`total_memory_tracker.setOrRaiseHardLimit(...);` in `ConfigReloader` callback (see `Server.cpp`).
{
        parent.store(elem, std::memory_order_relaxed);
    }
    MemoryTracker * getParent()
    {
        return parent.load(std::memory_order_relaxed);
    }
    
    void setMetric(CurrentMetrics::Metric metric_)
    {
        metric = metric_;
    }
    void setDescription(const char * description)
    {
        description_ptr.store(description, std::memory_order_relaxed);
    }
    
    void resetCounters();
    
    void reset();
    
    void set(Int64 to);
    
    void logPeakMemoryUsage() const;
    
    struct BlockerInThread
    {
    private:
        BlockerInThread(const BlockerInThread &) = delete;