P99 Latency Monitoring

Context

The Elasticsearch community only discusses how to monitor the average latency of search requests, which cannot reflect the actual search performance of a cluster. To enhance monitoring, CSS allows you to monitor the P99 latency of search requests in clusters.

Prerequisites

Currently, only clusters of version 7.6.2 support P99 latency monitoring.

Obtaining Monitoring Information

1. Log in to the CSS management console.
2. Choose Clusters in the navigation pane. On the Clusters page, locate the target cluster and click Access Kibana in the Operation column.
3. In the navigation tree on the left, choose Dev Tools and run the following command to check the P99 latency of the current cluster:

   GET /search/stats/percentile 

   Example response:

   {
     "overall" : {
       "1.0" : 2.0,
       "5.0" : 2.0,
       "25.0" : 6.5,
       "50.0" : 19.5,
       "75.0" : 111.0,
       "95.0" : 169.0,
       "99.0" : 169.0,
       "max" : 169.0,
       "min" : 2.0
     },
     "last_one_day" : {
       "1.0" : 2.0,
       "5.0" : 2.0,
       "25.0" : 6.5,
       "50.0" : 19.5,
       "75.0" : 111.0,
       "95.0" : 169.0,
       "99.0" : 169.0,
       "max" : 169.0,
       "min" : 2.0
     },
     "latest" : {
       "1.0" : 26.0,
       "5.0" : 26.0,
       "25.0" : 26.0,
       "50.0" : 26.0,
       "75.0" : 26.0,
       "95.0" : 26.0,
       "99.0" : 26.0,
       "max" : 26.0,
       "min" : 26.0
     }
   }

   

   • In the response, overall indicates all the statistics that have been collected since the cluster startup, last_one_day indicates the statistics collected in the last day, and latest indicates the statistics that have been collected since the last reset.
   • The calculated P99 latency is an estimation. It is more precise than the P50 latency.
   • The P99 latency of a cluster is cleared and recalculated if the cluster is restarted.

Other Operations

• Define percentage.
  You can run the following command to specify the percentage:

  GET /search/stats/percentile
  {
    "percents": [1, 50, 90]
  }

• Reset the latest statistics.
  You can run the following command to reset the latest statistics:

  POST /search/stats/reset

  Example response:

  {
    "nodes" : {
      "css-c9c8-ess-esn-1-1" : "ok"
    }
  }