Quotes and Notes from 'Becoming a Better Programmer' - Chapters 9-10

From O'Reilly e-book:
Becoming a Better Programmer by Pete Goodliffe

Chapter 9 - Expect the Unexpected

Any function you call may not work as you expect.
• If you are lucky, it will return an error code to signal this. (p.69)

p.70:

•  understand basic concurrency principles
• Understand mechanisms to reliably and quickly pass messages between thread contexts without introducing race conditions or blocking the threads unnecessarily
•  Shutdown:
• how to bring the code to a graceful halt without leaking resources, locking up, or crashing
• especially hard in a multithreaded system
• don't leave one object attempting to use or return to another that has been deleted

Chapter 10 - Bug Hunting

• Lay Traps: Add assertions or tests to verify the system invariants—the facts that must hold for the state to be correct. (p.78)
• Binary Chop: (p.78)
  
• Work out the start of a chain of events.
• Work out the end
• Check middle point
• if good, then start to middle is good, so check midpoint of here to end
• if bad, then check midpoint of start to this point
• Software Archaeology
• Look thru your version control to find the last time this bug didn't exist
• Binary chop through time to find where bug was introduced
• Use a code coverage tool to inspect how much of your code is actually covered by tests. (p.79)
• Once you find the bug:
• Write a simple test that demonstrates the bug.
• Add it to the test suite before you fix the code.
• Use the test to:
• prove bug is fixed
• test to prevent bug from reoccurring
•  Analyze/look for related bugs
• Are there more bugs in the section where you found this one?
• Was bug in a repeated code pattern that's used elsewhere?
• Note in which parts of the code you're finding more bugs.
• Part of code that's used most often?
• Weakness in that particular section of the software? 
• Non-Reproducible Bugs
• Keep records that may eventually help you come up with theories you can test to possibly find the cause.
• Add more assertions and log statements -- preferably into your beta or release builds.
• Automate a test farm to run long-running soak tests.
• Common situations leading to hard-to-reproduce bugs:
• Threads
• "Heisenbugs" - disappear when you add log statements
• Network interacation
• Speed to access database, disk, other storage can vary
• Memory corruption
• Global variables