Recap of the Schneide Dev Brunch 2016-12-11

brunch64-borderedYesterday at sunday, we held another Schneide Dev Brunch, a regular brunch on the second sunday of every other (even) month, only that all attendees want to talk about software development and various other topics. This brunch was a little smaller in numbers of attendents, but very interesting nonetheless. As usual, the main theme was that if you bring a software-related topic along with your food, everyone has something to share. Because we were very invested in our topics, we established an agenda for the event. As usual, a lot of topics and chatter were exchanged. This recapitulation tries to highlight the main topics of the brunch, but cannot reiterate everything that was spoken. If you were there, you probably find this list inconclusive:

Household roboters

We started our brunch talk by mentioning the services our five years old roombas provide for us, especially keeping the floor free of any small things. The biggest effect when having an electronic pet like a roomba is that you learn to keep your things above ground, especially cords with expensive electronics on the other end. The continuous elimination of dust is just a positive bonus on top of your behaviour adjustment. You keep the floor tidy, the roomba just mercilessly enforces this rule.

Today, there are many alternatives to the original roomba and most have really nice features and abilities. So no matter what brand you buy, you’ll get a capable floor police.

Code Review priorities

In our recent dev brunches, we talked about code review tools and code review habits. This time, we talked about code review priorities and the sorry state we are still in with current tools. We worked out that its nearly useless to only show the diff with a few lines of surrounding code and expect a thorough review. Even the concept of “changed files” is rather distracting in an object-oriented language. But even the current tools are only as good as we make use of them.

The first priority of code reviews should be finding and eliminating bugs – “real” bugs that would have had surfaced in production otherwise and “hypothetical” bugs that could have shown up in production. This means that code review is in its core an activity for the user of the software. Only second priority is the understandibility of the source code. If the reviewer doesn’t understand the code, chances are high that nobody will, including the author in a few weeks or months. Cleaning up the code now mitigates the problem for the lowest possible cost because the “hurdle of understanding” isn’t raised yet. A code review should never work on the level of linters and should not address topics that can be checked by an automatic tool. Suggestions about refactorings should be kept to a minimum because they may serve no purpose if the code isn’t touched again. Refactor when the code is opened for the second edit, not on the first review. Review the code on the semantic level, not on the syntactic.

And keep in mind that code review tend to be used for conditioning remarks (“don’t do that”, “this is ugly”, “I don’t approve”, etc.). Try to avoid conditioning and strive to provide educational comments (“if you change this to that, then you’ll profit from this benefit”, “here’s a suggestion for a better approach and here’s why it is better”, etc.). But we also discussed that at this point, the code review remarks are probably better said in a pair programming session.

Code reviews are a powerful tool for development teams, but with power comes danger. Hopefully, we get adequate software tools to help us avoid the common traps soon.

Time management

Out of interest, we talked about some principles and practices to better manage one’s time.

The first thing to be aware of are the two fundamentally different schedules of management and development. The manager’s schedule is clocked in 30 minute intervals and driven by outside demand (meaning that a manager idles when not requested), while the maker’s schedule works with 4-hour blocks of uninterrupted, deeply concentrated work. You can probably see the problems that arise when somebody in a maker cycle is interrupted multiple times as if he was in a manager cycle. The first thing you can do is to announce your maker cycles (by clear “busy right now” indicators like headphones or a “do not disturb” sign) or announce your manager cycles much to the effect of consultation hours. Let your disturber know if he can disturb safely or if even the question causes damage.

Another important thing is to arrange your surrounding according to your schedule. Your schedule is so important that you should choose your service providers according to it. For example, if you work full time, look for hairdressers that work saturdays or dentists that offer appointments in the night. If you need to contact people for personal matters during work hours, allocate a specific timebox each day or at one day in the week and do it then. Announce this timebox to everybody who might want to contact you during work. This way, to can differentiate people that respect your (announced!) schedule and people that don’t. Depending on your rigorousness, you can cut the people that harm your schedule out of your life.

Work only with people who value your expectations (if reasonable). If you give a task to somebody, let’s say a craftsman, and state the deadline, you need to be sure the deadline is met without you checking or the craftsman will report back in time. Don’t give tasks to people who leave you in the lurch.

It all boils down to keep the control about your calendar. Whenever you give somebody else the opportunity to “conquer” a slice of your available time at their convenience, you increase your own inconvenience.

Karlsruhe C++ User Group

The year 2017 started with a new-founded C++ user group in karlsruhe that started with great events. David, the organisator of the user group is a regular attendee at our Dev Brunch and reported about his experiences with the boot process of the user group. He found a sponsor in the Clausmark GmbH and accompanied the monthly talks and programming events with a regular table that provides a similar format as our Dev Brunch, just in the night and not in the morning. We also talked about possible future content, and found code-centric “git guided live casts” a worthwhile format. Another format, the excellent code retreats are a great way to learn from others, but require a full day and not just two hours in the evening. The Game of Life kata is really fun, even when done repeatedly. Once you discover the solution in APL, you’ll want a special APL keyboard, too.

We are looking forward to hear great talks and meet cool people at the C++ user group Karlsruhe.

Sales knowledge

Our last topic in the bonus time (we were lenient with our scheduled time box, it’s sunday!) was about sales and the installation of sales knowledge and sales behaviour in a group of developers. We agreed that starting with Strategic Selling is a good choice because the process/framework is compatible with established developer culture and effective in its results. The resulting shift in the perception of occurrences is immediate and powerful. Strategic Selling is a rather old sales process that share some similarities with Solution Selling, another nerd-friendly process for complex business-to-business (B2B) sales.


As usual, the Dev Brunch contained a lot more chatter and talk than listed here. The number of attendees makes for an unique experience every time. We are looking forward to the next Dev Brunch at the Softwareschneiderei in April. We even have some topics already on the agenda (like a report about first-hand experiences with the programming language Rust and a discussion about the concept of provisioning). And as always, we are open for guests and future regulars. Just drop us a notice and we’ll invite you over next time.

The Four Steps of Complex Tasks (Part II)

In the first part of this blog entry, we talked about how complex tasks need to be addressed with a proper problem-solving framework. One such mental framework can be found in traditional warfare. It involves all the anticipated artifacts like headquarters, mission statements and a general’s map, but will likely omit the gruesome parts of actual battle.

We started with the mission statement and then began to make a plan with four steps:

  • Reconnaissance
  • Maneuver
  • Offensive
  • Defensive

Step one: Reconnaissance

In the first step, we tried to unveil every part of the scenario and draw a complete map of the terrain. A botched reconnaissance is probably the root cause of most failed missions. You can read all the details about the reconnaissance step in the first part of this blog entry.

Step two: Maneuver

Emergency preparation equipment on the grass, on the nature backgroundFor a real army, maneuvering means to “change position”. In preparation of a battle, it means to secure the positions that will maximize the own effect and/or minimize the effect of the opponent. Most battles are already decided in this phase, with the following fighting being more or less the playback of the drama the generals anticipated. The ultimate victory in military warfare is the victory by maneuver, when the opponent revises his position before the battle and concedes that he lost already.

In our example case, we wage war on the call for proposals for a big software project. It would be our ultimate victory if we could convince the project owner that no call for proposals is even necessary because we are clearly the best-fitting proposer. But that would have required actions from our side in the past and that chance has passed. We need to prepare for the “fight” under the rules of the project owner, we need to submit a better proposal than everybody else.

Our maneuver step contains every preparative action we need to do so we can play out the last two steps in a smooth fashion. If we need to create an account to submit our proposal, then now is the time to create it. If we need to buy some office supplies to print the proposal in top-notch quality, we should buy them now. Just like a real army stocks their supplies near the anticipated battlefield, we need to stock our supplies, physical like the office supplies or virtual like the user account or a signing certificate.

The goal of maneuvering is to never stall when the last two steps are due. We take our knowledge from the reconnaissance step and interpolate it into the future. The maneuver actions support our scenario of the future. Once the third step is in progress, every negligence in maneuvering will mean delay, makeshift solutions and partial failure. If the negligence is too widespread, it will result in overall failure.

Step three: Offensive

Hiker crossing rocky terrain in the Bryce Canyon National Park, USAIn a real battle, once the maneuvering is done, things “get real”. This usually means that shots are fired. In our example, we also fire shots, but imaginative ones. During the offensive, we really work on the meat of the proposal. We dig into the details of the project and produce estimates and concepts. We use the mandated structure for the proposal to fill our proposition in. We concentrate on fabricating content.

In this phase, things get messy and confusing very fast. There are just way too many details needing attention all at once. This is where our plan from the reconnaissance step comes to our rescue. We need to make sure that we don’t stray from the plan too much. Remember, our “opponent” isn’t moving, it’s a static target. So our plan will stay mostly valid during the offensive. If not, this indicates flaws in previous steps and should be taken seriously. If you can afford it, time- or effortwise, rewind your mission back to step one if you find yourself attacking dummy problems or empty terrain that leads you nowhere. A well-planned offensive has immediate and visible effects.

Your work during the offensive phase might look chaotic and erratic from the outside, but it should be cold-blooded and calculated in your experience. This phase is known to intimidate you with overwhelming feelings of anxiety and despair. Stick to your plan and don’t panic! If you’ve planned it well, it will go well. If you didn’t trust your plans beforehands, why would you even proceed to this step? There is no damage done when your reconaissance unveils a task to heavy for your taste and you make an immediate retreat. There is little loss in surrendering your efforts to an opponent that played the maneuvering game better than you, like requiring several comparable projects as reference for the proposal, but you are a newcomer on the market. It will ache, but you cut your losses and move on. But starting an all-out offensive that you are not sure you’ll win? That’s just stupid or desperate.

Two remarks here: First, Being sure you’ll win means you are sure to fulfill your mission, in our example to submit a valid proposal. That doesn’t imply you need to be sure to win the pitch itself. Stick to your mission statement and win the battle before you try to win the whole war. Second, if you hold back on your offensive, you set yourself up for failure because of indecision and foot-dragging. Every offensive should be all-out or not started at all. You are in this game to win, not to play.

Step four: Defensive

Let’s assume our offensive was successful. In a real battle, we have conquered the enemy’s stronghold or additional terrain. The enemy is defeated. A movie would now show the end credits, a computer game the game results. But this is real life, there is no “end point”. Your troops are all over the place, probably in a sorry shape and without a clear goal to look forward to. If your enemy has any troops left, now is the best moment to run you over. Your victory would be pyrrhic, your winning would finally cause your defeat.

The clever strategist has already planned the defense after the offensive (and victory). Often, this means a partial retreat after the battle in order to “straighten the lines”. We can’t do that in our example, it would mean we take back promises after our proposal wins the pitch. But we can plan our defense after victory.

Let’s assume our proposal wins. What does that mean for our company? Who will work on the project? Can we keep our promises even if external circumstances like other projects, other proposals or our staff changes? What will we gain from the project? What concessions can we make to the customer if he wants to re-negociate? Do we need to re-negociate as soon as the agreement is made? The last question answered with yes is a typical sign of over-commitment in the offensive phase and tells about poor leadership.

In our example, let’s say we’ve promised the customer a 24/7 support hotline for the software. We need to make sure how to fulfill this promise before we send out our proposal. There is no value in making hollow promises that we cannot keep. This would be like losing captured terrain again just because you cannot provide enough troops to secure it. It’s not worth the effort and an all-around damper on morale. Just to be clear here: You don’t need to act on the fullfilling of the promises before you’ve won, but you cannot wait with the planning. So we need to have a clear plan on how to implement a 24/7 support hotline, but we only need to act on it as soon as we are sure it is really necessary. We need to take steps one and two for the support hotline mission, but hold back the later steps until our proposal has won and the contracts are signed.

Don’t omit this step in your planning. A successful offensive without the backing of a good defensive is the prelude to a disaster.


We’ve learnt the four steps to master each complex task, lent from the art of warfare, namely reconaissance, maneuver, offensive and defensive, that form a pattern you can repeat each time with the same structure, but always different content. Every task will require a different solution, but the solution’s framework is always the same. This framework can be applied to tasks that seem to have nothing in common with warfare, but still play by the same rules. This is a powerful tool because it opens centuries of knowledge in military warfare to your creative transfer approach. And it is an effective tool because you don’t need to study history to apply it to your cause. Just reiterate the four steps and conquer your task.

If you’ve already applied these four steps, perhaps without consciously realizing it, I would love to hear your story and the outcome. Please leave your comment below!

The Four Steps of Complex Tasks (Part I)

In software development, we often face complex tasks that need to be addressed with nearly certain success rates. “Failure is not an option” is an easy sentence to say, but hard to implement. As experienced software developers, we’ve learnt our share from failures or near-misses and have probably derived an implicit problem-solving framework for our typical tasks. But what if the tasks are not so typical? What if we need to do complex work where we lack experience – and know it?

Adopting a problem-solving framework

In order to keep this blog entry as practical as possible, lets tell the theory with the help of an example that will be foreign to most software developers: You need to participate in a call for proposals for a big software project. You are responsible for the complete process from downloading and reading all documents for the call for proposals, making sense of the requirements, making a plan and an estimate, writing everything up and delivering your proposal in time and form at the right address. You cannot rely on the help of more experienced colleagues. You will probably feel overwhelmed and a bit helpless.

Now is the time to look for proven problem-solving frameworks that will at least help you coordinate your work and remind you about necessary steps that might go by the board otherwise. There are probably numerous frameworks out there, but I’ve found one to be easily applicable and reliable in the outcome. It’s the four steps of warfare. “Warfare” is a heavy word that isn’t in the dictionary of most people. It really means “to wage war” on somebody or something. But it doesn’t imply death, injury or even a “loser”. If you can wrap your head around the following sentence, we can easily forget its ancestry and follow the steps without any bloodshed: We are about to wage war on the call for proposals.

Being on a mission

We are now on a mission! Every mission starts with the most important piece of information: The mission statement. In this statement, the primary goals of the mission need to be declared as clear and unambiguous as possible. In our example, the mission statement might read like “I want to deliver a complete, believable and feasible proposal for the software project while adhering to all formalities”. It is worthwhile to write the mission statement down and keep it visible. This is your goal, this is why you wage war. Anything you do during the mission that doesn’t help you further your case in regard to the mission statement can be called a distraction (or in agile speak: “waste”).

Analyzing our example’s mission statement, we can conclude that we have two fields of work to cover: the content of the proposal and the formalities of the call. Both need to be covered successfully in order to achieve mission success. It is not enough to have a formidable proposal but send it in too late or without certain required characteristics. And it doesn’t do good to send something awful in that fulfills all technical requirements of the proposal but stands no chance because of its content. You’ve just discovered that your war will be fought on two fronts (content and formalities) and neglecting either one of them will not result in victory. That is an important discovery for the moment you employ your “troops” – time, attention, effort and material in our case.

The four steps

But slow down! We are far away from employing our troops! We first need to learn about the four steps of warfare. With our mission statement at hand, we have to make a plan for these steps:

  • Reconnaissance
  • Maneuver
  • Offensive
  • Defensive

Nearly every military mission can be broken down into these four steps in that order. We cover the first step in this blog post and the following three in the second part next week:

Step one: Reconnaissance

hunter looking through binocularsEvery warfare mission has important things at stake. There would be no mission otherwise, because each mission is expensive. With something big at stake, you want to reduce risk as much as possible. The military way to reduce risk is to gather knowledge about the enemy, to “increase intelligence”. Our “enemy” is the call for proposals with its deadline and rules and requirements. It is an easy enemy in a way, because all information is already made available in clear form and will not change over time. Or is it? Our first move should be to gather and revise all documents that tell us something about the call for proposals. Are we in possession of all available information? Nothing will break our neck more effectively than forgetting to read all documents. The sentence “I didn’t know that!” might sound like a good explanation why the mission failed, but it only indicates that you already failed in the reconnaissance step. Everything you do after a botched reconnaissance has a high risk of being ineffective, useless or downright counter-productive. You need to be sure to survey the complete terrain (read all the documents). A general that says “we don’t need to look behind this mountain, there will be nothing behind it” is in danger of failure as sure as you are if you say “that’s probably all information there is, what else should one want from me?”. Don’t underestimate your enemy! Just because you can download and read everything in regard to your call of proposals doesn’t mean it can be found at one place or will be conveniently available. Double-check that you’ve followed each hint about additional rules (like in general terms and conditions). Read all documents carefully!

When you’ve gathered a complete map of the terrain (have all rules and requirements in readable form), it’s time to mark the problematic features. Make a list of all formalities you need to adhere to. This list is already part of your battle plan. You will later need to employ resources to check off each point of this list. Mark all requirements that you find problematic or surprising. Those are like the strongholds on a battlefield. They need extra attention from you later on. Take your list of simple tasks and tack it on your mission board. If you didn’t have one yet, you’ll have it now. The mission board will look exactly like in the movies when you complete your first step. On top goes the mission statement, with your task list in whatever fashion suits you beneath it (some prefer the ordered list, some might draw a graph, whatever works for you). The mission board is for you and you only, nobody else needs to understand it. You’ve just created your headquarter! Now you have all ingredients to assemble your troops on the battlefield: you know the terrain, where the enemy resides, where you are and what your mission is.

Now is the time to get moving – in part two of this blog entry series next week. Stay tuned!

A simple yet useful project metric

In my years of managing software development projects, I’ve come to apply a simple metric to each project to determine its “personality”. The metric consists of only two aspects (or dimensions): success and noise. Each project strives to be successful in its own terms and each project produces a certain amount of “noise” while doing so. Noise, in my definition, is necessary communication above the minimum. A perfectly silent project isn’t really silent, there are just no communicated problems. That doesn’t mean there aren’t any problems! A project team can silently overcome numerous problems on their own and still be successful. The same team can cry for help at each and any hurdle and still fail in the long run. That would mean a lot of noise without effect. I call such a project a “Burning Ox”.

Success vs. Noise


As you can see, there are four types of projects with this metric. The desired type of project is the “White Knight” in the top-left quarter, while the “Burning Ox” in the bottom-right is the exact opposite. Let’s review all four types:

  • White Knight (silently on track): A project that is on track, tackles every upcoming challenge on its own, reports its status but omits the details and turns out to be a success is the dream of every project manager. You can let the team find its own way, document their progression and work on the long-term goals for the team and the product. It’s like sailing in quiet waters on a sunny day. Nothing to worry about and a pleasant experience all around.
  • Drama Queen (loud, but on track): This project is ultimately headed towards success, but every obstacle along the way results in emergency meetings, telephone conferences or e-mail exchanges. The number of challenges alone indicate that the team isn’t up to the task. You are tempted to micro-manage the project, to intervene to solve the problems and ensure success or at least progress. But you are bound to recognize some or even most problems as non-existent. The key sentence to say or think is: “Strange, nobody else ever had this problem and we’ve done it a dozen times before”. If you are a manager for several projects, the Drama Queens in your portfolio will require the majority of your time and attention. You’ll be glad when the project is over and “peaceful” times lie ahead.
  • Backstabber (silent and a failure): This is the biggest fear of every manager. The project seems alright, the team doesn’t report any problems and everything looks good. But when the cards need to be put on the table, you end up with a weak combination. It’s too late to do anything about the situation, the project is a failure. And it failed because you as the manager didn’t dig deeper, because you let them fool you. No! If you look closer, it failed because nobody dug deeper and everybody was in denial. You’ll see the warning signs in retrospective. You will become more paranoid in your next project. You’ll lose faith in the project status reports of your teams. You’ll inquire more and micro-manage the communication. You’ll become a skittish manager because of this unpleasant experience. Backstabber projects have horrendous costs for the social structure of a company.
  • Burning Ox (loud and failing): The name stems from an ancient war tactics when the enemy’s camp was overrun by a horde of oxen with burning torches bound to the horns. The panicked animals wreaked havoc along their way and started fires left and right. A Burning Ox is helpless in the situation, but takes it out on anybody and anything near it, too. This project is bound to fail, the team is in it way over their heads and no amount of support from your side or help from the outside can safe it. Well, experienced firefighters might work wonders, but they are expensive and rare (we know because we are often called in for this job). If you find a Burning Ox in your project portfolio (and you will know it, because a Burning Ox screams on the top of his lungs), prepare yourself for the inevitable: The project will fail, in scope (missing functionality), budget (higher costs) and/or time (delayed delivery). You better start with damage control now or make a call to a firefighter you can trust.

Easy assessment

This project management metric is not meant for deep inspection, but for easy assessment and quick communication. You can convey your desired communication style and the fact that everybody involved with the project is partly responsible for its success or failure. The metric states that too much detail is not helpful and too little detail can be disastrous. It also shows that loudly failing projects are not the fault of the project team alone (the ox cannot help being used as a living torch), but that the prerequisites of the project weren’t met.


If you are not a project manager, what can you learn from this blog post? Ask yourself if you require too much help from your manager, forcing him/her to switch into the micro-management gear, even if you could solve the problem yourself. If you cannot, ask yourself if you think that you can deliver the project in scope, time and budget or if you already smell the fire. If you can smell the fire, is your manager aware? Are you telling him/her in unclouded words about your perceived state of the project? Did you attempt to communicate your perception/feeling at least twice? If not, your manager might be shocked that he/she took care of a Backstabber project. A failing project is not your fault! You would only be to blame for the continued hiding of a known fact.

If you are a project manager, take a piece of paper, draw the metric’s chart and try to pin-point the position of all your projects. Be as honest and exact as possible. Is it really a Burning Ox or “just” a Drama Queen? Are your White Knights really above reproach or is their loyality questionable? What questions could you ask to try to unveil hidden problems, even those that nobody is aware of yet?

These quick, repeated assessments help me to manage my schedule and not forget about the silent projects because the loud projects always ellbow their way into my attention.

Recap of the Schneide Dev Brunch 2016-12-11

brunch64-borderedLast week at sunday, we held another Schneide Dev Brunch, a regular brunch on the second sunday of every other (even) month, only that all attendees want to talk about software development and various other topics. This brunch was so well-attended that we had to cramp around our conference table and gather all chairs on the floor. As usual, the main theme was that if you bring a software-related topic along with your food, everyone has something to share. Because we were so many, we established a topic list and an agenda for the event. As usual, a lot of topics and chatter were exchanged. This recapitulation tries to highlight the main topics of the brunch, but cannot reiterate everything that was spoken. If you were there, you probably find this list inconclusive:


We started with a report of one of our attendees who had studied in Finland for the last two years. He visited the Aalto university and shared a lot of cultural details about Finland and the Finnish people with us.

The two most important aspects of the report were sauna and singing. The Finnish love to visit a sauna, in fact, nearly every building has a functioning sauna. Every office building has a company sauna that will get visited often. So it might happen that your first visit of a company starts right in the sauna, naked with the bosses.

And the Finnish love singing so much that they usually start singing during the sauna session. There are open social events organized around singing together.

Alcohol plays a big role in Finland, mostly because the taxes makes it incredibly expensive to obtain a proper buzz. In the southern regions, much alcohol is imported from Russia or Estonia by ferry. There are even special ferry routes designed to be cost-neutral when shopping for alcohol. But alcohol isn’t the only thing that is made expensive with special taxes. Sugar and sugary food/drinks are heavily taxed, too. So it’s actually more expensive to eat unhealthy, which sounds like a good concept to counter some civilizational diseases.

The Finnish students often wear a special boilersuit during official events that identifies their affilition with their field of study and university. They apply patches and stickers to their suit when they have completed certain tasks or chores. It’s actually a lot like a military uniform with rank and campaign insignia. Only that the Finnish student boilersuit may not be cleaned or washed other than jumping into a body of water with you in it. And the Finnish lakes are frozen most of the year, with temperatures of -27 °C being nothing extraordinary.

As you probably have guessed right now, costs for rent and electricity are high. Our attendee enjoyed his time there, but is also glad to have the singing separated from the alcohol for the most part.

Lambdas and Concurrency

The next question revolved around the correlation between lambda expressions and concurrent execution of source code. The Vert.x framework relies heavily on lambdas and provides reactive programming patterns for Java. As such, it is event driven and non blocking. That makes it hard to debug or to reason about the backstory if an effect occurs in production. The traditional tools like stacktraces don’t tell the story anymore.

We took a deep dive into the concepts behind Optionals, Promises and Futures (but forgot to talk about the Expected type in C++). There is a lot of foggy implementation details in the different programming languages around these concepts and it doesn’t help that the Java Optional tries to be more than the C++ Optional, but doesn’t muster up the courage to be a full Monad. Whether deprecating the get()-method will make things better is open for discussion.

To give a short answer to a long discussion: Lambdas facilitate concurrent programming, but don’t require or imply it.

React.js and Tests

It was only a small step from the reactive framework Vert.x to the React.js framework in Javascript. One attendee reported his experiences with using different types of tests with the React framework. He also described the origin of the framework, mentioning the concept of Flux and Redux along the way.

Sorry if I’m being vague, but each written sentence about Javascript frameworks seem to have a halflife time of about six weeks. My take on the Javascript world is to lean back, grab some popcorn and watch the carnival from the terrace, because while we’re stuck with it forever, it is tragically unfortunate. Even presumed simple things like writing a correct parser for JSON end in nightmares.

It should be noted, though, that the vue.js framework entered the “assess” stage of the Thoughtworks Techradar, while AngularJS (or just Angular, as it should be called now) is in the “hold” stage.

Code Analysis

We also talked about source code analysis tools and plugins for the IDE. The gist of it seems to be that the products of JetBrains (especially the IntelliJ IDEA IDE) have all the good things readily included, while there are standalone products or plugins for other IDEs.


As usual, the Dev Brunch contained a lot more chatter and talk than listed here. The number of attendees makes for an unique experience every time. We are looking forward to the next Dev Brunch at the Softwareschneiderei in February 2017. We even have some topics already on the agenda (like a report about first-hand experiences with the programming language Rust). And as always, we are open for guests and future regulars. Just drop us a notice and we’ll invite you over next time.

It’s only Cores and Caches but I like it

759px-amd_am5x86_dieMost of our software development economy is based on a simple promise: The computing power (or “performance”) of a common computer will double every two years. This promise accompanied us for 40 years now, a time during which our computers got monitors, acquired harddisks and provided RAM beyond the 640 kB that was enough for nobody. In the more recent years, we don’t operate systems with one CPU, but four, eight or even twelve of them. So it came as a great irritation when ten years ago, Herb Sutter predicted that “The free lunch is over” and even Gordon Moore, the originator of Moore’s Law that forms the basis of our simple promise said that it will only hold true for ten to fiveteen more years. Or, in other words, until today.


That’s a bit unsettling, to say the least, and should be motivation enough to have a good look at everything we are doing. Intel, the biggest manufacturer of CPUs for computers, has indicated earlier this year that Moore’s Law cannot be fulfilled any longer. So, the free lunch is really over. And it turns out to have some hidden costs. One cost is a certain complacency, the conviction that things will continue to be as they were and that coding styles chiseled over years and decades hold an inherent value of experience.


Don’t get me wrong – there is great value in experience, but not all knowledge of the past is helpful for the future. Sometimes, fundamental things change. Just as the tables will eventually turn for every optimization trick, we need to reevaluate some axioms of our stance towards performance. Let me reiterate some common knowledge:

There are two types of performance inherently baked into your source code: Theoretical and practical performance.


The first type is theoretical performance, measured in O(n), O(n²) or even O(n!) and mostly influenced by the complexity class of the algorithm you are using. It will translate into runtime behaviour (like in the case of O(n!) your software is already dead, you just don’t know yet), but isn’t concerned with the details of your implementation. Not using an unnecessary high complexity class for a given problem will continue to be a valueable skill that every developer should master.

On the other hand, practical performance is measured in milliseconds (or nanoseconds if you are into micro-benchmarks and can pull off to measure them correctly) and can heavily depend on just a few lines in your source code. Practical performance is the observable runtime behaviour of your software on a given hardware. There are two subtypes of practical performance:

  • Throughput (How many operations are computed by the system in a given unit of time?)
  • Latency (How long does it take one operation to be computed by the system?)

If you run a service, throughput is your main metric for performance. If you use a service, latency is your main concern. Let me explain this by the metapher of a breakfast egg. If you want to eat your breakfast at a hotel buffet and the eggs are empty, your main concern is how fast you will get your freshly boiled egg (latency). But if you run the hotel kitchen, you probably want to cook a lot of eggs at once (throughput), even if that means that one particular egg might boil slightly longer as if you’d boiled each of them individually.


Those two subtypes are not entirely independent from each other. But the main concern for most performance based work done by developers is latency. It is relatively easy to measure and to reason about. If you work with latency-based performance issues, you should know about the latency numbers every programmer should know, either in visual form or translated to a more human time scale. Lets iterate some of the numbers and their scaled counterpart here:

  • 1 CPU cycle (0.3 ns): 1 second
  • Level 1 cache access (0.9 ns): 3 seconds
  • Branch mispredict (2.5 ns): 8 seconds
  • Level 2 cache access (2.8 ns): 9 seconds
  • Level 3 cache access (12.9 ns): 43 seconds
  • Main memory access (120 ns): 6 minutes
  • Solid-state disk I/O (50-150 μs): 2-6 days
  • Rotational disk I/O (1-10 ms): 1-12 months

We can discuss any number in detail, but the overall message stands out nonetheless: CPUs are lightning fast and caches are the only system components that can somewhat keep up. As soon as your program hits the RAM, your peak performance is lost. This brings us to the main concept of latency optimization:

Your program’s latency is ultimately decided by your ability to decrease cache misses.

You can save CPU cycles by performing clever hacks, but if you are able to always read your data (and code) from the cache, you’ll be 360 times faster than if your program constantly has to read from RAM. Your source code doesn’t have to change at all for this to happen. A good compiler and/or optimizing runtime can work wonders if you adhere to your programming language’s memory model. In reality, you probably have to rearrange your instructions and align your data structures. That’s the performance optimization of today, not the old cycle stinting. The big challenge is that none of these aspects are visible on the source code level of your program. We have to develop our programs kind of blindfolded currently.


One way how we’ve held up Moore’s Law in the last ten years was the introduction of multiprocessor computing into normal computers. If you cram two CPUs onto the die, the number of transistors on it has doubled. A single-threaded program doesn’t run any faster, though. So we need to look at concurrent programming to unlock the full power of our systems. Basically, there are two types of concurrent programming, deliberate and mechanical.

  • Deliberate concurrent programming means that you as the developer actively introduce threads, fibers or similar concepts into your source code to control parallel computation.
  • Mechanical concurrent programming means that your source code can be parallelized by the compiler and/or runtime and/or the hardware (e.g. hyper-threading) without changing the correctness of your program.

In both types of concurrent programming, you need to be aware about the constraints and limitations of correct concurrency. It doesn’t matter if your program is blazingly fast and utilizes all cores if the result is wrong or only occasionally correct. Once again, the memory model of your programming language is a useful set of rules and abstractions to guide you. Most higher-level concurrency models like actors narrow your possibilities even further, with functional programming being one of the strictest (and most powerful ones).

In the field of software development, we are theoretically well-prepared to take on the task of pervasive concurrent programming. But we need to forget about the good old times of single-core confirmability and embrace the chaotic world of raw computing power, the world of cores and caches.

Cores ‘n’ Caches

This is our live now: We rely on Cores ‘n’ Caches to feed us performance, but the lunch isn’t free anymore. We have to adapt and adjust, to rethink our core axioms and let go of those parts of our experience that are now hindrances. Just like Rock ‘n’ Roll changed the rules in the music business, our new motto changes ours.

Let’s rock.

Children behind the wheel

A few weeks ago, I read a funny news article about a 11 years old boy who stole a bus and drove the normal route with it. When the police stopped him, he had already picked up some passengers and somehow managed to only inflict minor damages along the way. The whole story (in german) can be read here.

Author: Vitaly Volkov, Волков Виталий Сергеевич (user kneiphof) blog entry is not about the unheeding passengers, it’s about the little boy and his mindset. This mindset exists in the business world, too. It’s the mixture of “what could possibly go wrong?” with “I’m totally able to pull this off” and a large dose of “everybody else is surely faking it, too”. In the context of the Dunning-Kruger effect, this mixture is called “unskilled and unaware of it”. It’s a dangerous situation for both the employee and the employer, because neither of them can properly evaluate the actual risk.

The Dunning-Kruger effect

Let’s start with the known theory. The Dunning-Kruger effect describes a cognitive bias in which unskilled individuals assess their ability (in the context of a given skill) much higher than it really is and highly skilled individuals tend to underestimate their (relative) competence. The problem is not that real experts tend to be modest about their expertise. The real problem is that “if you’re incompetent, you can’t know you’re incompetent. The skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is.”

So in short: Being unskilled in a certain area probably means you don’t really know that you are unskilled.

Or, translated to our young bus driver: If you don’t know anything about driving a bus, you certainly think you are as much a decent bus driver as the man behind the wheel. It looks easy enough from the passenger seat.

The effect in practice

Why should this bother us in software development? Our education system ensures that we are exposed to enough development practice so that we can counter the “unaware of it” part of the Dunning-Kruger effect. But it isn’t effective enough, at least that’s what I see from time to time.

Every once in a while, I have the opportunity to evaluate an existing code base. Most of the time, it produces a working, profitable application, so it cannot be said to be a failure. Sometimes however, the code base itself is so convoluted, bloated and riddled with poor implementation choices that it absolutely cannot be developed any further without a high risk of regression bugs and/or absurd amounts of developer time for little changes.

These hopeless source codes have one thing in common: they are developed by one person and one person alone. This person has developed for months or even years, showing progress and reporting no problems and suddenly resigned, often shortly before a major milestone in the project like going live with the first version or announcing the next version. The code base now lies abandonded and needs to be adopted. And while no code base is perfect (or should even try to be), this one reeks of desperation and frustration. Often, the application itself is not very demanding, but the source code makes it appear to be.

A good example of this kind of project is my scrap metal tale (in three parts) from five years ago:

A more recent case is littered with inline comments that celebrate small victories of the developer:

  • 5 lines of convoluted, contradicatory statements
  • 3 lines commented out
  • 1 comment line stating “YES! This is finally working! Super!”
  • Still three obvious bugs, resource leaks or security flaws in these few lines alone

The most outrageous (and notorious) case might be the Brillant Paula Bean from the Daily WTF, but this code base is at least readily comprehensible.

The origins of the effect

I think a lot of the frustration, desperation, anxiety and outright fear that I can sense through the comments and code structure was really felt by the original author. It must have been incredibly hard to stay on course, work hard and come up with solutions in the face of imminent deadlines, ever-changing requirements and the lingering fear that you’re just not up to the task. Except that we’ve just learned that developers in the “unskilled and unaware of it” state won’t feel the fear. That’s the origin of all the bad code: The absolute conviction that “it’s not me, it’s the problem, the domain, the language, the compiler, the weather and everything else”. Programming is just hard. Nobody else could do this better. It’ll work in the end. Those “minor problems” (like never actually speaking to the hardware, hard-coded paths and addresses, etc.) will be fixed at the last moment. There’s nothing wrong with an occassional exception stack trace in the logfile and if it bothers you, I can always make the catch-block empty.

The most obvious problem is that these developers think that this is how everybody else develops software, too. That we all don’t bother with concurrency correctness, resource lifecycle management, data structures, graphical user interface design, fault tolerance or even just basic logging. That all programming is hard and frustrating. That finding out where to insert a sleep statement to quench that pesky exception is the pinnacle of developer ingenuity. That things like automated tests, code metrics, continuous integration or even version control are eccentric fads that will pass by and be forgotten soon, so no need to deal with it. That we all just fake it and dread the moment our software is used in the wild.

A possible remedy

The “unskilled and unaware of it” developer isn’t dumb or hopeless, he’s just unskilled. The real tragedy is that he doesn’t have a mentor that can alleviate the biggest problems in the code and show better approaches. The unskilled lonesome developer cannot train himself. A good explanation for this novice “lock-in” can be found in the Dreyfus Model of Skill Acquisition (I recommend you watch the excellent talk on this topic by Dave Thomas): Novices lack the skills for proper self-assessment and cannot learn from their mistakes (as stated by the Dunning-Kruger effect, too). They also cannot recognize them as “their” mistakes or even “mistakes”. They need outside feedback (and guidance) to advance themselves. A mentor’s role is to give exactly that.


If you find yourself in a position of being a “skilled and fairly aware of it” developer, please be aware that you’ve probably been mentored sometimes in the past. Pass it on! Be the mentor for an aspiring junior developer.

If you suspect that you might fall in the “unskilled” category of developers, don’t despair! Being aware of this is the first and most important step. Now you can act strategically to improve your skill. There is a whole book giving you invaluable advice: Apprenticeship Patterns: Guidance for the Aspiring Software Craftsman by Dave Hoover and Adewale Oshineye. Two prominent advices from the book are “Be the Worst (of your team)” and “Find Mentors“. And my most prominent advice? “Don’t stick it out alone“.

Programming is (or should be) fun after all.