Tip 12: Check Assumptions

DTrace lets you check your assumptions, usually with short one-liners. Try to get into the habit of not only being aware of the assumptions you are making but also checking them where possible with DTrace.

For example, you might assume that operating system statistics such as network interface statistics are always correct. This isn’t true: Bugs happen. DTrace can be used to calculate statistics from different points in the system to double-check their accuracy. (This has unearthed statistics bugs on more than one occasion.)