Debugging- for rigtige programmører

1. Debugging using printf()
peter@makholm.net

7. Four Basic Rules!
●
Use a version control system!
●
Understand your code
●
Understand your problem
●
Think before typing!

8. To printf or not to printf
●
Build time restrictions
●
Environment restrictions
●
Use your language
●
Use your editor

9. Print to where?
●
stderr
●
stdout
●
syslog
●
/var/log/app/errors.log
●
strace(1)

10. What to print
●
Timestamp
●
Location in code
●
Process or request ID
●
What you are dumping

11. Pitfalls
●
changes errno
●
changes buffering
●
can block
●
additional file descriptors

12. Post Mortem
●
Write tests
●
Add assertions
●
Add logging
●
Go to the pub