Introduction

Go’s sync package contains the building blocks for safe concurrent programming. When multiple goroutines access shared data, you need synchronization to prevent race conditions and data corruption.

The sync package provides several key primitives:

• Mutex: Mutual exclusion locks for protecting shared resources
• RWMutex: Reader-writer locks for read-heavy workloads
• WaitGroup: Waiting for a collection of goroutines to finish
• Once: Ensuring a function runs exactly once
• Cond: Condition variables for complex coordination
• Pool: Object pools for reducing garbage collection pressure

When to Use Sync Primitives

Go’s philosophy is “Don’t communicate by sharing memory; share memory by communicating.” Channels are often the right choice for goroutine coordination. However, sync primitives are essential when:

• Protecting shared state that multiple goroutines access
• Implementing low-level concurrent data structures
• Optimizing performance-critical code paths
• Building higher-level synchronization abstractions

Common Pitfalls

Synchronization bugs are notoriously difficult to debug. Common mistakes include:

• Deadlocks: Goroutines waiting for each other indefinitely
• Race conditions: Unsynchronized access to shared data
• Lock contention: Too many goroutines competing for the same lock
• Forgetting to unlock: Causing permanent blocking

This guide covers each primitive in detail, with practical examples and guidance on when to use each approach.