Release It!, 2nd Edition

Wrapping Up

In time, even shockingly unlikely combinations of circumstances will eventually occur. If you ever catch yourself saying, “The odds of that happening are astronomical,” or some similar utterance, consider this: a single small service might do ten million requests per day over three years, for a total of 10,950,000,000 chances for something to go wrong. That’s more than ten billion opportunities for bad things to happen. Astronomical observations indicate there are four hundred billion stars in the Milky Way galaxy. Astronomers consider a number “close enough” if it’s within a factor of 10. Astronomically unlikely coincidences happen all the time.

Failures are inevitable. Our systems, and those we depend on, will fail in ways large ...