/*
     * No lock is required because the session array is fixed size, but it may contain inactive
     * entries. We must review any active session, so insert a read barrier after reading the active
     * session count. That way, no matter what sessions come or go, we'll check the slots for all of
     * the sessions that could have been active when we started our check.
     */
    WT_ORDERED_READ(session_cnt, conn->session_cnt);
    /*
     * We need to order the read of the connection generation before the read of the session
     * generation. If the session generation read is ordered before the connection generation read
     * it could read an earlier session generation value. This would then violate the acquisition
     * semantics and could result in us reading 0 for the session generation when it is non-zero.
     */
    WT_ORDERED_READ(oldest, conn->generations[which]);