# Sync Primitives (Go)

> sync.Mutex, RWMutex, Once, Pool, Map, Cond, atomic operations

- 22 interview questions
- Mid-Level
- [Interview Questions: Go](https://sharpskill.dev/en/technologies/go/interview-questions.md)

## 1. What is a sync.Mutex in Go?

**Answer**

A sync.Mutex (mutual exclusion lock) is a synchronization primitive that ensures only one goroutine can access a critical section at a time. Calling Lock blocks until the mutex is available, and Unlock releases it for other goroutines. Use it to protect concurrent access to shared data.

## 2. What happens if we forget to call Unlock after Lock on a sync.Mutex?

**Answer**

Forgetting Unlock creates a potential deadlock as other goroutines will wait indefinitely to acquire the mutex. The best practice is to use defer to ensure Unlock will be called even in case of panic. Always pair Lock and Unlock in the same scope to avoid lock leaks.

## 3. What is the main difference between sync.Mutex and sync.RWMutex?

**Answer**

The sync.RWMutex allows multiple concurrent reads via RLock but only one exclusive write via Lock. This improves performance for read-heavy scenarios as readers don't block each other. Use RWMutex when reads are frequent and writes are rare.

## 19 more questions available

- Why use defer with Unlock on a sync.Mutex?
- When to prefer sync.RWMutex over sync.Mutex?

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