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The Dark Art of Debugging
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eojthebrave
May 22, 2015
Technology
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580
The Dark Art of Debugging
A talk about developing the soft-skills required to be a good software debugger.
eojthebrave
May 22, 2015
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Transcript
The Dark Art of Debugging php[tek] 2015 - Chicago Joe
(@eojthebrave) Shindelar https://joind.in/event/view /3183
Hi. I’m Joe Shindelar @eojthebrave
5 Minutes - GO! + Bugs are inevitable + Debugging
is a science + Replicate, Isolate, Understand, Fix + Practice …
So … where do bugs come from?
Software: Is a set of written instructions provided for a
computer to interpret and use to accomplish a task.
Software: Is a set of written instructions provided for a
computer to interpret and use to accomplish a task. Bugs: Are the defects that arise when those instructions are incorrectly translated.
“There’s a space between zero and one, between the way
the machine counts and thinks and the way we count and think. When you search for explanations for software’s bugs and delays and stubborn resistance to human desires, that space is where you’ll find them.” - Scott Rosenberg -Dreaming In Code
The ONLY way to be a zero bug programmer is
to not write any code.
Debugging is a practical application of both technical skills and
analytical abilities
This presentation is not about tools. But tools play an
important roll in debugging. Learn your tools. Use your tools.
+ Replicate + Isolate + Understand + Fix
Ready? Fire! Aim. Give yourself 10 minutes to jump in
and dirty- debug. But STOP before you go crazy.
STEP ONE Replicate the problem
It is a capital mistake to theorize before one has
data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. - Sherlock Holmes Quote -A Scandal in Bohemia
Replicate + Keep a log
Replicate + Keep a log + Get it to fail
Replicate + Keep a log + Get it to fail
+ Lay a trap
Replicate + Keep a log + Get it to fail
+ Lay a trap + Stimulate. Don’t simulate
Replicate + Keep a log + Get it to fail
+ Lay a trap + Stimulate. Don’t simulate + Automate the failure
Goal: Generate a list of steps
STEP TWO Isolate the problem
There is nothing more deceptive than an obvious fact. -
Sherlock Holmes Quote - The Bascombe Valley Mystery
Isolate + Avoid easter egging
Isolate + Avoid easter egging + Check the plug
Isolate + Avoid easter egging + Check the plug +
Divide & conquer
Isolate + Avoid easter egging + Check the plug +
Divide & conquer + Change one thing at time
Isolate + Avoid easter egging + Check the plug +
Divide & conquer + Change one thing at time + Stop thinking and look
Goal: Explain what is causing the problem to occur. Include
details about application state, time, and inputs.
STEP THREE Understand the problem
Nothing clears up a case so much as stating it
to another person. - Sherlock Holmes Quote - Silver Blaze
Understand + Brain games
Avoid confirmation bias Beware the availability heuristic
Understand + Brain games + Don’t assume anything. Ever
Understand + Brain games + Don’t assume anything. Ever +
Practice tempered humility
Understand + Brain games + Don’t assume anything. Ever +
Practice tempered humility + Read the manual
“Why bother, I can look it up in the Phone
book.” - Einstein
Understand + Brain games + Don’t assume anything. Ever +
Practice tempered humility + Read the manual + Ask for help
Goal: Explain the root cause, and how your proposed fix
will solve the problem.
STEP FOUR Fix the problem
Eliminate all other factors, and the one which remains must
be the truth. - Sherlock Holmes Quote - The Sign of Four
Fix + Don’t stop until you’re done
Fix + Don’t stop until you’re done + Establish causality
Fix + Don’t stop until you’re done + Establish causality
+ Test your fix
Goal: Close the ticket!
+ Replicate + Isolate + Understand + Fix
“The greats weren't great because at birth they could paint.
The greats were great cause they paint a lot.” - Macklemore
The Dark Art of Debugging php[tek] 2015 - Chicago Joe
(@eojthebrave) Shindelar https://joind.in/event/view /3183