22. Oktober 2008

I am a Professional Paranoid

I am a software developer. I make things work. Sometimes I make a mistake. But only about once per year. I mean serious mistakes, a wrong Architecture, a buggy code line that requires an emergency release. That's OK, you think. But...

...there are 10 developers. Each of them does very good work. They deliver solid, tested, working code. They make only very few mistakes. Only one each year. I mean the very serious errors. This makes an emergency release every month. Each new release is followed by a bug fix release. Each new feature is retarded by the emergency release of the previous feature.

There are 6 big features every year. Each feature has >1 operating components. This makes 30 components in 2 years, easily 50 in 3 years. If a single components runs into problems once per year, then after 3 years operating plays firefighter every other week. But operating is already busy maintaining and expanding the operation without serious application problems. They have their own operational problems.

All this makes me 10 times more paranoid.

Of course you make mistakes, anyone does. We test, check, and we find and fix them. But still one per year might slip through. That's still too much. We need methods to eradicate them. My methods are paranoid programming, good architecture, expectation tests, slow down, and 4-eyes.

Paranoid programming and good architecture are classics. 4-eyes is useful in extreme cases and dangerous situations. You want to drop the backup database? Ask someone else, if the statement is correct. She will notice that you are actually dropping the live database.

Expectation testing means, that you plan what to expect from a test. Think of the result before you click the button. Do not interpret test results. Plan the result, make a theory, and confirm the theory. The system tells you facts. And facts are powerful arguments. They can easily convince your brain, that everything is OK. Do not let them convince you. Let the facts confirm your expectations. You are the boss. You tell what happens, before it happens.

Slow down means that you do not hurry delivery. Coding should be quick, dynamic, agile. But delivery, be it deployment, delivery of results or code check-in may be slow. Take your time to think about what you are doing and if it is really brilliant. Stand up, walk around the chair, sit back, think. Take the time. It's only 3 minutes. It's nothing compared to the work before, nothing compared to the consequences of failure.

The goal is NO MISTAKES. That's impossible. But if we do everything and more to make NO MISTAKES, then we might end up at really only one per year, per developer. That would be fine.

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