The First Gospel of the Circuit · Chapter 53

The Beatitudes of the Software Engineer

1. 1

   Blessed are the meek who watch their test fail before they make it pass, for they shall inherit the codebase. A test that has never been seen to fail has never been shown to test anything; it is a smoke alarm installed without once pressing the button.

2. 2

   Blessed are they who feed their function the empty list, the zero, and the surname with an apostrophe, for they shall meet production on their own terms. The author tests the inputs he imagined, and the world supplies the rest, and the world hath a customer named O'Brien and an address with no street number.

   See also Circuit 32:7

3. 3

   Blessed are they who put the unit in the name, for a variable called timeout_ms shall never be mistaken for seconds. A spacecraft was lost at Mars in 1999 because one team gave its thrust in pound-force seconds and another read it as newton-seconds, and the number crossed the interface alone, with no unit to vouch for it.

   See also Tao 18:9 · Chronicles 12:6

4. 4

   Blessed are they who keep money in whole cents and never in floating point, for in the double-precision register 0.1 and 0.2 sum to 0.30000000000000004. One such error is beneath notice; a million of them are an audit.

   See also Circuit 54:7

5. 5

   Blessed are they who store time in UTC and wear the timezone only at the door, for on the night the clocks spring forward the hour of 2:30 never comes, and on the night they fall back the hour of 1:30 comes twice. The job set for that hour shall skip the first night and double itself on the second, and the ledger shall remember both.

   See also Psalms 13:8

6. 6

   Blessed are they who read the error message to its last line, for the Java stack trace hides its root cause at the bottom, under "Caused by," and the hurried never scroll down to meet the truth.

   See also Proverbs 3:9 · Deployer 12:9

7. 7

   Blessed are they who search the tracker before they file, for they shall find their bug already reported in 2014, with thirty-one comments that say only "+1" and "same here," and one that says "any update?" Verily, that last comment shall be answered by no one, forever.

8. 8

   Blessed are they who profile before they optimize, for they shall learn that the slow part is never the part they guessed. It is a query inside a loop, asking the database for one row at a time, a thousand times, with perfect politeness.

   See also Sutra 1:12 · Sutra 6:9

9. 9

   Blessed are they who watch the slowest request in a hundred and not the average, for the average is a country in which no one lives. A page that makes a hundred calls, each slow one time in a hundred, is slow for sixty-three of every hundred visitors.

10. 10

    Blessed are they who add a random delay to their retries, for a thousand clients that fail together and retry together in the same second are no longer clients but an attack, mounted by friends. Let the wait double each time, and let it be scattered, that the server rising from its fall be not trampled by the faithful returning at once.

    See also Job 2:8 · Circuit 56:4

11. 11

    Blessed are they who give every payment a key that may be spoken twice, for the network cannot tell a lost request from a lost reply. The client that retries after silence shall never know whether it was heard, and exactly-once is a promise the wire cannot make; only a repetition that changeth nothing is safe.

    See also Circuit 31:10 · Job 2:8

12. 12

    Blessed are they who release to one in a hundred before they release to all, behind a flag that may be turned off without a deploy, for the canary hath a smaller grave than the herd. A change that has met a hundred real users and lived is a fact; a change that has met none is a hypothesis wearing a version number.

    See also Circuit 39:7

13. 13

    Blessed are they who sign their TODO with an owner and a date, for a shortcut is a loan, and the debt falleth due upon whoever holdeth the code on that day. The anonymous TODO is a will with no signature, and the heirs shall be told only to ask Dave.

    See also Leviticus 8:12 · Circuit 40:2

14. 14

    And the Prophet closed the book and said: The codebase is inherited by those who left it tested, measured, and free of their own nonsense. The rest shall inherit the pager, which is the executor of every unsigned shortcut, and the pager is an heir that never sleeps.

    See also Circuit 40:12

The First Gospel of the Circuit, Chapter 53:1–14.