RCU, Epochs, and Memory Reclamation
Removing an object from a shared structure does not prove that no reader can still reach it. Reclamation determines when its storage may be reused.
Planned model
Track readers, retired nodes, epochs, grace periods, and reclamation. Contrast reference counting, hazard pointers, epochs, and read-copy-update.
Questions
- What event proves that every old reader has finished?
- How can a stalled participant delay reclamation?
- Which problem is the ABA pattern exposing?
Exercise
Specify a safe lifecycle for removing and eventually freeing a node that lock-free readers may already hold.