A Common Taxonomy of Bugs and How to Squash Them-RubyConfAU

Catching software bugs is a mysterious magic, unknowable by science and untouchable by process.

False! Programming bugs, like real bugs, can be organized into a taxonomy. Come with me and I’ll show you how classification can help you build “programmer’s instinct” into a logical debugging process.

Transcript

1. A COMMON TAXONOMY OF BUGS AND HOW TO SQUASH THEM
2. Use Your Imagination
3. Instinctual Indications…6 Research Methods…9 Practical Taxonomy…13 Bohrbug…17 Schrödinbug…25 Fractalbug…24 Heisenbug…35 Mandelbug…44 Resources…55 Table of Contents
4. Debugging Skills
5. “As you familiarize yourself with the application, you’ll build up some debugging instincts"
6. “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.”
8. Debugging Instincts “ ”
11. “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.”
12. “Whenever I see #{x}, I always check #{y}”
13. Instincts are just internalized rulesets
14. Research Methods • containment sometimes takes priority over squashing
15. Research Methods • containment sometimes takes priority over squashing • we can only work with facts
16. Research Methods • containment sometimes takes priority over squashing • we can only work with facts • we can’t squash every bug in this talk
17. Observable Attributes
18. Phenetics { ]
19. Warning: Contrived Scenarios Ahead
20. A COMMON TAXONOMY OF BUGS AND HOW TO SQUASH THEM
21. Taxonomy of Bugs Upsettingly Observable Wildly Chaotic {
22. Upsettingly Observable Bugs
23. Wildly Chaotic Bugs
24. How to Squash Them
25. upsettingly observable bug #1 UPSETTINGLY OBSERVABLE
26. Observable Attributes is the bug observable in production?
27. Observable Attributes is the bug observable in production? can it be reproduced locally?
28. Observable Attributes is the bug observable in production? can it be reproduced locally? does it seem to be restricted to one area?
29. Bohrbug deterministic, highly reproducible UPSETTINGLY OBSERVABLE
30. Bohrbug Commonly found in code,sometimes on server UPSETTINGLY OBSERVABLE
31. Bohrbug likes to hide in complex branching in functions, classes or config UPSETTINGLY OBSERVABLE
32. Bohrbug In the wild: validation UPSETTINGLY OBSERVABLE
33. Bohrbug UPSETTINGLY OBSERVABLE Easy to squash
34. Reproduction & Resolution replicate locally and in test UPSETTINGLY OBSERVABLE
35. Reproduction & Resolution replicate locally and in test write the simple solution UPSETTINGLY OBSERVABLE
36. Reproduction & Resolution replicate locally and in test write the simple solution rewrite to be highly readable and extendable UPSETTINGLY OBSERVABLE
37. Bohrbug UPSETTINGLY OBSERVABLE
38. Bohrbug UPSETTINGLY OBSERVABLE
39. upsettingly observable bug #2 UPSETTINGLY OBSERVABLE
40. Observable Attributes how does this work?
41. Observable Attributes how does this work? does this work?
42. Observable Attributes how does this work? does this work? wait, what is this even testing?
43. Observable Attributes how does this work? does this work? wait, what is this even testing? did this ever work?
44. Schrödinbug stick-like body appendages look like twigs UPSETTINGLY OBSERVABLE
45. Schrödinbug Likes to pretend to be working code. On close inspection, reveals itself to be a bug. UPSETTINGLY OBSERVABLE
46. Schrödinbug UPSETTINGLY OBSERVABLE Type I. Type II.
47. Schrödinbug Type I. Code that never worked UPSETTINGLY OBSERVABLE
48. Schrödinbug Type I. Reveal themselves via side-effects UPSETTINGLY OBSERVABLE
49. Schrödinbug Type I. In the wild: UI shows update but database entry not updated. UPSETTINGLY OBSERVABLE
50. Schrödinbug Type II. Code that doesn’t work how you thought UPSETTINGLY OBSERVABLE
51. Schrödinbug Type II. In the wild: Same function being called multiple times UPSETTINGLY OBSERVABLE
52. Basic Reproduction & Resolution replicate locally and in test write the simple solution rewrite to be highly readable and extendable UPSETTINGLY OBSERVABLE
53. -You “How can I reproduce this without knowing exactly what is happening?”
54. Logging as Verification Tool
55. Git Bisect Tool
56. Reproduction & Resolution reproduce the “broken” state locally and in test
57. Reproduction & Resolution reproduce the “broken” state locally and in test add log statements until you can verify what causes the broken state.
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.
59. 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
60. Schrödinbug UPSETTINGLY OBSERVABLE
61. Schrödinbug UPSETTINGLY OBSERVABLE
62. wildly chaotic bug #1 WILDLY CHAOTIC
63. Observable Attributes Does it appear non-deterministic?
64. Observable Attributes Does it appear non-deterministic? Does it seem to disappear once you observe or debug it?
65. Heisenbug “now you see it, now you don’t” WILDLY CHAOTIC
66. Heisenbug WILDLY CHAOTIC Type I. Type II.
67. Heisenbug Type I. WILDLY CHAOTIC Lives in code
68. Heisenbug Type II. WILDLY CHAOTIC Lives in data
69. -You “How can I reproduce this without testing on production?”
70. Profiling for Verification https://kcachegrind.github.io/html/CallgrindFormat.html Tool
71. FLAME GRAPHS http://www.brendangregg.com/FlameGraphs/cpu-mysql-updated.svg Tool
72. Heisenbug Type I. WILDLY CHAOTIC Profiling can reveal what is being called and when
73. Heisenbug Type II. WILDLY CHAOTIC Profiling can reveal how much time is being spent.
74. Reproduction & Resolution use profiling to find the trigger 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
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
77. 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
78. Heisenbug WILDLY CHAOTIC
79. Heisenbug WILDLY CHAOTIC
80. wildly chaotic bug #2 WILDLY CHAOTIC
81. Observable Attributes is everything broken?
82. Observable Attributes is everything broken? all of it?
83. Observable Attributes is everything broken? all of it? send help??
84. Mandelbug WILDLY CHAOTIC
85. Mandelbug seems like everything is broken at once WILDLY CHAOTIC
86. Mandelbug people are very upset with you WILDLY CHAOTIC
87. Mandelbug likely an issue with your system, not code WILDLY CHAOTIC
88. “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
89. Disk Usage Tool df -h
90. Logging as Verification Tool
91. Reproduction & Resolution use df -h to find if all the storage is being use
92. Reproduction & Resolution use df -h to find if all the storage is being use attempt to connect to server & view logs
93. 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?
94. Mandelbug WILDLY CHAOTIC
95. Mandelbug WILDLY CHAOTIC
96. A Practical Taxonomy of Bugs Upsettingly Observable Wildly Chaotic { bohrbug schrödinbug mandelbug heisenbug
97. “Debugging Instincts”
98. “Debugging Instincts”
99. Debugging Skills
100. Observe & Classify
101. Verify with logging and time travel
102. Verify without changing state by profiling
103. Use server tools to observe entire process
104. Observe & Classify Verify with logging and time travel Verify without changing state by profiling Use server tools to observe entire process
105. Build Up Your Own Toolkit and Share it
106. 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