I’ve been on vacation for the last few days, and while I was (mostly) gone a few interesting things seem to have happened here on the blog. The first is that, after a totally unremarkable first week, my article It’s Faster Because It’s C suddenly had a huge surge in popularity. In a single day it has become my most popular post ever, more than 2x its nearest competitor, and it seems to have spawned a couple of interesting threads on Hacker News and Reddit as well. I’m rather amused that the “see, you can use Java for high-performance code” and the “see, you can’t…” camps seem about evenly matched. Some people seem to have missed the point in even more epic fashion, such as by posting totally useless results from trivial “tests” where process startup dominates the result and the C version predictably fares better, but overall the conversations have been interesting and enlightening. One particularly significant point several have made is that a program doesn’t have to be CPU-bound to benefit from being written in C, and that many memory-bound programs have that characteristic as well. I don’t think it changes my main point, because memory-bound programs were only one category where I claimed a switch to C wouldn’t be likely to help. Also, programs that store or cache enough data to be memory-bound will continue to store and cache lots of data in any language. They might hit the memory wall a bit later, but not enough to change the fundamental dynamics of balancing implementation vs. design or human cycles vs. machine cycles. Still, it’s a good point and if I were to write a second version of the article I’d probably change things a bit to reflect this observation.

(Side point about premature optimization: even though this article has been getting more traffic than most bloggers will ever see, my plain-vanilla WordPress installation on budget-oriented GlowHost seems to have handled it just fine. Clearly, any time spent hyper-optimizing the site would have been wasted.)

As gratifying as that traffic burst was, though, I was even more pleased to see that Dan Weinreb also posted his article about the CAP Theorem. This one was much less of a surprise, not only because he cites my own article on the same topic but also because we’d had a pretty lengthy email exchange about it. In fact, one part of that conversation – the observation that the C in ACID and the C in CAP are not the same – had already been repeated a few times and taken on a bit of a life of its own. I highly recommend that people go read Dan’s post, and encourage him to write more. The implications of CAP for system designers are subtle, impossible to grasp from reading only second-hand explanations – most emphatically including mine! – and every contribution to our collective understanding of it is valuable.

That brings us to what ties these two articles together – besides the obvious opportunity for me to brag about all the traffic and linkage I’m getting. (Hey, I admit that I’m proud of that.) The underlying theme is dialog. Had I kept my thoughts on these subjects to myself or discussed them only with my immediate circle of friends/colleagues, or had Dan done so, or had any of the re-posters and commenters anywhere, we all would have missed an opportunity to learn together. It’s the open-source approach to learning – noisy and messy and sometimes seriously counter-productive, to be sure, but ultimately leading to something better than the “old way” of limited communication in smaller circles. Everyone get out there and write about what interests you. You never know what the result might be, and that’s the best part.

(Dedication: to my mother, who did much to teach me about writing and even more about the importance of seeing oneself as a writer.)