Liftwizard: Instrumentation Metrics

Instrumentation Metrics

Thu Mar 13 2025

LiftwizardGraphQLMetricsInstrumentation is an implementation of Instrumentation from GraphQL Java that registers performance metrics about data fetching with Dropwizard's MetricsRegistry.

To turn it on, either run the entire LiftwizardGraphQLBundle or just add LiftwizardGraphQLMetricsInstrumentation to the list of instrumentations on your GraphQLFactory.

GraphQLFactory factory = ...;

Clock clock = Clock.systemUTC();

var metricsInstrumentation = new LiftwizardGraphQLMetricsInstrumentation(this.metricRegistry, clock);
var loggingInstrumentation = new LiftwizardGraphQLLoggingInstrumentation();

List<Instrumentation> instrumentations = List.of(metricsInstrumentation, loggingInstrumentation);
factory.setInstrumentations(instrumentations);

Annotations

Next, annotate the DataFetchers that you want to monitor with @Timed, @Metered, and/or @ExceptionMetered. You can annotate either the get() method, or the entire fetcher class.

Timers

@Timed adds three timers:

{DataFetcher's fully-qualified class name}.get.sync
liftwizard.graphql.field.{GraphQL Class}.{GraphQL field}.sync
liftwizard.graphql.path.{path}.sync

All three timers track the number of times each DataFetcher is called, and the amount of time spent in the get() method.

Although the timers measure the same thing, they may not have identical values. This would happen if the same DataFetcher is wired to multiple fields, or is reached by multiple paths through the graph.

If your DataFetcher returns CompleteableFuture, you'll get three additional timers, with names ending in "async" instead of "sync". Rather than track the amount of time spent in get(), these timers will track the amount of time until the CompleteableFutures complete.

Meters

Timers are meters, so if you want to know the number of times a fetcher is called, annotate them with @Timer.

If you annotate your DataFetcher with @Metered, the Intrumentation will add meters that track the number of items returned by the DataFetcher. If the DataFetcher returns a Collection or CompleteableFuture<Collection>, the meter will increment by the size of the Collection.

ExceptionMeters

@ExceptionMetered adds meters that track the number of times the DataFetcher throws uncaught exceptions, plus the number of CompleteableFutures they return that complete exceptionally. The meters have the same names as the timers, but with the suffix "exceptions":

{DataFetcher's fully-qualified class name}.get.exceptions
liftwizard.graphql.field.{GraphQL Class}.{GraphQL field}.exceptions
liftwizard.graphql.path.{path}.exceptions

LiftwizardGraphQLMetricsInstrumentation lives in the liftwizard-graphql-instrumentation-metrics module.

<dependency>
    <groupId>io.liftwizard</groupId>
    <artifactId>liftwizard-graphql-instrumentation-metrics</artifactId>
</dependency>