Events Ping Acceleration Factor

By default, Glean batches events together to submit on a single "events" ping. The number of events Glean will collect before submitting an "events" ping is determined at Glean initialization via the maxEvents configuration option and can be changed remotely via the event_threshold Server Knob.

This Server Knob overrides the eventsPingAccelerationFactor configuration option from Glean initialization. It takes effect immediately, but if the number of "events" pings already submitted this session exceeds the factor, it might have no practical effect.

Example Configuration:

{
  "gleanMetricConfiguration": {
    "events_ping_acceleration_factor": 5
  }
}

Server Knobs Configuration in Pings

When Server Knobs configuration is applied through applyServerKnobsConfig, the entire configuration is automatically recorded as an ObjectMetric and included in the ping_info section of all pings except for those with metadata.include_info_sections: false.

This makes it easier to identify which metrics are being controlled by Server Knobs and to calculate effective sampling rates in analysis.

The configuration is stored using a standard ObjectMetric (at glean.internal.metrics.server_knobs_config), which provides schema definition support for downstream tooling and requires minimal changes to ingestion pipeline schemas.

How It Appears in Pings

The complete Server Knobs configuration is included in ping_info.server_knobs_config:

{
  "ping_info": {
    "seq": 123,
    "start_time": "2024-01-01T00:00:00Z",
    "end_time": "2024-01-01T01:00:00Z",
    "server_knobs_config": {
      "metrics_enabled": {
        "urlbar.engagement": true,
        "urlbar.impression": true
      }
    }
  },
  "metrics": {
    "counter": {
      "urlbar.engagement": 5,
      "urlbar.impression": 2
    }
  }
}