https://github.com/teivah/100-go-mistakes

Source code of the 100 Go Mistakes book

100 Go Mistakes and How to Avoid Them

Source code of 100 Go Mistakes and How to Avoid Them.

Table of Contents

Chapter 1 - Introduction

Chapter 2 - Code and Project Organization

• 1 - Unintended variable shadowing
• 2 - Writing nested code
• 3 - Misusing init functions
• 4 - Always using getters and setters
• 5 - Interface pollution
• 6 - Interface on the producer side
• 7 - Returning interfaces
• 8 - any says nothing
• 9 - Being confused about when to use generics
• 10 - Not being aware of the possible problems with type embedding
• 11 - Not using the functional options pattern
• 12 - Project misorganization (project structure and package organization)
• 13 - Creating utility packages
• 14 - Ignoring package name collisions
• 15 - Missing code documentation
• 16 - Not using linters

Chapter 3 - Data Types

• 17 - Creating confusion with octal literals
• 18 - Neglecting integer overflows
• 19 - Not understanding floating-points
• 20 - Not understanding slice length and capacity
• 21 - Inefficient slice initialization
• 22 - Being confused about nil vs. empty slice
• 23 - Not properly checking if a slice is empty
• 24 - Not making slice copy correctly
• 25 - Unexpected side-effects using slice append
• 26 - Slice and memory leaks
• 27 - Inefficient map initialization
• 28 - Map and memory leaks
• 29 - Comparing values incorrectly

Chapter 4 - Control Structures

• 30 - Ignoring that elements are copied in range loops
• 31 - Ignoring how arguments are evaluated in range loops (channels and arrays)
• 32 - Ignoring the impacts of using pointer elements in range loops
• 33 - Making wrong assumptions during map iterations (ordering and map insert during iteration)
• 34 - Ignoring how the break statement work
• 35 - Using defer inside a loop

Chapter 5 - Strings

• 36 - Not understanding the concept of rune
• 37 - Inaccurate string iteration
• 38 - Misusing trim functions
• 39 - Under-optimized strings concatenation
• 40 - Useless string conversion
• 41 - Substring and memory leaks

Chapter 6 - Functions and Methods

• 42 - Not knowing which type of receiver to use
• 43 - Never using named result parameters
• 44 - Unintended side-effects with named result parameters
• 45 - Returning a nil receiver
• 46 - Using a filename as a function input
• 47 - Ignoring how defer arguments and receivers are evaluated

Chapter 7 - Error Management

• 48 - Panicking
• 49 - Ignoring when to wrap an error
• 50 - Comparing an error type inaccurately
• 51 - Comparing an error value inaccurately
• 52 - Handling an error twice
• 53 - Not handling an error
• 54 - Not handling defer errors

Chapter 8 - Concurrency: Foundations

• 55 - Mixing concurrency and parallelism
• 56 - Concurrency isn't always faster
• 57 - Being puzzled about when to use channels or mutexes
• 58 - Not understanding race problems (data races vs. race conditions and Go memory model)
• 59 - Not understanding the concurrency impacts of a workload type
• 60 - Misunderstanding Go contexts

Chapter 9 - Concurrency: Practice

• 61 - Propagating an inappropriate context
• 62 - Starting a goroutine without knowing when to stop it
• 63 - Not being careful with goroutines and loop variables
• 64 - Expecting a deterministic behavior using select and channels
• 65 - Not using notification channels
• 66 - Not using nil channels
• 67 - Being puzzled about a channel size
• 68 - Forgetting about possible side-effects with string formatting (etcd and dead-lock)
• 69 - Creating data races with append
• 70 - Using mutexes inaccurately with slices and maps
• 71 - Misusing sync.WaitGroup
• 72 - Forgetting about sync.Cond
• 73 - Not using errgroup
• 74 - Copying a sync type

Chapter 10 - Standard Library

• 75 - Providing a wrong time duration
• 76 - time.After and memory leak
• 77 - JSON handling common mistakes
  • Unexpected behavior because of type embedding
  • JSON and monotonic clock
  • Map of any
• 78 - SQL common mistakes
  • Forgetting that sql.Open doesn't necessarily establish connections to a DB
  • Forgetting about connections pooling
  • Not using prepared statements
  • Mishandling null values
  • Not handling rows iteration errors
• 79 - Not closing transient resources (HTTP body, sql.Rows, and os.File)
• 80 - Forgetting the return statement after replying to an HTTP request
• 81 - Using the default HTTP client and server

Chapter 11 - Testing

• 82 - Not categorizing tests (build tags and short mode)
• 83 - Not enabling the race flag
• 84 - Not using test execution modes (parallel and shuffle)
• 85 - Not using table-driven tests
• 86 - Sleeping in unit tests
• 87 - Not dealing with the time API efficiently
• 88 - Not using testing utility packages (httptest and iotest)
• 89 - Writing inaccurate benchmarks
  • Not resetting or pausing the timer
  • Making wrong assumptions about micro-benchmarks
  • Not being careful about compiler optimizations
  • Being fooled by the observer effect
• 90 - Not exploring all the Go testing features
  • Code coverage
  • Testing from a different package
  • Utility functions
  • Setup and teardown

Chapter 12 - Optimizations

• 91 - Not understanding CPU caches
  • CPU architecture
  • Cache line
  • Slice of structs vs. struct of slices
  • Predictability
  • Cache placement policy
• 92 - Writing concurrent code leading to false sharing
• 93 - Not taking into account instruction-level parallelism
• 94 - Not being aware of data alignment
• 95 - Not understanding stack vs. heap
• 96 - Not knowing how to reduce allocations
  • API change
  • Compiler optimizations
  • sync.Pool
• 97 - Not relying on inlining
• 98 - Not using Go diagnostics tooling (profiling and execution tracer)
• 99 - Not understanding how the GC works
• 100 - Not understanding the impacts of running Go inside of Docker and Kubernetes