1. Debugging at Scale

2. How to Debug At Scale Lesson 1: Don’t Test with small problems first
Try to reproduce big problems at small scale
In a big program, comment out parts, slowly add them back

3. How to Debug At Scale Lesson 2: Location of Bug != Location of Error
This code crashes on line 25
Where is the bug?

4. How to Debug At Scale Lesson 2: Location of Bug != Location of Error
Error prone code
Pointing to things (what is lifespan of thing?)
Deleting memory
Copying things (deep copy??)
What error prone code ran shortly before the bug?

5. How to Debug At Scale Lesson 2: Location of Bug != Location of Error
Finding your error
Run in debug mode so you know where you crash
Put in break points or print statements to see:
How far you get
If your data is still valid
Use binary search

6. How to Debug At Scale Lesson 3: Conditional Breakpoints
Ignore first X hits of breakpoint
Stop when code expression is true

7. How to Debug At Scale Lesson 4: Print It Out
Reading a log can be easier than using debugger
Print out
Entering a particular function
All parameters to each recursive call
All information about current loop iteration
Redirect output to a text file: myProgram.exe > output.txt

8. How to Debug At Scale Print It Out Tip Make a log function:
You can turn off: