Based on a book written by David. J. Agans, this presentation outlines the basic rules of debugging.

1. Debugging:
9 Indispensable Rules
(Rules 1-3)
- Mudabbir Warsi
(ITCM Dev, CA Technologies)

2. Understand the System
“It is not so impossible, however, that a man should possess all knowledge which is likely to be
useful to him in his work, and this, I have endeavored in my case to do”.
– Sherlock Holmes
Read the manual
Remember Murphy’s Law
Know what is reasonable
Know the lay of the land
Know your tools
o Choose the right tools
o Use the tool correctly
o Interpret the results correctly
o Understand the limitations of your tools
Debugging: 9 indispensable rules. 07/07/2011 Copyright (c) 2011 CA. All rights reserved.

3. Make it fail
“There is nothing like first-hand evidence”.
– Sherlock Holmes
How to make it fail?
o Start at the beginning
o No detail is insignificant
o Stimulate the failure. Don’t simulate the failure
o What if it’s intermittent?
o What if it’s still intermittent?
Why to make it fail?
o Did you fix it, or Did you get lucky?
o But “that” can’t happen!
Debugging: 9 indispensable rules. 07/07/2011 Copyright (c) 2011 CA. All rights reserved.

4. Quit thinking and look
“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
See the failure
My eyes are open….Now what?
o Design Instrumentation in
o Build Instrumentation in later
The Heisenberg uncertainty principle
Guess, but look before you fix
Debugging: 9 indispensable rules. 07/07/2011 Copyright (c) 2011 CA. All rights reserved.

5. Questions