains were getting in the way of her view. (Her tongue was firmly in her cheek… :-)
The expression also describes an important problem of software engineering–one that a lot of engineers don’t understand well enough. It’s a problem with generalization. Continue reading →
I just finished the nastiest debugging experience of my career–nearly 3 weeks on a single bug. After days and days of staring at code, swearing at core dumps, tailing logs, connecting to gdbserver via a multi-hop ssh tunnel from inside a secure environment, and general programmer misery, I felt like doing cartwheels when I finally figured it out, tweaked a few lines of code, and observed stability again.
Hindsight teaches me this lesson: undocumented, unhandled constraints waste enormous amounts of time and energy. If you’re interested in writing good code, you must know your limits, and you must communicate them. This especially matters when the constraints are obscure or surprising.
When I was a technical director at Symantec, I had to formally certify at the end of each quarter that I had not entered into any “side agreements” with customers.
A side agreement is any arrangement that takes place out-of-band, off-the-books, or using private channels not normally examined by accountants. In business, they are usually a bad thing; they can be used to build Enron- or Madoff-style house-of-cards revenue pipelines that are gleaming and glittery at first glance, but that are ripe for collapse because they’re full of hidden caveats and preconditions.
The former Enron towner, now owned by Chevron. Image credit: DaveWilsonPhotography (Flickr)
The problem of side agreements might not impinge on the consciousness of software engineers much, except when they grumble that sales or execs or product management is “selling the roadmap” instead of shipping features. But would you believe me if I said that engineers perpetrate their own Enron-esque side agreements all the time?
Today I’m channeling my inner grumpy old man. And these guys are helping. (I am not old enough to pull off such a face by myself, although life is rapidly helping me get there. ;-)
The reason I’m feeling grumpy is that I’ve had another in a long, long line of conversations about how to write faster code.
It’s not that optimization experts are dumb. Far from it. They are invariably smart, and in general, they are better informed than I am about how pipeline burst cache and GPUs and RAM prefetch algorithms work. I generally learn a lot when I talk to guys like this.
No. What’s making me grumpy is that after decades of hard work, we still have compilers that encourage a culture of black magic and superstition around this topic. I thought I signed up for computer science, not voodoo.
To show you what I mean, let’s talk about the humble inline keyword in C and C++. The amount of FUD and nonsense around it is really unfortunate. How many of the following have you heard? Continue reading →