Readmodifywrite
Read-modify-write (RMW) refers to an operation that reads a memory location, computes a new value from the read data, and writes the result back, ideally as an indivisible action from the perspective of other threads. Many computer architectures provide atomic RMW instructions that perform the read, compute, and write in a single, uninterruptible step, guaranteeing that concurrent operations do not observe intermediate states.
Common atomic RMW operations include fetch-and-add, test-and-set, compare-and-swap (CAS), and exchange (swap). These primitives enable lock-free
Practical use cases include implementing atomic counters, pointer updates in lock-free linked structures, reference counting, and
Challenges and considerations include memory ordering and visibility across cores, which may require fences or stronger
See also: atomic operations, memory ordering, lock-free programming, ABA problem.