Exception: PG::PoolExhausted
Overview
Pool-side error (no SQLSTATE): raised by PG::Pool#checkout when the pool stays empty past the checkout timeout. Subclasses Error so callers can ‘rescue PG::PoolExhausted` or the broader `rescue PG::Error`. (Raising namespaced errors from instance methods became viable with matz/spinel#1041; before that, checkout surfaced exhaustion as a sentinel nil-equivalent Connection.)