MetricsConfig — Metrics System Configuration

MetricsConfig is the configuration of the MetricsSystem (i.e. metrics sources and sinks).

MetricsConfig uses as the default metrics configuration file that can however be changed using spark.metrics.conf property. The file is first loaded from the path directly before using Spark’s CLASSPATH.

MetricsConfig lets you also configure the metrics configuration using spark.metrics.conf.-prefixed Spark properties.

MetricsConfig makes sure that the default metrics properties are always defined.

Table 1. MetricsConfig’s Default Metrics Properties
Name Description










The order of precedence of metrics configuration settings is as follows:

  1. Default metrics properties

  2. spark.metrics.conf or configuration file

  3. spark.metrics.conf.-prefixed Spark properties

MetricsConfig is created when MetricsSystem is created.

Table 2. MetricsConfig’s Internal Registries and Counters
Name Description


java.util.Properties with metrics properties

Used to initialize per-subsystem’s perInstanceSubProperties.


Lookup table of metrics properties per subsystem

Creating MetricsConfig Instance

MetricsConfig takes the following when created:

MetricsConfig initializes the internal registries and counters.

Initializing MetricsConfig — initialize Method

initialize(): Unit

initialize takes all Spark properties that start with spark.metrics.conf. prefix from SparkConf and adds them to properties (without the prefix).

In the end, initialize splits configuration per Spark subsystem with the default configuration (denoted as *) assigned to the configured subsystems afterwards.

initialize accepts * (star) for the default configuration or any combination of lower- and upper-case letters for Spark subsystem names.
initialize is used exclusively when MetricsSystem is created.

setDefaultProperties Internal Method

setDefaultProperties(prop: Properties): Unit

setDefaultProperties sets the default properties (in the input prop).

setDefaultProperties is used exclusively when MetricsConfig is initialized.

Loading Custom Metrics Configuration File or — loadPropertiesFromFile Method

loadPropertiesFromFile(path: Option[String]): Unit

loadPropertiesFromFile tries to open the input path file (if defined) or the default metrics configuration file (on CLASSPATH).

If either file is available, loadPropertiesFromFile loads the properties (to properties registry).

In case of exceptions, you should see the following ERROR message in the logs followed by the exception.

ERROR Error loading configuration file [file]
loadPropertiesFromFile is used exclusively when MetricsConfig is initialized.

Grouping Properties Per Subsystem — subProperties Method

subProperties(prop: Properties, regex: Regex): mutable.HashMap[String, Properties]

subProperties takes prop properties and destructures keys given regex. subProperties takes the matching prefix (of a key per regex) and uses it as a new key with the value(s) being the matching suffix(es). => (driver, (
subProperties is used when MetricsConfig is initialized (to apply the default metrics configuration) and when MetricsSystem registers metrics sources and sinks.


Table 3. Spark Properties
Spark Property Default Value Description


The metrics configuration file.

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