问有必要锁定读取对象吗？

EN

class Logger {
    std::mutex m_mutex;
    std::list<std::string> m_queLogs;
public:

    int info(std::string zLog) {
        std::lock_guard<std::mutex> lk(m_mutex);

        m_queLogs.push_back(std::move(zLog));
        ...
    }

    std::string popLog() { //!!!!! Do I need to add a lock_guard here?
        if (m_queLogs.size() == 0)
            return "";

        auto zLog = m_queLogs.front();
        m_queLogs.pop_front();

        return zLog;
    }
}

// Thread 1
int TcpComm::OnRecv(int opCode, char* buf) {

    switch (opCode) {
    case CODE_LOG:                      // generated nearly Real-time 
        Logger::instance()->info(buf);

        break;
        ...
    }
    ...
}

// Thread 2
void MonitorThread(LPVOID lpvoid) {
    while (1) {
        Sleep(60 * 1000);               // generated some times.

        Logger::instance()->info(" ---- monitor signal --- ");
        ...
    }
}


// UI Thread
void CLogView::OnTimer(UINT_PTR nIDEvent)
{
    // every 500 milisecond.
    auto zLog = Logger::instance()->popLog();
    CString strLog = convert_utf8_to_cstring(zLog);

    m_ctrLogView.AppendString(strLog);
}