Fluo Metrics

A Fluo application can be configured (in fluo.properties) to report metrics. When metrics are configured, Fluo will report some ‘default’ metrics about an application that help users monitor its performance. Users can also write code to report ‘application-specific’ metrics from their applications. Both ‘application-specific’ and ‘default’ metrics share the same reporter configured by fluo.properties and are described in detail below.

Configuring reporters

Fluo metrics are not published by default. To publish metrics, configure a reporter in the ‘metrics’ section of fluo.properties. There are several different reporter types (i.e Console, CSV, Graphite, JMX, SLF4J) that are implemented using Dropwizard. The choice of which reporter to use depends on the visualization tool used. If you are not currently using a visualization tool, there is documentation for reporting Fluo metrics to Grafana/InfluxDB.

Metrics names

When Fluo metrics are reported, they are published using a naming scheme that encodes additional information. This additional information is represented using all caps variables (i.e METRIC) below.

Default metrics start with fluo.class or fluo.system and have following naming schemes:


Application metrics start with fluo.app and have following scheme:


The variables below describe the additional information that is encoded in metrics names.

  1. APPLICATION - Fluo application name
  2. REPORTER_ID - Unique ID of the Fluo oracle, worker, or client that is reporting the metric. When running in YARN, this ID is of the format worker-INSTANCE_ID or oracle-INSTANCE_ID where INSTANCE_ID corresponds to instance number. When not running in YARN, this ID consists of a hostname and a base36 long that is unique across all fluo processes.
  3. METRIC - Name of the metric. For ‘default’ metrics, this is set by Fluo. For ‘application’ metrics, this is set by user. Name should be unique and avoid using period ‘.’ in name.
  4. CLASS - Name of Fluo observer or loader class that produced metric. This allows things like transaction collisions to be tracked per class.

Application-specific metrics

Application metrics are implemented by retrieving a MetricsReporter from an Observer, Loader, or FluoClient. These metrics are named using the format fluo.app.REPORTER_ID.METRIC.

Default metrics

Default metrics report for a particular Observer/Loader class or system-wide.

Below are metrics that are reported from each Observer/Loader class that is configured in a Fluo application. These metrics are reported after each transaction and named using the format fluo.class.APPLICATION.REPORTER_ID.METRIC.CLASS.

  • tx_lock_wait_time - Timer
    • Time transaction spent waiting on locks held by other transactions.
    • Only updated for transactions that have non-zero lock time.
  • tx_execution_time - Timer
    • Time transaction took to execute.
    • Updated for failed and successful transactions.
    • This does not include commit time, only the time from start until commit is called.
  • tx_with_collision - Meter
    • Rate of transactions with collisions.
  • tx_collisions - Meter
    • Rate of collisions.
  • tx_entries_set - Meter
    • Rate of row/columns set by transaction
  • tx_entries_read - Meter
    • Rate of row/columns read by transaction that existed.
    • There is currently no count of all reads (including non-existent data)
  • tx_locks_timedout - Meter
    • Rate of timedout locks rolled back by transaction.
    • These are locks that are held for very long periods by another transaction that appears to be alive based on zookeeper.
  • tx_locks_dead - Meter
    • Rate of dead locks rolled by a transaction.
    • These are locks held by a process that appears to be dead according to zookeeper.
  • tx_status_<STATUS> - Meter
    • Rate of different ways (i.e <STATUS>) a transaction can terminate

Below are system-wide metrics that are reported for the entire Fluo application. These metrics are named using the format fluo.system.APPLICATION.REPORTER_ID.METRIC.

  • oracle_response_time - Timer
    • Time each RPC call to oracle for stamps took
  • oracle_client_stamps - Histogram
    • Number of stamps requested for each request for stamps to the server
  • oracle_server_stamps - Histogram
    • Number of stamps requested for each request for stamps from a client
  • worker_notifications_queued - Gauge
    • The current number of notifications queued for processing.
  • transactor_committing - Gauge
    • The current number of transactions that are working their way through the commit steps.

Histograms and Timers have a counter. In the case of a histogram, the counter is the number of times the metric was updated and not a sum of the updates. For example if a request for 5 timestamps was made to the oracle followed by a request for 3 timestamps, then the count for oracle_server_stamps would be 2 and the mean would be (5+3)/2.