Continuous Deployment

I listened to a podcast recently about a company doing continuous deployment. I was interested because my company does continuous deployment, and not just of a web application, but of a desktop app. From what I can tell, this is still quite rare.

They were asked how frequently they deploy, and they said every two weeks. I was a little surprised.  Obviously it's a long way from yearly releases, but to me, every two weeks is not exactly "continuous".

Part of the issue is that "continuous" often gets mixed up with "automated". For example, continuous build or integration systems are as much about the automation as they are about continuous. But the primary goal is the "continuous" part. The automation is a secondary requirement needed to satisfy the primary goal of continuous.

Of course, "continuous" seldom actually means "continuous". It usually means "frequent". Continuous builds might happen nightly, or might be triggered by commits to version control.

Our continuous deployment means daily, Monday to Thursday nights. We don't deploy Friday in case there are problems and we don't have anyone working on the weekends.

Our big nightmare is that something goes wrong with an update and all of our roughly 500 installations will be down. Of course, we have a big test suite that has to pass, but tests are never perfect. To reduce the risk we deploy to about ten "beta" sites first. Everyone else gets that update two days later. Having ten beta sites down is something we can handle, and they're aware they're beta sites so they're a little more understanding. In practice, we've had very few major problems.

We have a single central version control (similar to Subversion). Anything committed to version control automatically gets deployed. The problem is when we're working on a bigger or riskier change, we can't send it to version control until it's finished. But not committing regularly leads to conflicts and merge issues, and also means we're only tracking the changes with a large granularity and can't revert back to intermediate steps. Plus, version control is the main way we share code. If the changes haven't been sent to version control, it's awkward for other people to get access to them for review or testing. I think the solution would be a distributed version control system like Git or Mercurial where we can have multiple repositories.

I'm looking forward to reading Continuous Delivery although I think the focus is on web applications.

What, Why, How

Say why not what for version control comments, and comments in code. The code itself tells you "what", the useful extra information is "why". Don't say "added a new method", or "changed the xyz method" - that's obvious from the code. Do say, "changes for the xyz feature" or "fixing bug 1023".

Say what not how in names. i.e. interface and variable names. The users shouldn't need to know "how", they just care about "what". You want to be able to change the "how" implementation, without changing the users. Don't call a variable "namesLinkedList", just call it "namesList". It might currently be a linked list, but later you might want to implement it with a different kind of list.

jSuneido Compiler Overhaul

Implementing a language to run on the JVM means deciding how to "map" the features of the language onto the features of the JVM.

When I started writing jSuneido it seemed like the obvious way to compile a Suneido class was as a Java class, so that's the direction I took.

The problem is, Suneido doesn't just have classes, it also has standalone functions (outside any class). So I made these Java classes with a single method.

Suneido also has blocks (closures). So I compiled these as additional methods inside the class currently being compiled.

As I gradually implemented Suneido's features, this approach got more and more complex and ugly. It all worked but I wasn't very happy with it. And it became quite fragile, any modification was likely to break things.

So I decided to overhaul the code and take a different approach - compiling each class method, standalone function, or block as a separate Java class with a single method. I just finished this overhaul.

Of course, the end result is never as simple and clean as you envision when you start. It's definitely better, but there are always awkward corners.

Unfortunately, more and more of the improvements I want to make are running into the limitations of single-pass compiling, an approach I carried over from cSuneido. I have a feeling that sooner or later I am going to have to bite the bullet and switch to compiling to an abstract syntax tree (AST) first, and then generate JVM byte code from it. That will open the way for a lot of other optimizations.

Java + Guava + Windows = Glitches

Some of my jSuneido tests started failing, some of them intermittently, but only on Windows. There were two problems, both related to deleting files.

The first was that deleting a directory in the tear down was failing every time. The test created the directory so I figured it probably wasn't permissions. I could delete the directory from Windows without any problems. The test ran fine in cSuneido.

I copied the Guava methods I was calling into my own class and added debugging. I tracked the problem down to Guava's Files.deleteDirectoryContents which is called by Files.deleteRecursively. It has the following:

// Symbolic links will have different canonical and absolute paths
if (!directory.getCanonicalPath().equals(directory.getAbsolutePath())) {
    return;
}

The problem was that getCanonicalPath and getAbsolutePath were returning slightly different values, even though there was no symbolic link involved - one had "jsuneido" and the other had "jSuneido". So the directory contents wasn't deleted so the directory delete failed. From the Windows Explorer and from the command line it was only "jsuneido". I even renamed the directed and renamed it back. I don't know where the upper case version was coming from. It could have been named that way sometime in the past. I suspect the glitch may come from remnants of the old short and long filename handling in Windows, perhaps in combination with the way Java implements these methods on Windows.

I ended up leaving the code copied into my own class with the problem lines removed. Not an ideal solution but I'm not sure what else to do.

My other thought at looking at this Guava code was that if that test was extracted into a separate method called something like isSymbolicLink, then the code would be clearer and they wouldn't need the comment. And that might make it slightly more likely that someone would try to come up with a better implementation.

The other problem was that new RandomAccessFile was failing intermittently when it followed file.delete. My guess is that Windows does some of the file deletion asynchronously and it doesn't always finish in time so the file creation fails because the file exists. The workaround was to do file.createNewFile before new RandomAccessFile. I'm not sure why this solves the problem, you'd think file.createNewFile would have the same problem. Maybe it calls some Windows API function that waits for pending deletes to finish. Again, not an ideal fix, but the best I could come up with.

Neither of these problems showed up on OS X. For the most part Java's write-once-run-anywhere has held true but there are always leaky abstractions.

Using ProGuard on jSuneido

ProGuard is a free Java class file shrinker, optimizer, obfuscator, and preverifier.

I'd seen a few mentions of ProGuard and then when I was updating to the latest version of the Guava library I saw that they were recommending it. So I decided to try using it on jSuneido.

It shrunk the size of the jSuneido jar from 2.5 mb to 1.4 mb.  That's pretty good for an hour or two of setup.

I haven't tried the optimization yet, partly because the Guava instructions disabled it. I'm not sure why.

ProGuard also does preverification which should improve startup time, although that's not a big issue for the server usage that jSuneido is aimed at.

It took some trial and error to get a configuration file that worked. I'm not sure it's optimal yet. I still get some warnings from Guava (mentioned in their instructions) and from jUnit, but they don't appear to cause any problems.

Eclipse += Mercurial

It wasn't quite as easy as I would have liked to get the MercurialEclipse plugin working, but it certainly could have been worse.

It was easy to install the Eclipse plugin using the update site: http://cbes.javaforge.com/update

But when I tried to import my project from Mercurial I got a bunch of errors about passwords.

I found a post from someone with the same problem, with a pointer to instructions on how to solve it.

I guess the simple username + password doesn't work with MercurialEclipse, at least on OS X. Sigh.

The answer is to use an SSH key, which I'd avoided till now, but it turned out to be straightforward with the help of the SourceForge instructions. It sounds like it might be a bit trickier on my Windows box - I haven't tried that yet.

I tweaked a few things for the new setup, committed those changes, and pushed the changes to the SourceForge repository. Seems like I'm good to go :-)

The Revenge of the Intuitive

Interesting article by Brian Eno on the user experience problem of too many options, a problem we struggle with all the time with our software. The challenge is that it is the users themselves that keep asking for more options, despite the fact that it ends up making the software harder to use.

Wired 7.01: The Revenge of the Intuitive

Moving jSuneido from Subversion to Mercurial

I've been planning on moving from Subversion to a distributed version control system for a while. Initially I assumed it would be Git since that's what I heard the most about. But I recently listened to a podcast with Eric Sink where he said Mercurial had better Windows support and was simpler to use, especially for Subversion users. An article on InfoQ confirmed this. And Google code has Subversion and Mercurial but not Git. And Joel Spolsky and Fog Creek had picked Mercurial. Joel even wrote a tutorial for Mercurial. So I decided to give Mercurial a try.

When explaining distributed version control a lot of people start by saying there's no central repository, it's peer to peer. This throws off a lot of people because they want a central repository. It's the explanation that's wrong. You can have a central repository, and most people do. The difference is that it's a matter of convention, it's not dictated by the software. And you can also have multiple repositories.

For me, the advantages would be having the complete history locally, even when I'm off-line, and being able to easily branch and merge locally.

Here are the steps I used to convert jSuneido from Subversion to Mercurial. (I haven't converted C Suneido yet, but that shouldn't be too hard, just more history so it'll be slower.)

Download and install Mercurial on OS X from mercurial.selenic.com

Convert the existing SourceForge Subversion repository to a local Mercurial repository:

hg convert http://suneido.svn.sourceforge.net/svnroot/suneido/jsuneido

Ideally you wouldn't convert directly across the network. Instead you'd clone your Subversion repository to your local machine and convert from there. That's primarily so if you have to tweak your conversion and re-run it, you're not dealing with the network delays multiple times.

I was lucky since my Subversion history did not have anything tricky like branches to deal with. And cloning the Subversion repository looked painful. I figured I could probably get away with doing the convert directly. It ended up taking a couple of hours to run.

One nice thing about convert is that you can run it again to pick up incremental changes. (I had to do this once because I had forgotten to send my latest change to Subversion.)

To check out the result I copied the repository to Windows (under Parallels) and installed TortoiseHg. The repository looked reasonable. (A little roundabout, but I wanted TortoiseHg anyway.) TortoiseHg seems to work well.

Enable Mercurial for the Suneido SourceForge project. Add a second repository for jsuneido. See sourceforge.net/apps/trac/sourceforge/wiki/Mercurial

Push the local Mercurial repository to SourceForge.

hg push ssh://amckinlay@suneido.hg.sourceforge.net/hgroot/suneido/jsuneido

I could have also done this with TortoiseHg (but don't look for a "Push" menu option, it's under Synchronize)

I can now browse the repository on SourceForge.

I found the series of three blog posts starting with From Subversion to Mercurial. Part 1, Setting the Stage quite helpful.

Next I have to figure out the Eclipse plugin for Mercurial. I hope it's less hassle than the Subversion one!

Stylebot

Changing the Look of the Web with Stylebot - Google Open Source Blog

A very nice Chrome extension that lets you easily create custom stylesheets for web sites. For example, I often want a different text size for a given site, or to hide certain annoying elements (e.g. ads!)

This is a good example of how Chrome seems to be pulling ahead in the browser competition.

Balsamiq Mockups

I've heard several people say good things about Balsamiq Mockups. I haven't used it myself but I'm planning to give it a try. I like how it produces something that looks like a sketch so people don't get the mistaken idea that it's a finished design.

What Can't the iPad Do?

The girl next to me on the bus had an iPad, so I asked her how she liked it. I expected the usual "it's great", but instead I got "I don't" I asked her why and she said there was too much stuff it couldn't do. I didn't get a chance to dig deeper.

Someone else I know bought an iPad and immediately got someone to jailbreak it for them. Why? Because there's too much stuff it can't do otherwise. When I asked for examples they couldn't really give me any. This is a non-technical person, it's not that they wanted to do anything special.

Obviously, there are things that an iPad is not ideal for. And there are things that an iPad can't do. But there are a huge number of apps and for most people, I just can't see what it "can't" do. All most people do is email and Internet anyway.

It can't run big programs like Photoshop, but most people don't need that. You can't run Microsoft Office, but you can get word processing and spreadsheets.

The touchscreen keyboard is not great for typing a lot, but most people don't type a lot. And if you really need it you can use a Bluetooth keyboard. Most people are happy typing on their cellphone! (I manage to type quite long blog posts only iPhone.)

I would guess one of the reasons for this idea is that people get overinflated expectations from all the hype. And when it doesn't (can't) live up to them, they have to blame it on something.

Which is where the critics come in. People don't remember the specific criticisms like the lack of multi-tasking or cameras or memory cards. All they remember is that "there's stuff it can't do".

And there's always the most common reason people say you can't do something - simply because they don't know how to do it. We get that all the time with our software. You ask people how they like the software and they say it's ok but they really wish it could do xyz. Half the time it already can, they just didn't know it.

iPhone Undo/Redo

I've was getting ready to write a blog post asking why the iPhone doesn't have undo/redo. Selecting text is tricky and it's easy to delete more than you wanted and then have no way to get it back. But when I did a quick search before writing the post, I found it does have it!

If you shake your iPhone you get an undo/redo popup. It appears you can even undo multiple steps, at least in the Notes app.

I'm surprised I didn't run across some mention of this before now. I'm not surprised I didn't discover it on my own. I don't tend to stop and shake my phone in the middle of typing! Maybe the idea is that you get so frustrated you shake your phone?

Honestly, I think this is poor design. First, it's not discoverable. And when people, even experienced ones, don't discover a feature they're probably going to assume it doesn't exist. Second, when I'm typing I generally hold the phone steady in my left hand and type with my right. Shaking is not a natural action, it's like having to take your hands off the keyboard.

Wouldn't it make sense to put an undo key on the keyboard? It could be on the secondary punctuation layout. At least then it would be discoverable. You could still keep the shake interface - presumably someone at Apple thinks it's great.

Connecting the Dots

Sometimes I'm a little slow :-( 

One of the talks at the JVM conference was about a JVM for mobile devices. It used a single pass compiler with no intermediate representation. Suneido also does this but there are some issues with it. Suneido takes the obvious approach of generating a push when it encounters an operand, and an operation when it encounters an operator (after processing its operands). This works great with simple expressions like "a + b" which compiles to "push a, push b, add". But it falls down for more complex things, even for "a = b" since you don't want to push the value of "a". I work around these issues but the code is ugly. And worse, a lot of the ugliness is in the parser, even though the issue is really with code generation.

I wasn't happy with it but, consciously or not, I assumed it was essential rather than accidental complexity. So I didn't look hard enough for a better solution. . 

So I was curious to hear more about their approach. The topic only got one bullet point, something like "code generation by abstract interpretation". 

I started thinking about what that meant. I'm pretty sure what they meant is that you only generate code when you encounter an operator. When you encounter an operand like a literal or variable, you push it on a compile time stack, "simulating" execution. Then you can defer generation of code until you know what is needed.

As I thought about this, I realized I knew about this technique, I'd read about it before. But for some reason I never connected it to my code generation issues.

So when I got home from the conferences I spent three days refactoring the code generation in jSuneido. It wasn't quite as straightforward as I imagined (it never is!). The parser code is definitely cleaner but I had to add more code to the code generator than I would have liked. Overall, I think it's better. I broke a lot of tests in the process, but I finally got them all passing again last night. 

Now I can quite easily add a number of optimizations that I've been wanting to do:

- constant folding

- call private methods directly (no method lookup required)

- call built-in global functions/classes directly

However, there are still things I'd like to do that are difficult with a single pass compile. For example, knowing which local variables are read or written by closures. One way to handle this would be to re-compile if the assumptions were wrong, using information from the first try to do it correctly the second time. But that seems ugly. Maybe I need to drop the single pass compile and just generate an AST. 

JVM Languages Summit Day 2

Another good day of talks starting with Doug Lea on parallel recursive decomposition using fork-join. Amazing how much subtle tweaking is require to get good performance.

This led into Joshua Bloch's talk on performance. There is so much complexity in all the layers from CPU to OS to language that performance varies a lot. He showed a simple example of a Java program that gave consistent times on multiple runs within a given JVM, but sometimes when you restarted the JVM it would consistently give quite different results! Cliff Click's theory was that it was caused by non-deterministic behavior of the JIT compiler since it runs concurrently. The behavior is still "correct", it can just settle into different states. The solution? Run tests over multiple (eg. 40) different JVM instances. That's on any given machine, of course you should also test on different CPU's and different numbers of cores. Easy for them to say. 

Neal Gafter talked about Microsoft's LINQ technology - pretty cool, although nothing to do with the JVM. 

Kresten Thorup talked about his Erlang implementation on the JVM using Kilim for coroutines. Erlang is an interesting language, and quite different from Java so it was interesting to see how he implemented it. He actually runs the byte code produced by the existing Erlang compiler. 

I talked to Remi Forax about whether I should use his JSR292 backport in jSuneido. This would let me use the new technology before Java 7 is released (who knows when). Of course, he said I should. But ... it means developing with the "beta" JDK 7 which still has bugs and is not supported by IDE's. And then it requires an extra run-time agent. I'm not sure I want to complicate my life that much!

JVM Languages Summit Day 1

My hotel is "behind" the Sun/Oracle campus so I had to circle around through the endless acres of parking lots to get to the right entrance. But it was pretty easy, and not as far as it looked on the map. I've never had much to do with giant organizations so it's still a little mind boggling when you use an automated kiosk (like the ones at the airport) to get your visitors badge.  


The sessions were a real mixture, from stuff where the nuances were pretty much over my head, to thinly veiled sales pitches with no technical details. It was pretty neat to be in the company of people you're used to thinking of as gurus, like Doug Lea, John Rose, Joshua Bloch, and Cliff Click. And nice to see they have their frustrations with the technology also.


It's naive of me, but unconsciously I expect really smart people to be "rational", and it's always a bit of a disappointment when that proves to be untrue. Smart people have egos, are insecure, or argumentative, or negative, or defensive, or obnoxious, just like everyone else. 


Maybe I'm just too soft, but I felt bad for one guy who basically got told he was doing it wrong. It seems like they could just have well asked "did you consider ..." or "what would you think about ...", rather than just "that's wrong, you should have done ..."


Mostly I just listened to the conversations. In the Java / JVM area I still feel like a relative novice and I'm not sure I have much to contribute yet. But for the most part I didn't feel too much out of my depth, so that's good.

OSCON Wrapup

The last two days of OSCON were good.

I got to hear Rob Pike talk about the Go language. Rob is a legend in software and Go is a cool language. In some ways Go is more like C or C++ in that it's compiled to machine code with no VM. But unlike C++ it compiles extremely fast. For what he called a party trick he showed it compiling every time he typed a character - and it kept up. It has features I miss in Java like pointers (but safe) and values on the stack (not always allocated). It also has "goroutines" - lightweight threads like coroutines. But its attractions aren't quite sufficient to tempt me away from Java. They don't even have a Windows version yet, let alone all the support libraries and frameworks that Java has.

I also got to hear another legend, Walter Bright, talk about his D language. I used Walter's C and C++ compilers for many years. D also has some very interesting features. Andrei Alexandrescu of Modern C++ Design fame is now working on D and has written The D Programming Language book.

One feature D has that is sorely missing from other languages is the ability to declare functions as "pure" (ie. no side effects) and have the compiler verify it. This (not lambdas) is the key to functional programming. And yet languages like Scala that claim to support functional programming don't have this.

I also went to a talk by Tim Bray whose blog I read. He was working at Sun but moved to Google after the Oracle buyout. His talk was on concurrency. He was very pro Erlang and Clojure but didn't mention Scala. When asked about it he said he thought the Scala language was too big. It does have a sophisticated type system, but the actual syntax is quite simple - smaller than Java. Scala's Actor implementation has been criticized but it's been improved in 2.8 and there are alternatives like Akka.

OSCON Another Day

After the less than thrilling key notes, I went to another Scala session. A lot of it was repetition, but I learn a bit more at each one. The recurring theme seems to be if you're going to use Scala, use Simple Build Tool (SBT).

Next I went to a talk on GPARS, a Groovy concurrency library. The talk was as much about concurrent programming patterns as about Groovy, which suited me.

Next, I was going to go to one of the database talks, but then I realized it was a vendor presentation and they're usually more sales spiel than technical. Looking for an alternative I noticed Robert (R0ml) Lefkowitz had a talk on Competition versus Collaboration. If you've never listened to one of his talks, it's well worth it. They are as much performances as presentations and always thought provoking. (search for Lefkowitz on the Conversations Network)

Next was a talk on Clojure (a Lisp that runs on the JVM). The title was "Practical Clojure Programming" which sounds like an intro, but it was actually about build tools, IDE's, and deployment. Like most of the audience, I would have rather heard more about Clojure itself. I guess we should have read the description closer.

Finally, I snuck into the Emerging Languages Camp to hear Charles Nutter talk about Myrah (formerly Duby) his close-to-the-JVM-but-like-Ruby language. I would have been tempted to go to the Emerging Languages Camp (it was even free) but by the time they announced it, I'd already signed up for the regular sessions.

All in all, a pretty good day. Lots of food for thought, which is, of course, the point.

One thing I forgot to mention yesterday is that a lot of the Scala people are also (or ex-) Ruby/Rails people.  Maybe that's simply because they're the kind of people that like to learn/adopt new things.

But a lot of people left Java and went to Ruby, so it's surprising to see them coming almost full circle back to Scala. Scala is better than Java, but it's still a statically typed language like Java, which is part of what people seemed to reject. Maybe Ruby wasn't the silver bullet they were hoping. Maybe it was performance issues. Maybe they realized that static typing does have advantages after all. Maybe they realized the advantages of running on the JVM (although jRuby allows that). Maybe Scala's improvements over Java are enough to win people back.

OSCON Part One - Scala

I just finished the first day and a half of OSCON - in the Scala Summit. And contrary to my anti-social nature, I even went to a Scala meetup last night.

As I've written before, I'm quite intrigued with the Scala programming language. It runs on the JVM and interfaces well with Java. It combines functional and object-oriented programming. It has actors for concurrency. And it has a rich type system that is probably Turing complete, like C++ templates. 

Scala seems to be attracting a lot of attention. Of course, the Scala Summit attendees are all keen, but there were also several other language developers (like Charles Nutter of jRuby) interested in borrowing ideas from Scala.

Programming in Java is like driving a truck. It's not fast or fuel efficient or fun to drive or comfortable. But it gets the job done without a lot of problems and it can haul just about anything. 

Why do people like to drive a fast car? It's not like they regularly need go from 0 to 60 in 5 seconds, or hit 200 km/hr. But they like to know that if they "need" to, they could.

Similarly, I think people like to know their language "has a lot of power under the hood", even if they never use it. And it gives lots of potential for books and conference talks that keep people excited.

And like you could use C++ simply as a better C, you can use Scala as a better Java. This lets less sophisticated users get involved as well. 

The funny part is that it's very reminiscent of C++.  There were all kinds of talks and articles and books about all the cool stuff you could do with templates and other fancy C++ features. Now, all you hear are negative comments about C++, too complicated, too hard to use, etc. I start to think I'm the only person that liked C++. 

But there are differences too. Scala didn't try to be backwards compatible with Java the way C++ was backwards compatible with C. And Java already had object-oriented programming, so Scala isn't as big a jump as C++ (in that respect). 

If nothing else, it's made me really want to spend some more time with Scala. It will sound crazy, but I'm very tempted to rewrite jSuneido in Scala. Thankfully, that's something that could be done gradually. I think it would let me make the code much smaller and cleaner. I think it would also make it easier to switch back and forth with Suneido coding, since Scala has things like named and default arguments, optional semicolons, and type inference that make the code much more similar to Suneido code.

Time Capsules

I use an Apple Time Capsule for my home wireless router and backup storage.

Time Capsules have a bad reputation for dying and I've had mine for quite a few years so I was a little nervous about it. If it died I wouldn't have a backup of my iMac. Which would be ok unless it happened to die at the same time. This seems unlikely, but it's surprising how often you do get simultaneous failures. For example, a power surge due to lightning. I can also keep the external drive at work so I have an offsite backup in case the house burns down.

I had a 500gb external drive that I'd used for backups, but it's not big enough to do a complete backup of my 1tb iMac. So I went and bought a Lacie 2tb external drive and used SuperDuper to make a backup. I used the free version, but I'll probably get the paid version so I can update the backup without redoing it.

Then I decided I should also backup my MacBook and my MacMini. I didn't have much critical stuff on them, but a backup would save hassle if I needed to restore. But SuperDuper takes over the whole drive so how could I backup additional machines? The answer seemed to be to partition the drive, but I didn't want to have to redo my iMac backup (600gb takes a while to backup, even with Firewire 800). I searched on the web and found various complicated ways to resize partitions. Finally, I found that with recent OS X you can resize right from the Disk Utility. All the complicated instructions were for older versions of OS X.

The "funny" part of this story is that a few days later I went to use wireless and it wasn't working. I went and checked on the Time Capsule and it was turned off. Strange, because I leave it running all the time. I turned it on and about 10 seconds later it turned itself back off.

My computer was still fine, so I didn't actually need the external backup, but I was glad to have it nonetheless.

I phoned the local Apple dealer (Neural Net). The receptionist wanted me to bring it in and they would look at it in the next few days. I didn't want to be without internet for days so she let me speak to the technician. When I described the symptoms he said the power supply had died. But Apple doesn't let them repair them and doesn't supply any parts. Apple has been promoting their environmentally friendly products, but no matter how they're built, a non-repairable "disposable" product isn't very environmentally friendly.

I would have preferred to give Neural Net the business but they didn't have any Time Capsules in stock so I picked up a 2tb Time Capsule from Future Shop. 10 minutes after opening the box I was back up and running. (Although the initial Time Machine backups took considerably longer.)

One nice thing is that Time Machine backups seem to be a lot less intrusive. Before, when Time Machine kicked in it would really bog down my machine. If I was trying to work I'd often stop it. But now I don't even notice when it runs. I'm not sure how a new external device would change the load on my computer, but it's nice anyway.

My old Time Capsule ran quite hot, even when it wasn't doing anything. I was hoping the new ones would be better, but it seems much the same. I haven't measured it, but I assume heat means power consumption. I'm not sure why it can't go into a low power mode when it's not active. The other reason they run hot is that they have no ventilation or heat sink. Apparently there is an internal fan but all it does is stir the air around inside a small sealed box. You'd think they could come up with some better heat management without compromising their design. I would guess the heat is one of the big reasons they have a reputation for dying. Electronic components tend to have a shorter life at higher temperatures.

Rather than throwing out the old Time Capsule, I passed it on to one of the guys at work that tinkers with hardware. I thought he could at least extract the 1tb drive. But he managed to repair the power supply and is using the whole unit. I guess the hardest part was getting the case open! I'm glad it was saved from the landfill for a while longer.

Now that I have a bigger drive I thought I might as well backup Shelley's Windows machine as well. I have it set up with Mozy for on-line backups but just with the free 2gb account so I'm only backing up selected things. I'd seen Mozy will now backup to external drives so I thought I'd set this up. Unfortunately, it only backs up to directly attached drives (i.e. internal or USB) not to network drives. I'm not sure what the logic is behind that choice. I could use different software, but I think what I'll do (I haven't got round to it yet) is to use the old 500gb external drive.

iPhone Multi-tasking

A lot of people made a big thing about how the iPhone didn't have multi-tasking. But personally, I never saw any of the reasons as very compelling. Given limited cpu power and memory and a tiny screen, it made perfect sense to single task.

Sure, there are probably a few reasonable uses of multi-tasking. But there are way more potential abuses.

I look at my Windows machine, which is continually thrashing away when I'm not doing anything. Every piece of software I install wants to run stuff in the background. Just to check for updates once a week they want to have a process running constantly. That's not a benefit, that's abuse.

Two days after I installed iOS 4 with its long awaited multi-tasking, I went to use my iPhone in the morning and the battery was totally dead - it wouldn't even turn on. It had plenty of power the evening before. I can't be 100% sure of the culprit, but I assume it must have been some application left running by the new multi-tasking. I suspect it was a mapping app that I'd been playing with, probably running the GPS constantly or something like that.

On the other hand, according to Apple, most apps do not actually run in the background, they just get suspended and resumed. If that's really true in all cases, then I'm not sure what drained my battery overnight.

So now I find myself regularly "killing" all the active apps because I'm paranoid about this kind of scenario. Great, a "feature" has imposed a large manual overhead on me.

Hopefully the situation will improve once apps are updated to work better with the multi-tasking. But there will always be poorly behaving apps.

What I find strange is that Apple went from not allowing multi-tasking, to making it the default, with no way to switch it off. It seems like an option that you had to explicitly turn on (or at least some way to disable it) would have still silenced the critics, but wouldn't have imposed the cost on those of us that didn't want it.