A Practical Taxonomy of Bugs and How to Squash Them-We Rise 2017

A Practical Taxonomy of Bugs and How to Squash Them-We Rise 2017

These are the slides I used for We Rise Tech, Women Who Code Atlanta's first conference.

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Kylie

June 23, 2017
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Transcript

  1. A COMMON TAXONOMY OF BUGS AND HOW TO SQUASH THEM

  2. Instinctual Indications…6 Research Methods…9 Practical Taxonomy…13 Bohrbug…17 Schrödinbug…25 Fractalbug…24 Heisenbug…35

    Mandelbug…44 Resources…55 Table of Contents
  3. Debugging Skills

  4. “As you familiarize yourself with the application, you’ll build up

    some debugging instincts"
  5. “Whenever I see something like this happening, the first thing

    I do is scan the logs to see if this process is completing or is sending a weird message.”
  6. None
  7. Debugging Instincts “ ”

  8. None
  9. None
  10. “Whenever I see something like this happening, the first thing

    I do is scan the logs to see if this process is completing or is sending a weird message.”
  11. “Whenever I see #{x}, I always check #{y}”

  12. Instincts are just internalized rulesets

  13. Research Methods • containment sometimes takes priority over squashing

  14. Research Methods • containment sometimes takes priority over squashing •

    we can only work with facts
  15. Research Methods • containment sometimes takes priority over squashing •

    we can only work with facts • we can’t squash every bug in this talk
  16. Observable Attributes

  17. Phenetics { ]

  18. Warning: Contrived Scenarios Ahead

  19. A COMMON TAXONOMY OF BUGS AND HOW TO SQUASH THEM

  20. Taxonomy of Bugs Upsettingly Observable Wildly Chaotic {

  21. Upsettingly Observable Bugs

  22. Wildly Chaotic Bugs

  23. How to Squash Them

  24. upsettingly observable bug #1 UPSETTINGLY OBSERVABLE

  25. Observable Attributes is the bug observable in production?

  26. Observable Attributes is the bug observable in production? can it

    be reproduced locally?
  27. Observable Attributes is the bug observable in production? can it

    be reproduced locally? does it seem to be restricted to one area?
  28. Bohrbug deterministic, highly reproducible UPSETTINGLY OBSERVABLE

  29. Bohrbug Commonly found in code,sometimes on server UPSETTINGLY OBSERVABLE

  30. Bohrbug likes to hide in complex branching in functions, classes

    or config UPSETTINGLY OBSERVABLE
  31. Bohrbug In the wild: validation UPSETTINGLY OBSERVABLE

  32. Bohrbug UPSETTINGLY OBSERVABLE Easy to squash

  33. Reproduction & Resolution replicate locally and in test UPSETTINGLY OBSERVABLE

  34. Reproduction & Resolution replicate locally and in test write the

    simple solution UPSETTINGLY OBSERVABLE
  35. Reproduction & Resolution replicate locally and in test write the

    simple solution rewrite to be highly readable and extendable UPSETTINGLY OBSERVABLE
  36. Bohrbug UPSETTINGLY OBSERVABLE

  37. Bohrbug UPSETTINGLY OBSERVABLE

  38. upsettingly observable bug #2 UPSETTINGLY OBSERVABLE

  39. Observable Attributes how does this work?

  40. Observable Attributes how does this work? does this work?

  41. Observable Attributes how does this work? does this work? wait,

    what is this even testing?
  42. Observable Attributes how does this work? does this work? wait,

    what is this even testing? did this ever work?
  43. Schrödinbug stick-like body appendages look like twigs UPSETTINGLY OBSERVABLE

  44. Schrödinbug Likes to pretend to be working code. On close

    inspection, reveals itself to be a bug. UPSETTINGLY OBSERVABLE
  45. Schrödinbug UPSETTINGLY OBSERVABLE Type I. Type II.

  46. Schrödinbug Type I. Code that never worked UPSETTINGLY OBSERVABLE

  47. Schrödinbug Type I. Reveal themselves via side-effects UPSETTINGLY OBSERVABLE

  48. Schrödinbug Type I. In the wild: UI shows update but

    database entry not updated. UPSETTINGLY OBSERVABLE
  49. Schrödinbug Type II. Code that doesn’t work how you thought

    UPSETTINGLY OBSERVABLE
  50. Schrödinbug Type II. In the wild: Same function being called

    multiple times UPSETTINGLY OBSERVABLE
  51. Basic Reproduction & Resolution replicate locally and in test write

    the simple solution rewrite to be highly readable and extendable UPSETTINGLY OBSERVABLE
  52. -You “How can I reproduce this without knowing exactly what

    is happening?”
  53. Logging as Verification Tool

  54. Git Bisect Tool

  55. Reproduction & Resolution reproduce the “broken” state locally and in

    test
  56. Reproduction & Resolution reproduce the “broken” state locally and in

    test add log statements until you can verify what causes the broken state.
  57. Reproduction & Resolution reproduce the “broken” state locally and in

    test add log statements until you can verify what causes the broken state. if the bug did work at some point, find the point at which it did work.
  58. Reproduction & Resolution reproduce the “broken” state locally and in

    test add log statements until you can verify what causes the broken state. if the bug did work at some point, find the point at which it did work. write tests to represent the configuration and flow of the fixed state
  59. Schrödinbug UPSETTINGLY OBSERVABLE

  60. Schrödinbug UPSETTINGLY OBSERVABLE

  61. wildly chaotic bug #1 WILDLY CHAOTIC

  62. Observable Attributes Does it appear non-deterministic?

  63. Observable Attributes Does it appear non-deterministic? Does it seem to

    disappear once you observe or debug it?
  64. Heisenbug “now you see it, now you don’t” WILDLY CHAOTIC

  65. Heisenbug WILDLY CHAOTIC Type I. Type II.

  66. Heisenbug Type I. WILDLY CHAOTIC Lives in code

  67. Heisenbug Type II. WILDLY CHAOTIC Lives in data

  68. -You “How can I reproduce this without testing on production?”

  69. Profiling for Verification https://kcachegrind.github.io/html/CallgrindFormat.html Tool

  70. FLAME GRAPHS http://www.brendangregg.com/FlameGraphs/cpu-mysql-updated.svg Tool

  71. Heisenbug Type I. WILDLY CHAOTIC Profiling can reveal what is

    being called and when
  72. Heisenbug Type II. WILDLY CHAOTIC Profiling can reveal how much

    time is being spent.
  73. Reproduction & Resolution use profiling to find the trigger state

  74. Reproduction & Resolution use profiling to find the trigger state

    use the app (not fixtures or DB manipulation) to get the data in this state
  75. Reproduction & Resolution use profiling to find the trigger state

    use the app (not fixtures or DB manipulation) to get the data in this state recreate that state in test
  76. Reproduction & Resolution use profiling to find the trigger state

    use the app (not fixtures or DB manipulation) to get the data in this state recreate that state in test follow borhbug instruction
  77. Heisenbug WILDLY CHAOTIC

  78. Heisenbug WILDLY CHAOTIC

  79. wildly chaotic bug #2 WILDLY CHAOTIC

  80. Observable Attributes is everything broken?

  81. Observable Attributes is everything broken? all of it?

  82. Observable Attributes is everything broken? all of it? send help??

  83. Mandelbug WILDLY CHAOTIC

  84. Mandelbug seems like everything is broken at once WILDLY CHAOTIC

  85. Mandelbug people are very upset with you WILDLY CHAOTIC

  86. Mandelbug likely an issue with your system, not code WILDLY

    CHAOTIC
  87. “The bug is huge and everywhere at once. SQL: could

    not connect to server: Connection refused was bubbling up all over the place. Jobs won’t run, emails won’t send, every submit button on the site fatal errored.” on-call log WILDLY CHAOTIC
  88. Disk Usage Tool df -h

  89. Logging as Verification Tool

  90. Reproduction & Resolution use df -h to find if all

    the storage is being use
  91. Reproduction & Resolution use df -h to find if all

    the storage is being use attempt to connect to server & view logs
  92. Reproduction & Resolution use df -h to find if all

    the storage is being used attempt to connect to server & view logs can that be restarted, rotated or killed at this time?
  93. Mandelbug WILDLY CHAOTIC

  94. Mandelbug WILDLY CHAOTIC

  95. A Practical Taxonomy of Bugs Upsettingly Observable Wildly Chaotic {

    bohrbug schrödinbug mandelbug heisenbug
  96. “Debugging Instincts”

  97. “Debugging Instincts”

  98. Debugging Skills

  99. Observe & Classify

  100. Verify with logging and time travel

  101. Verify without changing state by profiling

  102. Use server tools to observe entire process

  103. Observe & Classify Verify with logging and time travel Verify

    without changing state by profiling Use server tools to observe entire process
  104. Build Up Your Own Toolkit and Share it

  105. Resources & Further Study • “Linux Debugging Tools I Love”,

    Julia Evans • Systems Performance, Brendan Gregg • “Why Do Computers Stop and What Can Be Done About It?”, Jim Gray • “Debug Patterns for Efficient High- levelSystemC Debugging”, Frank Rogin, Erhard Fehlauer, Christian Haufe, Sebastian Ohnewald
  106. None