https://clickhouse-test-reports.s3.yandex.net/18817/9049599e367bcccd809f45af138452f965b3303a/stress_test_(undefined)/test_run.txt.out.log
const String & session_id,
        Context & context,
        std::chrono::steady_clock::duration timeout,
        bool throw_if_not_found)
    {
        std::unique_lock lock(mutex);
        auto & user_name = context.client_info.current_user;
        if (user_name.empty())
            throw Exception("Empty user name.", ErrorCodes::LOGICAL_ERROR);
        Key key(user_name, session_id);
        auto it = sessions.find(key);
        if (it == sessions.end())
        {
            if (throw_if_not_found)
                throw Exception("Session not found.", ErrorCodes::SESSION_NOT_FOUND);
            
            it = sessions.insert(std::make_pair(key, std::make_shared<NamedSession>(key, context, timeout, *this))).first;
        }
        else if (it->second->key.first != context.client_info.current_user)
        {
            throw Exception("Session belongs to a different user", ErrorCodes::SESSION_IS_LOCKED);
        }
        
        const auto & session = it->second;
        if (!session.unique())
            throw Exception("Session is locked by a concurrent client.", ErrorCodes::SESSION_IS_LOCKED);
        session->context.client_info = context.client_info;
        return session;
    }
    void releaseSession(NamedSession & session)