Simply display zero if it's less or equals to 0.
void addThreadIdToList(String const & host, UInt64 thread_id);
    void updateThreadEventData(HostToThreadTimesMap & new_thread_data, UInt64 elapsed_time);
private:
    size_t getUsedThreadsCount() const;
    double getCPUUsage() const;
    struct MemoryUsage
    {
        UInt64 total = 0;
        UInt64 max   = 0;
    };
    MemoryUsage getMemoryUsage() const;
    
    
    bool show_progress_bar = false;
    
    
    size_t written_progress_chars = 0;
    
    
    Progress progress;
    
    Stopwatch watch;
    bool write_progress_on_update = false;
    std::unordered_map<String, double> host_cpu_usage;
    HostToThreadTimesMap thread_data;
};
}