host is done with the shared pool. The pool is disposed once no host holds
it any more — including when host never retained it (a teardown after a
failed init), so a pool nobody else holds is still cleaned up. Returns whether
this call disposed the pool.
hostis done with the shared pool. The pool is disposed once no host holds it any more — including whenhostnever retained it (a teardown after a failed init), so a pool nobody else holds is still cleaned up. Returns whether this call disposed the pool.