在执行操作实现负载均衡前，需要准确衡量分布式系统负载均衡状况。本文介绍负载均衡测量函数的基本语法和示例。
背景信息
负载均衡测量函数示例的日志包含六个字段索引（集群ID、服务器ID、时间、CPU负载、内存负载和网络带宽负载）。更多信息，请参见创建索引。
日志样例如下：
{"cluster_id":"C001","cpu_load":"0.1","network_load":"0.6","ram_load":"0.7","server_id":"S001","time_period":"2024-01-01 00:00:00"} {"cluster_id":"C001","cpu_load":"0.2","network_load":"0.5","ram_load":"0.8","server_id":"S002","time_period":"2024-01-01 00:01:00"} {"cluster_id":"C001","cpu_load":"0.1","network_load":"0.6","ram_load":"0.7","server_id":"S001","time_period":"2024-01-01 00:02:00"} {"cluster_id":"C001","cpu_load":"0.2","network_load":"0.5","ram_load":"0.8","server_id":"S002","time_period":"2024-01-01 00:03:00"} {"cluster_id":"C001","cpu_load":"0.1","network_load":"0.6","ram_load":"0.7","server_id":"S001","time_period":"2024-01-01 00:04:00"} {"cluster_id":"C001","cpu_load":"0.2","network_load":"0.5","ram_load":"0.8","server_id":"S002","time_period":"2024-01-01 00:05:00"} {"cluster_id":"C001","cpu_load":"0.1","network_load":"0.6","ram_load":"0.7","server_id":"S001","time_period":"2024-01-01 00:06:00"} {"cluster_id":"C001","cpu_load":"0.2","network_load":"0.5","ram_load":"0.8","server_id":"S002","time_period":"2024-01-01 00:07:00"} {"cluster_id":"C001","cpu_load":"0.1","network_load":"0.6","ram_load":"0.7","server_id":"S001","time_period":"2024-01-01 00:08:00"} {"cluster_id":"C001","cpu_load":"0.2","network_load":"0.5","ram_load":"0.8","server_id":"S002","time_period":"2024-01-01 00:09:00"}
负载均衡度函数列表
函数名称 | 语法 | 说明 | 返回值类型 |
how_balanced函数 | how_balanced(array(array(double)) load_matrix) | 结合array_agg函数，测量分布式系统负载均衡度。返回值表示负载均衡的程度，范围在 | double |
how_balanced函数
结合array_agg函数，测量分布式系统负载均衡度。
double how_balanced(array(array(double)) load_matrix)参数 | 说明 |
| 一个负载矩阵，每一行代表了单个服务器的负载时间序列向量。 |
使用示例
查询和分析语句
* | with server_time_series as ( select cluster_id, server_id, array_agg(to_unixtime(date_parse(time_period, '%Y-%m-%d %H:%i:%s'))) as time_periods, array_agg(cpu_load + ram_load + network_load) as metric_values from log where time_period >= '2024-01-01 00:00:00' and time_period < '2024-01-02 00:00:00' group by cluster_id, server_id ), imputed_server_series as ( select cluster_id, server_id, ts_fill_missing( time_periods, metric_values, to_unixtime(date_parse('2024-01-01 00:00:00', '%Y-%m-%d %H:%i:%s')), to_unixtime(date_parse('2024-01-02 00:00:00', '%Y-%m-%d %H:%i:%s')), '1 minute', 'value=0') as imputed_time_series from server_time_series ) select cluster_id, how_balanced(array_agg(imputed_time_series[2])) as balance from imputed_server_series group by cluster_id返回结果
balance表示负载均衡的程度，范围在(0,1]之间。数值越接近1，表示负载越均衡，其中1表示完全平衡状态。cluster_id
balance
G1
0.5