Go Optimization Guide

What do you mean? Pool content can't be GCed , because there are references to it: pool itself.

What people do is what this article suggested, pool.Get/pool.Put, which makes it only grow in size even if load profile changes. App literally accumulated now unwanted garbage in pool and no app I have seen made and attempt to GC it.

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

From the sync.Pool documentation:

> If the Pool holds the only reference when this happens, the item might be deallocated.

Conceptually, the pool is holding a weak pointer to the items inside it. The GC is free to clean them up if it wants to, when it gets triggered.