What pointer?

Understanding hazard pointers in concurrent C++

This is an easy conceptual question on memory reclamation in lock-free concurrent systems. It tests whether you understand a practical solution to the ABA problem and safe deallocation in multithreaded code where readers may hold references to objects without locks.

Hazard pointers are a mechanism that lets threads announce which pointers they are actively using, allowing other threads to defer deletion of those objects until all hazard claims are cleared. The question probes your grasp of how this coordination works at a fundamental level—what invariants must be maintained, what data structures are involved, and how the pattern prevents use-after-free bugs in lock-free designs.

• Lock-free memory reclamation strategies
• Reader-writer safety without mutual exclusion
• The ABA problem and its solutions
• Epoch-based and pointer-scanning approaches