When to Use Mutex vs Channels for Synchronization

Problem Statement

A Staff Engineer at Stripe asks: "We have a high-frequency payment counter that increments millions of times per second. Should we use a Mutex, Channels, or Atomics? Explain your reasoning and benchmark the difference."

The Go Proverb

"Share memory by communicating, don't communicate by sharing memory."

But this doesn't mean channels are always the right choice.

Decision Framework

Use Case	Best Choice	Reason
Simple counter	atomic.AddInt64	Hardware instruction, fastest
Protecting complex state	sync.Mutex	Clear ownership semantics
Coordinating goroutines	Channels	Communication pattern
Read-heavy, write-rare	sync.RWMutex	Multiple concurrent readers

Benchmark Implementation

Typical Results

Conclusion

For the payment counter scenario: Use atomic operations. They're ~4x faster than Mutex and ~18x faster than channels for simple increments.

Follow-up Questions

1. When would channels be the better choice despite being slower?
2. What is "False Sharing" and how does it affect atomic counters?
3. How do you implement a lock-free data structure?