`total_memory_tracker.setOrRaiseHardLimit(...);` in `ConfigReloader` callback (see `Server.cpp`).
{
        return amount.load(std::memory_order_relaxed);
    }
    Int64 getPeak() const
    {
        return peak.load(std::memory_order_relaxed);
    }
    /** Set limit if it was not set.
      * Otherwise, set limit to new value, if new value is greater than previous limit.
      */
    void setOrRaiseHardLimit(Int64 value);
    void setOrRaiseProfilerLimit(Int64 value);
    void setFaultProbability(double value)
    {
        fault_probability = value;
    }
    void setSampleProbability(double value)
    {
        sample_probability = value;
    }
    void setProfilerStep(Int64 value)
    {
        profiler_step = value;
    }
    
    
    void setParent(MemoryTracker * elem)