Jay Lake's "Rocket Science"

Last time I checked, the list of people who had it in for me included Nazis, Commies, the Kansas City Mob, the United States Army, the Augusta Police and the Butler County Sheriff's Department. Not to mention Mr. Bellamy's gang, Doc Milliken and Lois. I was sure I'd left someone off the list, but I figured they'd let me know in due time.

—Rocket Science by Jay Lake.

I seldom read non-fiction, on the grounds that the Universe has a ≅14 billion year head start on me, and that leaves me with a lot to learn and not a lot of time to do it. But I've always had a soft spot for science fiction, and, months back, when an old friend, Jay Lake, sent me a link to a press release announcing that he'd just signed a contract for his second and third novels, my immediate reaction was "when did you have a first novel?" Let your friends move out of town, and little details like that start getting lost, apparently. He filled in the blanks for me, and I ordered a copy of Rocket Science immediately. I must admit, however, that I don't always enjoy Jay's writing. The skill and intelligence he brings to his craft are always evident, but the style and subject don't always appeal to me. Just a personal thing.

Jay and I met in 1986, working jobs that eventually payed about a buck over minimum wage. We were both in on the ground floor of the desktop publishing revolution, not that that meant a lot at the time. I was developing Mac software in my spare time and periodically interviewing for jobs in the Microcomputer Support Group in UT Austin's Computation Center. Jay was writing sporadically, and I can't remember what else. One thing about the kind of guy Jay was: with both of us basically living paycheck to paycheck, he was the sort of fellow who'd find our boss working herself up to firing me over one or another of my pointed critiques about the way our operation was run, and he'd tell her that I had a point, and if I was fired, he'd quit. Probably saved my job a couple of times that way. And I always had to hear about it from somebody else. You've got to respect a guy like that. And he was amazingly smart, had already lived a very odd life which gave him a fascinating perspective on things, and was a thoroughly nice guy. It's easy to end-up friends with a fellow like that.

So, an old friend like that gets his first novel published, and I think you pretty much have to go buy a copy and read it. And I'm glad I did. It was a hoot - the quickest read I've had in a long time. It's sci-fi set in post-World War II Kansas and centers around a mild-mannered fellow who quite unexpectedly crosses paths with a super-secret aircraft stolen from the Nazis right under the noses of Army Intelligence. Mayhem ensues. It's fun. Recommended.

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Other recent-ish page-turners: The Soviet Space Race with Apollo, A World Lit Only By Fire, and Tales of a Shaman's Apprentice.

Conflating Atomicity with Thread-Safety

I've been adding a thread pool to Qwicap (in the unreleased version 1.4a40), and, with it, a lot of machinery for gathering information about the pool, the threads, the rate at which they're processing hits, etc. The thread pool implementation, of course, depends on careful use of synchronization for its correctness. Because synchronization can be costly, I tried to minimize its use in the information gathering machinery. I thought I had a lot of scope for such minimization due to the fact that operations on Java primitives that occupy 32 bits, or less, are atomic. So I did things like declaring various counters as "int" types and using the increment operator to change them, e.g. "ThreadCount++;", without bothering to execute them inside an appropriately synchronized block.

Very quick, but, during testing I soon realized that it was also very wrong.

A run of javap made the problem obvious. The "ThreadCount++;" statement, where "ThreadCount" is an instance variable, compiles into the following Java instructions:

   2:   getfield        #2; //Field ThreadCount:I
   5:   iconst_1
   6:   iadd
   7:   putfield        #2; //Field ThreadCount:I

Each of those instructions is operating on an integer primitive, and is therefore operating atomically, but, of course, there are four instructions, and if other threads are executing any of the same instructions at the same time, you can lose the effect of one or more of the increment operations. So, operations on 32-bit, and smaller, primitives are atomic in the JVM, but this fact does nothing to help you avoid synchronization.

My dim recollections of 68000 assembly language programming seem to have steered me in the wrong direction in this case, by leaving me convinced that an operation as simple and common as "ThreadCount++;" would probably be represented by a single instruction. Wrong. And returning to my 68000 documentation, I see that I must have been thinking of facilities like the "address register indirect post-increment" addressing mode, which was nifty, but also wouldn't have allowed that increment operation to be represented as a single 68000 instruction. Wrong again. That'll teach me.

By the way, am I the only old C programmer who wishes from time to time that the "asm" statement had been carried over into Java? I mean, once you have a platform independent assembly language, why not? I admit that the practical value would be low, and code readability would suffer, [OK, that's two good "why nots" right there] but I'd have found it very educational. Having actually used the JVM instruction set (which I wouldn't have been able to resist), rather than having merely read about it, I certainly would have known better than to believe that my increment operation would execute atomically.

Squirrels Return, So Does the Owl Cam'

I silently discontinued the owl cam' on Saturday, when I noticed that the fox squirrel family that had been living in the nest box had moved out. I was surprised they stayed as long as they did. However, cool weather this evening (Sunday) seems to have motivated them to return to the nest box, so I've fired-up the nest box cam' again. As before, my preferred view is the five-up, but you can choose from several options on the screech owl cam' main page.

Qwicap Turns Three

Qwicap, my pet project for simplifying the development of Java web applications by allowing them to be structured much like conventional applications (for "conventional" think of interactive command-line apps), turned three years old today.

Actually, it's more like 3.4 years, total, but three years since version 1.0 was released. The releases were internal to U.T. Austin until my boss, his boss, and her boss, all agreed to open-sourcing the product. Then there was the matter of figuring-out whether it could be done at all, given that nobody in my department (the IT dept., no less) had ever done it, or knew of policies that would permit it. Ultimately, I found the lawyer at UT System who dealt with these matters, and discovered that, contrary to all expectations, we actually did have a policy that allowed—and even encouraged—open-sourcing. After reading the policy document countless times, and having many conversations with the ever-helpful lawyer, I even managed to figure-out how to apply the policy to my situation. With that done, there was a lot of paper-work to be filled out, months of waiting for a critical signature while I frantically polished the code and wrote documentation (while also doing all of the things they normally pay me to do), the filing of the paper-work, and, then, figuring-out how to use SourceForge to publish the code.

Finally, Qwicap was posted to SourceForge, and I began trying to figure-out how to make people aware of it. After a few anxious days I was overjoyed to see the news item announcing its release on the SourceForge main page. Wow. All those years of work would not live, die and vanish within the confines of The University. It was actually out there.

That news item lasted three days, and the response to it was deafening, in the same sense that silence can be deafening. Ouch. So, there followed efforts to get Qwicap listed on more topic-specific sites. At the recommendation of colleagues, I started-up this blog, much as it goes against my grain (twenty years ago, it would have been a different matter, but that was then). At the recommendation of my boss, I submitted a presentation proposal to the regional Educause conference. And, of course, I kept working on Qwicap.

The work on Qwicap has gone well. There were a number of 1.3 revisions, then work began on 1.4, the biggest update yet. Several test versions have been released, several of my colleagues have contributed improvements to the project (Kevin, Jay, thanks), and work on it is nearing completion. And we've deployed three more major campus web applications that are built on Qwicap, with very positive feedback from the development team that built them. Most of the team members have baselined Qwicap for their upcoming projects. Since Qwicap's goal was to make life better for developers, that has all been music to my ears.

In stark contrast, the work on publicizing Qwicap has failed miserably. The topic-specific sites ignored it. The blog, which lead-out with my "Programmers Hate Programmers" hypothesis, generated some attention, but if anyone actually did any work with Qwicap as a result, I've never heard about it. The regional Educause deadline came and went without a word, but eventually I was informed that they might be inclined to use the presentation as a backup, in case one of the presentations they actually wanted fell-through. Shortly before the deadline, I swallowed hard and agreed to be a backup, but that never happened. (On the plus side, I never had to write that presentation.) When the national conference came along later, I never quite managed to submit the presentation proposal again. 'Should have, of course, meant to, but still felt the bruises. (On the plus side, I still haven't had to write that presentation, let alone present it.)

I keep an eye on the Qwicap web site, and find that it continues to generate some attention, but most of it relates to the example source code for Java number-guess applications (though not the Qwicap version, naturally). I presume that some people find the examples useful as the interactive equivalent of a "Hello, World" program, but I'm also inclined to suspect that it's the answer to some professor's CS 101 assignment. It's not quite the contribution I'd hoped to make with Qwicap.

Well, Hell.

Last time I looked, there were about 100,000 open-source projects on SourceForge, alone. It seems pretty clear that most of them have utterly failed to make an impression in their niches of the industry, so, statistically speaking, it's no big surprise to be in the same situation. On the other hand, more than a few of those projects seem to have skipped the unpleasant "writing the code" phase of project development, so I kind of thought Qwicap had an edge in that respect. Shows you what I know.

Ironically, when I first proposed open-sourcing Qwicap, I'd been concerned that the product might generate enough interest that I'd have a hard time keeping up with it, so I'd warned my bosses that it might take time away from my usual duties, but they were supportive, nonetheless. Thank you, bosses. [Now there's something you don't hear every day.]

That concern wasn't just wishful thinking. In the late '80s and early '90s I built and maintained the "Gatekeeper" anti-virus system for Macintosh. It was freeware, and developed on my own time. It broke new ground in its field, and achieved a significant level of success; postcards from users arrived from all over the world, those being the days before most people had even heard of email, let alone the Internet. The people who could use email had nice things to say, too, but satisfied users are the quiet ones. The ones you hear from the most are the folks who aren't altogether satisfied; they want features added, or bugs fixed. I encouraged the feedback, and especially the bug reports, of course. Can't fix 'em if you don't know about 'em, and every bug is embarrassing. But, if you haven't had this experience, imagine looking at your email every day for years and finding what comes to seem like nothing but problem reports. Many come with kind words about the value of the product, but the praise is ephemeral, while the worries and the bug hunting and the other work grinds on and on, in every spare moment you can find.

And it wasn't even the case that the Gatekeeper system had a lot of actual bugs. But it seemed like there were, because Gatekeeper had to be implemented as a set of complex, runtime patches to the Mac operating system, and my patches had to coexist with a startling variety of other people's patches, and with all of the undocumented idiosyncrasies of an operating system that was "quirky" on a good day. In practice, the problem-space was limitless and the problems often unreproducible, and uncorrectable. Of course, each bug would be reported many times, and with every version of Gatekeeper (and every OS patch, and every OS version) ever released out there running on somebody's computer, somewhere, they never really went away, even if they'd been fixed years before. And I wanted to represent my handiwork well, so, naturally, I tried to respond to everybody.

After enough years of dealing with all that, day in, day out, I couldn't bear to read the email anymore, or open the letters, or read the postcards. It seemed like there was never any good news, but an endless supply of bad news, all of it directed to me personally, and awaiting my reply. It was relentless, and endlessly depressing. All those years of work, and that was what I had to show for it. The many successes—the product did what I set out to do, and more—couldn't compete in my awareness with the cumulative pounding of the bad news. I had to walk away. Some people were annoyed when their mail went unanswered. I wasn't happy about it, either. Some told me they felt betrayed, which hurt, but walking away had become a matter of survival. (And the product was free, after all. What did they want? Blood?)

The burnout was intense. There came a day when I was contacted by a development house that wanted to turn Gatekeeper into a commercial product. On the one hand, I didn't want to deal with it ever again. On the other hand, it felt like it would be a mistake to have gone through so much and not at least look into this possibility, so I met with a local, commercially successful Mac developer in order to talk about what sort of money I could reasonably expect out of commercializing a product like Gatekeeper. He told me that over something on the order of three years, a product of its kind should be worth about a million dollars. It was an impressive number (still is), but even so I couldn't bring myself to go back to that work.

It felt like about ten years before I could find the will to take on another major programming project, another big idea. So, naturally, I worried about whether I'd go through the same thing again trying to support Qwicap. Turns out that it hasn't been much of a problem. What luck.

One of the nastier traps one can step in, I suspect, is to discover the burn of a really great idea. The kind of idea that you can't not work on, no matter what anybody else thinks of it. At that point, the idea has you right where it wants you, and you have to go where it takes you, while paying mightily for the ride. Great things may come of it, they may make it all worthwhile in the end, but there's only room for so many great outcomes in the world, so the odds can't possibly be in your favor. But you go on anyway.

Maybe Qwicap will make a difference outside The University one day. So far, not so good. Oh, well. I'm not done with Qwicap, and it's not done with me.

'More than I'd intended to say, but I assume I'm talking to myself at this point. If not, good luck with your own great ideas. And have a look at Qwicap.

The Screech Owl Nest Box Cam' Temporarily Returns

Temporarily featured on my screech owl nest box cam': A family of fox squirrels. There's mom, and three pups. The pups stay in the nest all of the time at the moment, while mom is out most of the day inhaling the contents of my bird feeder to make enough milk to keep the pups satisfied. The pups appear to suckle in their sleep, so it's surprising she can meet the demand.

The pups were not born in the nest box; Mme. Squirrel moved them to the nest box a few days ago, presumably in response to rain and/or our increasingly cool weather. Past experience suggests that she will rotate the pups among several nest sites, but for the moment they're in my nest box (stop that gnawing!) and therefore observable.

I don't plan on providing daily commentary, or resuming any of my other owl cam'-related work, but you can watch the critters live. My preferred way of watching them is this five-up view. Other viewing options can be found on the nest box cam' main page.

Qwicap 1.4a34

Qwicap 1.4a34 was released this weekend. With four busy months elapsed since the previous release, 1.4a12, it was time to declare something "done" again, because a lot fixes and improvements have accumulated over that time. The development of this version has coincided with the development of our second and third large, Qwicap-based web applications which will be supplying the end-user and administrator interfaces to UT Austin's new identity management system. The same four developer team is responsible for both applications. They're up against the challenge of schedule-constraints, the rapidly evolving, still-under-development code of the identity management system itself, and the fact that none of them had used Qwicap before (well, one had used its XML engine a few years back). So, I've been watching their progress with interest, wondering which aspects of Qwicap would work well for them, and which wouldn't.

So far, with both applications in an advanced state of development, and user testing of the end-user application already complete, the results are encouraging. The team seems uniformly pleased with the experience of working with Qwicap, and they're already planning to use it as the basis of their future projects. Though I visit their office daily to see how things are going, and to take a look at any problems they want a hand with, there have been remarkably few problems. They've found some minor bugs (minor in that there were small, simple fixes), a few more troublesome bugs, and they've needed a few new features. The more troublesome bugs were interesting, because they were the result of the team choosing a flow-control and markup handling strategy that had never occurred to me, and consequently it was a bit surprising to Qwicap, too. What stunned me was that it worked, and worked well in all but a few obscure cases. I had to sit down with the team-lead and walk through the relevant code several times before I even understood why it worked at all.

Qwicap 1.4a4 and 1.3.3 Released

Qwicap 1.4a4 and 1.3.3 have been released. The change history has all the details fit to print, but the main motivation behind the 1.4a4 release was to make available a fix for a race condition during session tear-down that's been in the Qwicap code base more-or-less forever. Originally, its effects were of little importance—mostly some exceptions showing-up in the logs—and it wasn't at all clear how the problems came about. With 1.4's support for dynamically generated downloadables, those effects started to have an actual impact by sometimes preventing access to the downloadables in the final page of the session. Fortunately, that made the nature of the problem more obvious and led to this bug fix.

Another old bug (or inadequately developed feature) was in the Qwicap.goodbye method which is the method that sends an application's final page to the user. The bug was that the method didn't inform Qwicap that the application was shutting-down, so Qwicap did nothing to help the application shutdown. Which was fine, for applications that invoked goodbye and gracefully returned their way back to, and out of, their main method, but those that didn't could inadvertently persist in the delusion that they were still operating normally by calling a variety of Qwicap methods that should have no role in, and could delay, the shutdown of an application (retrieving user input, sending pages to the user, etc.). Now that goodbye informs Qwicap that the application is shutting down, those methods that shouldn't be used during shutdown will throw a QwicapSessionDeathException when invoked, in order to help the application along in its shutdown activities. (By the way, QwicapSessionDeathException now includes a message that states why the session is dead, or dying.)

In addition, some enhancements have been made since 1.4a0, including: the addition of the Qwicap.getFloat method; moving the Downloadable class into the public API; changing all of the XML attribute manipulation methods to accept arbitrary objects as attribute values; and various improvements to the Javadocs. In addition, the Hunt The Wumpus example application has had its game logic further debugged, and it has been extended to support larger maps, upon request. The extra "config" page that allows larger maps to be specified, also provides a long-overdue example of Qwicap features like the high-level form manipulation API, while further illustrating how multi-page applications function.

Qwicap 1.3.3

Qwicap 1.3.3 was created by back-porting the bug fixes and minor enhancements that have accumulated in the 1.4 branch as of version 1.4a4. So, that race condition is gone, Qwicap.goodbye is beefed-up, Qwicap.getFloat exists, XML attribute values can be specified as arbitrary objects, QwicapSessionDeathExceptions are more informative, Qwicap.convertSubmitButtonsToInputs has had its documentation substantially expanded, various Context methods that didn't need to be public have been removed from the public API, the XML tag hierarchy validator includes document names in any exceptions it throws, all subclasses of Markup now include getMutable and getImmutable methods, the Context.getFile and Context.getExistingFile methods have been documented at long last, some useless code has been removed, and the Javadocs have suffered various improvements. Also, its version of Hunt The Wumpus received a bug fix, and therefore sucks less than it traditionally has done.

Which Reminds Me

While trying to implement the large map generator for the Qwicap 1.4a4 version of Hunt The Wumpus, I was frustrated for quite a while by my inability to come up with a simple implementation for the generator. The generator had a conceptually simple job to do, so it seemed the implementation should be simple, too. We all know such things frequently don't work out that way, but it was bugging me all the same. At one point, I considered using a cellular automaton to generate a hexagon-based map, and that sent me off to Wolfram's A New Kind of Science (NKS) pages, which was more convenient than winching down my copy of the book from its shelf and finding a spot for it on my desk. What I stumbled upon in doing so was WolframTones, a site that generates music using Wolfram's one-dimensional cellular automata. I found it very impressive, and a welcome demonstration of Wolfram's NKS ideas in an easily appreciated, real-world application - which is the sort of thing I regretted the absence of in the NKS book.

My only complaint with WolframTones is that it limits its compositions to thirty seconds. Ideally, it'd be possible to generate arbitrarily long compositions. What I wonder about long compositions is this: Will they seem to hold-together as well as the thirty-second ones usually do? Or does one's brain eventually reject a longer composition due to the extended lack of the sort of patterns designed into music by human intelligences? This would probably be more of an issue with some types of music than others; in particular, some flavors of jazz might not be a problem. And if it's not a problem for some types of music, what does that tell us about music, and will this eventually result in, say, a music generator box for use in stores that will continuously compose and play new music to save the stores the cost of playing background music that someone owns? As background music, shortcomings in the compositions would be masked by the lack of attention being paid to them. Which is fine for customers passing through, but what about the staff that has to hear the stuff all day? Will they eventually hunt down and destroy the box to save themselves? Or would it work well enough that it wouldn't drive people nuts, and, in fact, would periodically produce something really catchy? With every composition produced by an automaton chosen randomly from a set of around 4 billion possible automata, and with no direct access to the box to ask it to save its state, one would end-up in the frustrating situation of hearing a great song that no one had ever heard before, and knowing that you'd never, ever hear it again. That might promote some useful contemplation of the transitory nature of life, but I think, for the most part, it would just be a new way of pissing people off. Technology is great for that.