der," tips for help desks, and closing remarks.
There are lots of good points here. One that particularly stands out is "quit thinking and look." Too many try to "fix" things based on a guess instead of gathering and observing data to prove or disprove a hypothesis. Another principle that stands out is "if you didn't fix it, it ain't fixed;" there are several vendors I'd like to give that advice to. The whole "stimulate the failure, don't simulate the failure" discussion is not as clearly explained as most of the book, but it's a valid point worth understanding.
I particularly appreciated Agans' discussions on intermittent problems (particularly in "Make it Fail"). Intermittent problems are usually the hardest to deal with, and the author gives straightforward advice on how to deal with them. One odd thing is that although he mentions Heisenberg, he never mentions the term "Heisenbug," a common jargon term in software development (a Heisenbug is a bug that disappears or alters its behavior when one attempts to probe or isolate it). At least a note would've been appropriate.
The back cover includes a number of endorsements, including one from somebody named Rob Malda. But don't worry, the book's good anyway :-).
It's important to note that this is a book on fundamentals, and different than most other books related to debugging. There are many other books on debugging, such as Richard Stallman et al's Debugging with GDB: The GNU Source-Level Debugger. But these other texts usually concentrate primarily on a specific technology and/or on explaining tool commands. A few (like Norman Matloff's guide to faster, less-frustrating debugging ) have a few more general suggestions on debugging, but are nothing like Agans' book. There are many books on testing, like Boris Beizer's Software Testing Techniques, but they tend to emphasize how to create tests to detect bugs, and less on how to fix a bug once it's been detected. Agans' book concentrates on the big picture on debugging; these other books are complementary to it.
Debugging has an accompanying website at debuggingrules.com, where you can find various little extras and links to related information. In particular, the website has an amusing poster of the nine rules you can download and print.
No book's perfect, so here are my gripes and wishes:
- The sub-rules are really important for understanding the rules, but there's no "master list" in the book or website that shows all the rules and sub-rules on one page. The end of the chapter about a given rule summarizes the sub-rules for that one rule, but it'd sure be easier to have them all in one place. So, print out the list of sub-rules above after you've read the book.
- The book left me wishing for more detailed suggestions about specific common technology. This is probably unfair, since the author is trying to give timeless advice rather than a "how to use tool X" tutorial. But it'd be very useful to give good general advice, specific suggestions, and examples of what approaches to take for common types of tools (like symbolic debuggers, digital logic probes, etc.), specific widely-used tools (like ddd on gdb), and common problems. Even after the specific tools are gone, such advice can help you use later ones. A little of this is hinted at in the "know your tools" section, but I'd like to have seen much more of it. Vendors often crow about what their tools can do, but rarely explain their weaknesses or how to apply them in a broader context.
- There's probably a need for another book that takes the same rules, but broadens them to solving arbitrary problems. Frankly, the rules apply to many situations beyond computing, but the war stories are far too technical for the non-computer person to understand.
But as you can tell, I think this is a great book. In some sense, what it says is "obvious," but it's only obvious as all fundamentals are obvious. Many sports teams know the fundamentals, but fail to consistently apply them - and fail because of it. Novices need to learn the fundamentals, and pros need occasional reminders of