sync.OnceFunc, OnceValue, OnceValues: When Each Beats sync.Once

📰 Dev.to · Gabriel Anhaia

Learn when to use sync.OnceFunc, OnceValue, and OnceValues over sync.Once in Go 1.21 for cleaner and more efficient initialization patterns

intermediate Published 7 May 2026
Action Steps
  1. Use sync.OnceFunc when you need to initialize a function with a return value
  2. Apply sync.OnceValue for simple initialization with a single value
  3. Utilize sync.OnceValues when dealing with multiple values that need to be initialized concurrently
  4. Avoid the error-return trap by handling errors properly in your initialization functions
  5. Test your initialization patterns with different concurrency scenarios to ensure correctness
Who Needs to Know This

Go developers and engineers who want to improve their concurrency handling and initialization patterns will benefit from this knowledge, as it helps to avoid the error-return trap and write more efficient code

Key Insight

💡 Choose the right sync primitive based on your initialization needs to write cleaner and more efficient Go code

Share This
🚀 Improve your Go concurrency skills with sync.OnceFunc, OnceValue, and OnceValues! 🚀

Full Article

Go 1.21's sync.OnceFunc / OnceValue / OnceValues vs sync.Once. When each is the cleanest, the error-return trap, init patterns.
Read full article → ← Back to Reads

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