負載平衡測量函數 - Simple Log Service

在執行操作實現負載平衡前，需要準確衡量分布式系統負載平衡狀況。本文介紹負載平衡測量函數的基本文法和樣本。

背景資訊

負載平衡測量函數樣本的日誌包含六個欄位索引（叢集ID、伺服器ID、時間、CPU負載、記憶體負載和網路頻寬負載）。更多資訊，請參見建立索引。

日誌範例如下：

{"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"}

負載平衡度函數列表

函數名稱	文法	說明	傳回值類型
how_balanced函數	how_balanced(array(array(double)) load_matrix)	結合array_agg函數，測量分布式系統負載平衡度。傳回值表示負載平衡的程度，範圍在`(0,1]`之間。數值越接近1，表示負載越均衡，其中1表示完全平衡狀態。	double

how_balanced函數

結合array_agg函數，測量分布式系統負載平衡度。

double how_balanced(array(array(double)) load_matrix)

參數	說明
`load_matrix`	一個負載矩陣，每一行代表了單個伺服器的負載時間序列向量。

使用樣本

查詢和分析語句

* | 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

返回結果
balance表示負載平衡的程度，範圍在(0,1]之間。數值越接近1，表示負載越均衡，其中1表示完全平衡狀態。
cluster_id
balance
G1
0.5

cluster_id	balance
G1	0.5