Peter Seibel - Coders at Work - Reflections on the craft of programming

Seibel:The flip side of that these days is…

Fitzpatrick:Programmers’ time is worth more and all that crap? Which can be true. This is true for a small number of machines. Once you get to a lot of machines, all of a sudden the programmers’ time is worth less than the number of machines that this will be deployed against, so now write it in C and profile the hell out of it, and fix the compiler, and pay people to work on GCC to make this compile faster.

Seibel:But even Google uses C++ rather than assembly, so there’s some point at which trying to squeeze the maximum performance isn’t worth it. Or is the theory that a good C++ compiler generates better code than all but the most freakishly rare assembly coders?

Fitzpatrick:We still have some stuff in assembly, but it’s very rare. We have profiling for lots and lots of stuff and it has to really be justified to rewrite it even from Perl to C, and then from C to assembly. Even if it’s all x86, there are all different variations of x86. Do you really want to write assembly for every variation of x86? This one uses SSE 2 and that one uses SSE 3.1. Let the compiler deal with it.

Seibel:You learned to program from programming manuals when you were a little kid. Are there any books that you strongly recommend to new programmers now or think that everyone should read?

Fitzpatrick:Back when I was doing Perl—even for people that knew Perl really well—I would recommend MJD’s Higher-Order Perl . The book is really fun in that it starts somewhat simple and you’re like, “Yeah, yeah, I know what a closure is.” And then it just continues to fuck with your head. By the end of the book, you’re just blown away. Even though I knew all that stuff, in theory, just watching it taken to the extreme really changed how I thought. I recommended that to a bunch of my friends and it blew their minds. In general, any book that gives people a different style to think in. That’s the most recent example I can think of.

Seibel:I see you’ve got The Art of Computer Programming up there; it doesn’t look too worn. How much of it have you read?

Fitzpatrick:Oh, I didn’t get it until less than five years ago, maybe five years ago. I bounce around and read parts of it for fun. But at the time I got it, I had already learned a lot of it through C.S.. So it probably would have been more valuable early on, but I didn’t really know about it prior to the Internet.

Seibel:How much math do you think is necessary to be a programmer? To read Knuth and really understand it, you’ve got to be pretty mathematically sophisticated, but do you actually need that to be a programmer?

Fitzpatrick:You don’t need that much math. For most programmers, day to day, statistics is a lot more important. If you’re doing graphics stuff, math is a lot more important but most people doing Java enterprise stuff or web stuff, it’s not. Logic helps and statistics comes up a lot.

Seibel:You obviously still enjoy programming. But reading some of your LiveJournal entries from when you were in college, it seems like there were times when you were pretty stressed out and hating computers.

Fitzpatrick:Oh, well, I always hate computers. I don’t think we’ve really made any progress in quite a long time. Computers seem slower, and crashier, and buggier than ever. But I’m such an optimist, I keep thinking that they’ll get better. It seems like my computing experience was happier ten years ago than it is today. It seems like my computer was faster ten years ago; like my computer worked better ten years ago. Things have gotten faster but the software has gotten slower and buggier in the meantime.

Seibel:Why do you think that is?

Fitzpatrick:I don’t know. Has the bar been lowered? Or are computers faster so you don’t need to be efficient or you don’t need to know what you’re doing? I have no clue. Some combination of all of the above, or maybe there are so many layers of abstraction that people don’t know what the hell is going on underneath because the computers are so damn fast that it hides your stupidity.

Seibel:So maybe things are not as fast as they ought to be given the speed of computers. But ten years ago there was no way to do what people, as users, can do today with Google.

Fitzpatrick:Yeah. So some people are writing efficient code and making use of it. I don’t play any games, but occasionally I’ll see someone playing something and I’m like, “Holy shit, that’s possible?” It just blows me away. Obviously, some people are doing it right.

I guess I’m mostly dissatisfied with the state of my desktop. It seems like there is a lot of good interesting stuff going on in the back end. But as I’m using my computer I’m more and more frustrated with it. It seems like my Mac shouldn’t have a beach ball spinning all the time.

Seibel:Do you have any interest in writing better desktop software?

Fitzpatrick:The problem is, no one uses it. You want to write stuff people use, which comes down to web apps. I lost my laptop the other day and people were like, “Oh, my God, did you lose stuff?” I had no files on there. It was an Internet terminal. And it was an encrypted disk so I’m not worried about my password or cookies or anything like that. People won’t download programs, I don’t think.

Seibel:Are you more motivated by having users or just by the fun of programming?

Fitzpatrick:There’s definitely some stuff I write for me and I write it explicitly for me as the only user and I could care less if I get patches and stuff. But a lot of times I want to work with other people. Having users is a key to getting contributors. More users find more bugs and find more use cases. It’s more fun to work with other people, especially on open source stuff.

It always feels good when someone writes in to tell you, “Hey, we’re now using your software for x .” That’s pretty cool. When I see the number of web sites that use memcached or the load balancer or something, I’m like, “Ah, that’s cool.” I remember all these porn sites started telling me they’re using my file system. Well, that says something. I’m helping serve up porn. On Craigslist, every request goes through a web server that is basically a front end to memcached. OK. That’s cool.

Seibel:Do you think programmers are overenamored of new things? New languages, new tools, new whatever?

Fitzpatrick:They might be. I don’t know if that’s desperation in hoping the new thing doesn’t suck, like the new programming language does what we all want. But users are the same way. Users always like to get the one with the higher version number even if it sucks more.

I don’t know if programmers are statistically different than humans in general. New must be better. Which is not always the case, but people hope it is. They want it to be.

I remember talking to my dentist a while back and she was going on and on about, like, the advances in dentistry over the last, like, five years, and she was really excited about them.

Seibel:A lot of being a modern programmer requires finding the right pieces that you need to use and understanding them just well enough to use them. How do you deal with that?

Fitzpatrick:CPAN has everything. There are 14 ID3 parsers. Pick one.

Seibel:So that, in a way, is the problem facing the modern programmer—there are 14 of them. How do you pick?