CppCon 2026

In the C++ world, it is often assumed that proper object lifetime management ensures a memory footprint that scales with an application’s actual needs. However, long-running systems are frequently sabotaged by heap pinning: a phenomenon in which Resident Set Size (RSS) refuses to shrink even after significant deallocations. This results in a critical, 'invisible' overhead that defies standard leak-detection tools and can lead to system thrashing and even Out Of Memory (OOM) kills.

Heap pinning occurs when long-lived allocations are interleaved with transient ones, creating a structural barrier that prevents the underlying allocator from releasing memory back to the system. A single persistent allocation can 'pin' an entire block of physical memory, forcing the OS to keep it mapped even if the surrounding space is empty. Consequently, the process footprint reflects historical peak usage rather than the current live state.

In this talk, we will bridge the disconnect between C++ deallocations and physical memory reclamation. You will learn to use allocator-aware objects and std::pmr resources to eliminate pinning by strategically segregating allocations based on their expected lifetimes. We will also demonstrate how to diagnose these 'ghost' overheads when traditional heap profilers fall short. You’ll leave the session equipped to identify and resolve these fragmentation traps, ensuring your application’s memory footprint finally stays proportional to its actual state.