负载均衡测量函数 - 日志服务

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`(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。	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
`load_matrix`	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

cluster_id	balance
G1	0.5