Compaction of memory in long running systems has always been important. The latency of compaction increases in today’s systems with high memory demands and large heaps. To deal with this problem, we present a lock-free protocol allowing for copying concurrent with the application running, which reduces the latencies of compaction radically. It pro- vides theoretical progress guarantees for copying and appli- cation threads without making it practically infeasible, with performance overheads of 20% on average. The algorithm paves way for a future lock-free Garbage Collector.