The death of HyperCard, a whodunit

Stanislav Datskovskiy posts his theory on the murder of HyperCard. It wasn't the butler.

Baker's Treadmill and Disruptor

Flying Frog Consultancy in Cambridge, England posts a nice comparison between Disruptor and low-latency GC algorithms:

The core of [Disruptor's] idea is to accomplish all of this message passing using a single shared data structure, the disruptor, rather than using several separate concurrent queues.

Baker's Treadmill is a low-latency garbage collection algorithm. Allocated blocks in the heap are linked together to form a cyclic doubly-linked list that is divided into four segments using four iterators that chase each other around the ring as heap blocks are allocated, traced and freed.

Cleverly observed with a good diagram. As they say, read the whole thing.

Microbenchmarking and JVM magic

Martin Thompson posts on what I call microbenchmarking and JVM magic, Biased Locking, OSR, and Benchmarking Fun. It is a good praticum to Cliff Click's What the heck is OSR and why is it Bad (or Good)?. OSR is the kind of JVM magic that both surprises and frightens, but makes perfect sense. I walked a colleague through OSR and he agreed with a shrug: the thing you are glad someone else wrote, excess hair.

Colebourne on Scala: EJB2 redux?

Stephen Colebourne posts a lengthy critique of Scala, Scala feels like EJB2. Scala attracts my inner physicist but brings concern to my practical programmer. Colebourne makes these implicit thoughts explicit.

Defeating SSL certificate validation in Java

This post is a hack. You have been warned.

My employer swaps out SSL certificates traversing the corporate firewall. It is a financial firm with regulatory responsibilities that require monitoring all traffic leaving the company, including encrypted traffic.

One side effect is trouble with well-meaning programs which validate SSL certificates before trusting an encrypted connection. These validations fail using the self-signed replacement certificate.

Maven is such a tool:

[WARNING] Could not transfer metadata com.devspan.vendor.envjs:envjs-rhino/maven-metadata.xml from/to sonatype-oss (https://oss.sonatype.org/content/groups/public): Error transferring file: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

The remark about "PKIX path building failed" is characteristic of the probelm.

There is lots of good advice on fixing this correctly, say, here, here or here. But none of them work just now; I cannot edit the locked-down trust store for Java, it does not already contain the aforementioned replacement certificate, and I do not want to build a custom Maven to work around the problem.

Enter the hack.

$ mvn -Djavax.net.ssl.trustStore=/dev/null package

Martin Thompson on lock cost

Anything Martin Thompson says about performance is usually worth a good study. No exception is Locks & Condition Variables - Latency Impact.

His takeaway points:

1. The one-way latency to signal a change is pretty much the same as what is considered current state of the art for network hops between nodes via a switch.
2. The impact is clear when letting the OS choose what CPUs the threads get scheduled on rather than pinning them manually.

Azul's approach for low-latency Java servers

I no longer work in the low-latency space. Still Azul's completion of a non-VM "pause-less" JVM for Linux is exciting. (Also running a JVM on a VM was too recursive.) May it be a benefit to those who need low-latency java servers.

Whither JDK8?

Stephen Colebourne posts on the future of JDK8 based on current JEPs. Among the possiblities, I'm looking forward to:

• Getting the PID of the current process
• Multi-style collections
• Reflection for parameter names
• Significant help for annotation writers (the compiler model stinks for usability)

Punk rock languages

I love Chris Adamson's description of Punk Rock Languages. His introduction should get your blood flowing:

That C has won the end-user practicality battle is obvious to everyone except developers.

The year is 1978, and the first wave of punk rock is reaching its nihilistic peak with infamous U.K. band the Sex Pistols touring the United States and promptly breaking up by the time they reach the West Coast. Elsewhere, Brian Kernighan and Dennis Ritchie are putting the finishing touches on their book The C Programming Language, which will become the de facto standardization of the language for years. While totally unrelated, these two events share a common bond: the ethos of both punk rock and C have lasted for decades, longer than anyone in 1978 could possibly have imagined.

And in many important ways, C is the programmer’s punk rock: it’s fast, messy, dangerous, and perfectly willing to kick your ass, but it’s also an ideal antidote to the pretensions and vanities that plague so many new programming languages. In an era of virtual machines and managed environments, C is the original Punk Rock Language.

Peregrine: Help for programming concurrency

Good news from Columbia University. Peregrine is automated software to aid in programming concurrency. More in the ACM: Major Breakthrough Improves Software Reliability and Security:

"Our main finding in developing Peregrine is that we can make threads deterministic in an efficient and stable way: Peregrine can compute a plan for allowing when and where a thread can 'change lanes' and can then place barriers between the lanes, allowing threads to change lanes only at fixed locations, following a fixed order," says Columbia professor Junfeng Yang. "Once Peregrine computes a good plan without collisions for one group of threads, it can reuse the plan on subsequent groups to avoid the cost of computing a new plan for each new group."

Herb Sutter: Elements of Modern C++ Style

The always readable Herb Sutter begins Elements of Modern C++ Style with:

The C++11 standard offers many useful new features. This page focuses specifically and only on those features that make C++11 really feel like a new language compared to C++98, because:

• They change the styles and idioms you’ll use when writing C++ code, often including the way you’ll design C++ libraries. For example, you’ll see more smart pointer parameters and return values, and functions that return big objects by value.
• They will be used so pervasively that you’ll probably see them in most code examples. For example, virtually every five-line modern C++ code example will say “auto” somewhere.

Use the other great C++11 features too. But get used to these ones first, because these are the pervasive ones that show why C++11 code is clean, safe, and fast – just as clean and safe as code written in any other modern mainstream language, and with C++’s traditional to-the-metal performance as strong as ever.

This sounds good.

Focus, focus, focus

Steve Jobs, role-model for Google CEO.

The 300

A collation of the top 300 algorithms. Please contribute implementations.

Why does blogger republish my posts so often?

Watching the ThoughtWorks Alumni aggregator feed, I see my own posts reappear frequently in batches. I'll see posts last edited days ago suddenly repost. Any suggestion on stopping this misbehavior would be appreciated.

Cheers,
--binkley

When it rains, it pours

More on one of my favorite themes: Romain Prieto provides Expressive code: combining Guava, LambdaJ and Hamcrest.

Kotlin and delegation

I have harped on Java for some time to add language support for delegation. Well, Java is not headed that direction anytime soon. But Kotlin delivers!

Saying:

class Derived(b : Base) : Base by b

forwards method calls on "Derived" to "Base" through the instance of Base named "b". Nifty!.

Kotlin is so full of good ideas it's hard to know where to start.

Neal Ford on functional programming

ThoughtWork's Neal Ford posts a great discussion of object-oriented vs. functional style for coupling and composition. Functional is where it's at. Read Neal to see why.

Amazon and SOA

Steve Yegge's rant really describes how to make SOA work at full-on scales. This is pure gold:

[M]onitoring and QA are the same thing. You'd never think so until you try doing a big SOA. But when your service says "oh yes, I'm fine", it may well be the case that the only thing still functioning in the server is the little component that knows how to say "I'm fine, roger roger, over and out" in a cheery droid voice. In order to tell whether the service is actually responding, you have to make individual calls. The problem continues recursively until your monitoring is doing comprehensive semantics checking of your entire range of services and data, at which point it's indistinguishable from automated QA. So they're a continuum.

Memory for nothing and chips for free

As a long time Linux user, this quote from MSDN nearly spilled my coffee (emphasis mine):

Fundamentals such as memory usage represent a key engineering tenet of Windows 8. In building Windows 8 we set out to significantly reduce the overall runtime memory requirements of the core system. This is always good for everyone and especially in a world where people want to run more and more apps at the same time or run on systems with only 1 or 2GB of memory.

I'm happy to read this post and see engineering has a seat at the table for Windows 8. Funny world where memory is next to free.

If you say "world's best", you should be right

Peteris Krumins publishes the World's best introduction to sed. And he's right.

The power of laziness

On the power of laziness from Australian CIO Magazine:

'Progress isn't made by early risers. It's made by lazy men trying to find easier ways to do something.' Robert Heinlein (1907-1988)

And Seth lived a hundred and five years, and begat Enos

Well, Java has not been around 105 years, but it feels like that sometimes.

David Polak explains why Scala is too hard to replace Java. I laughed at this true description of JEE programming:

Junior developers who are asked to maintain code written by senior developers have to understand the idioms and patterns in the code. While Scala makes putting business logic at the forefront of the code (rather than distributed through a bunch of for loops and complex if statements), depending on the idioms used, decoding that logic is non-obvious. This is a variant of the lack of idioms issue, but at the end of the day, you need a team with a mind-meld to grok some Scala code. … In Java, the patterns are vomited out of the IDE, so developers grow up being able to spot the patterns. That's not true of Scala where the idioms are diverse and team/framework specific.

How to know if Scala is right for you?

• Your company has speakers at JavaOne, OSCON, Strangle Loop, QCon: Scala will be easy
• Lunch-time discussions involve the criteria for moving from a developer to a senior developer: Scala will be hard
• Your developers can write code in NotePad if they have to: Easy
• Your developers stare blankly or say 3 "Hail Marys" when they hear the name "Zed Shaw": Scala == Hard
• Developers all follow Dean Wampler on Twitter: Scala Easy
• Your developers come in at 9:15 and leave before 6 and don't check work email at night: Hard

Given Dave's solid criteria in the posting, my organization will find Scala hard to adopt. I am saddened, because Scala looks fun, productive and intelligent. But my foremost job is to help my organization succeed.

Which brings me to Kotlin (emphasis in the original):

"Project Kotlin" is the codename for a statically-typed JVM-targeted programming language developed by JetBrains and intended for industrial use.

On the Java to Scala scale Kotlin lies solidly between, more like Java in some areas, more like Scala in others, unlike either in yet others. Overall Kotlin looks like a winner for organizations looking to bail from Java but find Scala and friends daunting.

Kotlin may prove a winner.

Architecture gone wild

Tony Arcieri rants on bad suggestions from Node.js folks. His catch phrase, "It gets worse". I love his conclusion:

Clearly the next logical steps are to store previously computed Fibonacci numbers in MongoDB. Or you could build a system with Socket.IO which caches previously computed Fibonacci numbers client-side using a distributed hash table. Then you'd be well on your way to a multimillion dollar cloud-based Fibonacci number service. Eventually you'll probably want to build in an OpenMP C++ native extension to calculate Fibonacci numbers across multiple CPU cores. That way you'll have a truly roflscale Fibonacci web service.

I run into this kind of thinking occassionally at work, but it is quickly tamped down before real money gets burned.

OCaml in real life

Yaron Minsky of the quant prop shop, Jane Street, promotes OCaml in the ACM Queue with OCaml for the Masses. His writing is exact, his code example illuminating and short.