@Override
    public int poolSize() {
        return (int) connectionManagers.values().stream()
            .mapToInt(man -> man.counter.get())
            .filter(c -> c == 0L)
            .count();
    }
Configuration parameter that controls if a request for a new connection
should be queued until one becomes available or if it should cause an
exception to be thrown if no connection is available.
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/component/connectionpool/SingletonConnectionPoolComponent.java