Comment by andrewaylett

Let me see if I can understand this properly:

There's a linear buffer of pages, most of which come from the pool. It's not clear to me under what conditions these are returned to the pool? Is it when the specific session terminates?

When a non-standard page reaches the point of being recycled, it'll instead be re-added to the list but with a standard size. That effectively leaks the extra space above the standard size. But when the buffer is released (because the session ends?) the pool is also released, which releases all the standard sized pages but leaks the custom-sized ones?

Which suggests that the issue may be even rarer than it initially looked to me: I tend to open a small number of sessions and then use them continuously, rather than starting new sessions during the lifetime of the process. If I never terminated a session, I would never fully leak the memory?