Peas in a pod.

What this C++ concurrency code-review question tests

This is an easy concurrency question that asks you to identify which class of threading hazard a given code pattern is designed to prevent. It's a reading-comprehension check: you need to recognize the symptom (data race, deadlock, race condition, etc.) and match it to the safeguard in place.

Questions like this appear in phone screens and early-round interviews at firms that build multi-threaded systems. They test whether you understand the practical purpose of concurrency primitives—not just their syntax, but when and why you'd actually use them. A strong answer names the specific hazard, explains the scenario where it could occur without the protection, and traces how the code blocks that scenario.

• Race conditions and data races
• Mutual exclusion and locks
• Ordering and happens-before relationships
• Common pitfalls in shared-memory concurrency