100 Go Mistakes and How to Avoid Them

100 Go Mistakes
contents
preface
acknowledgments
about this book
Who should read this book
How this book is organized: A roadmap
About the code
liveBook discussion forum
about the author
about the cover illustration
1 Go: Simple to learn but hard to master
1.1 Go outline
1.2 Simple doesn’t mean easy
1.3 100 Go mistakes
1.3.1 Bugs
1.3.2 Needless complexity
1.3.3 Weaker readability
1.3.4 Suboptimal or unidiomatic organization
1.3.5 Lack of API convenience
1.3.6 Under-optimized code
1.3.7 Lack of productivity
Summary
2 Code and project organization
2.1 #1: Unintended variable shadowing
2.2 #2: Unnecessary nested code
2.3 #3: Misusing init functions
2.3.1 Concepts
2.3.2 When to use init functions
2.4 #4: Overusing getters and setters
2.5 #5: Interface pollution
2.5.1 Concepts
2.5.2 When to use interfaces
2.5.3 Interface pollution
2.6 #6: Interface on the producer side
2.7 #7: Returning interfaces
2.8 #8: any says nothing
2.9 #9: Being confused about when to use generics
2.9.1 Concepts
2.9.2 Common uses and misuses
2.10 #10: Not being aware of the possible problems with type embedding
2.11 #11: Not using the functional options pattern
2.11.1 Config struct
2.11.2 Builder pattern
2.11.3 Functional options pattern
2.12 #12: Project misorganization
2.12.1 Project structure
2.12.2 Package organization
2.13 #13: Creating utility packages
2.14 #14: Ignoring package name collisions
2.15 #15: Missing code documentation
2.16 #16: Not using linters
Summary
3 Data types
3.1 #17: Creating confusion with octal literals
3.2 #18: Neglecting integer overflows
3.2.1 Concepts
3.2.2 Detecting integer overflow when incrementing
3.2.3 Detecting integer overflows during addition
3.2.4 Detecting an integer overflow during multiplication
3.3 #19: Not understanding floating points
3.4 #20: Not understanding slice length and capacity
3.5 #21: Inefficient slice initialization
3.6 #22: Being confused about nil vs. empty slices
3.7 #23: Not properly checking if a slice is empty
3.8 #24: Not making slice copies correctly
3.9 #25: Unexpected side effects using slice append
3.10 #26: Slices and memory leaks
3.10.1 Leaking capacity
3.10.2 Slice and pointers
3.11 #27: Inefficient map initialization
3.11.1 Concepts
3.11.2 Initialization
3.12 #28: Maps and memory leaks
3.13 #29: Comparing values incorrectly
Summary
4 Control structures
4.1 #30: Ignoring the fact that elements are copied in range loops
4.1.1 Concepts
4.1.2 Value copy
4.2 #31: Ignoring how arguments are evaluated in range loops
4.2.1 Channels
4.2.2 Array
4.3 #32: Ignoring the impact of using pointer elements in range loops
4.4 #33: Making wrong assumptions during map iterations
4.4.1 Ordering
4.4.2 Map insert during iteration
4.5 #34: Ignoring how the break statement works
4.6 #35: Using defer inside a loop
Summary
5 Strings
5.1 #36: Not understanding the concept of a rune
5.2 #37: Inaccurate string iteration
5.3 #38: Misusing trim functions
5.4 #39: Under-optimized string concatenation
5.5 #40: Useless string conversions
5.6 #41: Substrings and memory leaks
Summary
6 Functions and methods
6.1 #42: Not knowing which type of receiver to use
6.2 #43: Never using named result parameters
6.3 #44: Unintended side effects with named result parameters
6.4 #45: Returning a nil receiver
6.5 #46: Using a filename as a function input
6.6 #47: Ignoring how defer arguments and receivers are evaluated
6.6.1 Argument evaluation
6.6.2 Pointer and value receivers
Summary
7 Error management
7.1 #48: Panicking
7.2 #49: Ignoring when to wrap an error
7.3 #50: Checking an error type inaccurately
7.4 #51: Checking an error value inaccurately
7.5 #52: Handling an error twice
7.6 #53: Not handling an error
7.7 #54: Not handling defer errors
Summary
8 Concurrency: Foundations
8.1 #55: Mixing up concurrency and parallelism
8.2 #56: Thinking concurrency is always faster
8.2.1 Go scheduling
8.2.2 Parallel merge sort
8.3 #57: Being puzzled about when to use channels or mutexes
8.4 #58: Not understanding race problems
8.4.1 Data races vs. race conditions
8.4.2 The Go memory model
8.5 #59: Not understanding the concurrency impacts of a workload type
8.6 #60: Misunderstanding Go contexts
8.6.1 Deadline
8.6.2 Cancellation signals
8.6.3 Context values
8.6.4 Catching a context cancellation
Summary
9 Concurrency: Practice
9.1 #61: Propagating an inappropriate context
9.2 #62: Starting a goroutine without knowing when to stop it
9.3 #63: Not being careful with goroutines and loop variables
9.4 #64: Expecting deterministic behavior using select and channels
9.5 #65: Not using notification channels
9.6 #66: Not using nil channels
9.7 #67: Being puzzled about channel size
9.8 #68: Forgetting about possible side effects with string formatting
9.8.1 etcd data race
9.8.2 Deadlock
9.9 #69: Creating data races with append
9.10 #70: Using mutexes inaccurately with slices and maps
9.11 #71: Misusing sync.WaitGroup
9.12 #72: Forgetting about sync.Cond
9.13 #73: Not using errgroup
9.14 #74: Copying a sync type
Summary
10 The standard library
10.1 #75: Providing a wrong time duration
10.2 #76: time.After and memory leaks
10.3 #77: Common JSON-handling mistakes
10.3.1 Unexpected behavior due to type embedding
10.3.2 JSON and the monotonic clock
10.3.3 Map of any
10.4 #78: Common SQL mistakes
10.4.1 Forgetting that sql.Open doesn’t necessarily establish connections to a database
10.4.2 Forgetting about connections pooling
10.4.3 Not using prepared statements
10.4.4 Mishandling null values
10.4.5 Not handling row iteration errors
10.5 #79: Not closing transient resources
10.5.1 HTTP body
10.5.2 sql.Rows
10.5.3 os.File
10.6 #80: Forgetting the return statement after replying to an HTTP request
10.7 #81: Using the default HTTP client and server
10.7.1 HTTP client
10.7.2 HTTP server
Summary
11 Testing
11.1 #82: Not categorizing tests
11.1.1 Build tags
11.1.2 Environment variables
11.1.3 Short mode
11.2 #83: Not enabling the -race flag
11.3 #84: Not using test execution modes
11.3.1 The parallel flag
11.3.2 The -shuffle flag
11.4 #85: Not using table-driven tests
11.5 #86: Sleeping in unit tests
11.6 #87: Not dealing with the time API efficiently
11.7 #88: Not using testing utility packages
11.7.1 The httptest package
11.7.2 The iotest package
11.8 #89: Writing inaccurate benchmarks
11.8.1 Not resetting or pausing the timer
11.8.2 Making wrong assumptions about micro-benchmarks
11.8.3 Not being careful about compiler optimizations
11.8.4 Being fooled by the observer effect
11.9 #90: Not exploring all the Go testing features
11.9.1 Code coverage
11.9.2 Testing from a different package
11.9.3 Utility functions
11.9.4 Setup and teardown
Summary
12 Optimizations
12.1 #91: Not understanding CPU caches
12.1.1 CPU architecture
12.1.2 Cache line
12.1.3 Slice of structs vs. struct of slices
12.1.4 Predictability
12.1.5 Cache placement policy
12.2 #92: Writing concurrent code that leads to false sharing
12.3 #93: Not taking into account instruction-level parallelism
12.4 #94: Not being aware of data alignment
12.5 #95: Not understanding stack vs. heap
12.5.1 Stack vs. heap
12.5.2 Escape analysis
12.6 #96: Not knowing how to reduce allocations
12.6.1 API changes
12.6.2 Compiler optimizations
12.6.3 sync.Pool
12.7 #97: Not relying on inlining
12.8 #98: Not using Go diagnostics tooling
12.8.1 Profiling
12.8.2 Execution tracer
12.9 #99: Not understanding how the GC works
12.9.1 Concepts
12.9.2 Examples
12.10 #100: Not understanding the impacts of running Go in Docker and Kubernetes
Summary
Final words
index
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J
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