sync.Pool uses weak references for this purpose. The pool does delay GC, and if your pooled objects have pointers, those are real and can be a problem. If your app never decreases the pool size, you've probably reached a stable equilibrium with usage, or your usage fits a pattern that GC has trouble with. If Go truly cannot GC your pooled objects, you probably have a memory leak. E.g. if you have Nodes in a graph with pointers to each other in the pool, and some root pointer to anything in the pool, that's a memory leak