Are they always like this?

Understanding lock-free guarantees in atomic operations

This is an easy concurrency question that tests whether you understand the difference between an atomic operation and a lock-free operation in C++. It is a foundational concept for any engineer writing multi-threaded code, especially in performance-critical systems where latency matters.

The question probes whether you know that atomicity and lock-freedom are separate properties. A candidate should be able to explain what guarantees the standard library provides, how to query those guarantees at runtime or compile time, and why the distinction matters in practice. This is the kind of conceptual checkpoint that interviewers use to separate engineers who have thought carefully about concurrency from those who treat atomics as a black box.

• The definition of lock-free operations and their performance implications
• How to check lock-free status using standard library utilities
• Platform-dependent behavior of atomic types
• Trade-offs between atomicity, lock-freedom, and portability