Metrics

Like the FactCast server, also Factus makes use of micrometer.io metrics.

Metric namespaces and their organization

At the time of writing, there are three namespaces exposed:

• factus.timings
• factus.counts
• factus.gauges

Depending on your micrometer binding, you may see a slightly different spelling in your data (like ' factus_timings`, if your datasource has a special meaning for the ‘.’-character)

The metrics are automatically tagged with

• the emitting class (class tag)
• the name of the metric (name tag)

Existing Metrics

At the time of writing (Factcast version 0.3.13) the following metrics are supported:

Counted

• transaction_attempts - how often was a transaction retried. See Optimistic Locking for more background
• transaction_abort - how often was an attempted transaction aborted

Gauged

• fetch_size - size in bytes of a fetched Snapshot projection or Aggregate projection

Timed

• managed_projection_update_duration - duration in milliseconds a Managed Projection took to update
• fetch_duration - duration in milliseconds it took to fetch a Snapshot projection
• find_duration - duration in milliseconds it took to find a specific Aggregate
• event_processing_latency - for those facts that arrive after catchup: time difference in milliseconds between a fact was published and recieved by a client. (In case of batch processing, this is only reported for the first/oldest fact of a batch)