`total_memory_tracker.setOrRaiseHardLimit(...);` in `ConfigReloader` callback (see `Server.cpp`).
{
    if (metric != CurrentMetrics::end())
        CurrentMetrics::sub(metric, amount.load(std::memory_order_relaxed));
    resetCounters();
}
void MemoryTracker::set(Int64 to)
{
    amount.store(to, std::memory_order_relaxed);
    updatePeak(to);
}
void MemoryTracker::setOrRaiseHardLimit(Int64 value)
{
    
    Int64 old_value = hard_limit.load(std::memory_order_relaxed);
    while (old_value < value && !hard_limit.compare_exchange_weak(old_value, value))
        ;
}
void MemoryTracker::setOrRaiseProfilerLimit(Int64 value)
{
    Int64 old_value = profiler_limit.load(std::memory_order_relaxed);
    while (old_value < value && !profiler_limit.compare_exchange_weak(old_value, value))
        ;
}