Struct PeriodicReader

pub struct PeriodicReader { /* private fields */ }

A MetricReader that periodically collects and exports metrics at a configurable interval.

By default, PeriodicReader collects and exports metrics every 60 seconds. The time taken for export is not included in the interval. Use PeriodicReaderBuilder to customize the interval.

PeriodicReader spawns a background thread to handle metric collection and export. This thread remains active until shutdown() is called.

Collection Process

“Collection” refers to gathering aggregated metrics from the SDK’s internal storage. During this phase, callbacks from observable instruments are also triggered.

PeriodicReader does not enforce a timeout for collection. If an observable callback takes too long, it may delay the next collection cycle. If a callback never returns, it will stall all metric collection (and exports) indefinitely.

Exporter Compatibility

When used with the OTLP Exporter, the following transport options are supported:

• grpc-tonic: Requires MeterProvider to be initialized within a tokio runtime.
• reqwest-blocking-client: Works with both a standard (main) function and tokio::main.

PeriodicReader does not enforce a timeout for exports either. Instead, the configured exporter is responsible for enforcing timeouts. If an export operation never returns, PeriodicReader will stop exporting new metrics, stalling metric collection.

Manual Export & Shutdown

Users can manually trigger an export via force_flush(). Calling shutdown() exports any remaining metrics and should be done before application exit to ensure all data is sent.

Warning: If using tokio’s current-thread runtime, calling shutdown() from the main thread may cause a deadlock. To prevent this, call shutdown() from a separate thread or use tokio’s spawn_blocking.

Example

use opentelemetry_sdk::metrics::PeriodicReader;

let exporter = get_exporter(); // set up a push exporter

let reader = PeriodicReader::builder(exporter).build();

Implementations

impl PeriodicReader

pub fn builder<E>(exporter: E) -> PeriodicReaderBuilder<E>

where E: PushMetricExporter,

Configuration options for a periodic reader with own thread

Trait Implementations

impl Clone for PeriodicReader

fn clone(&self) -> PeriodicReader

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PeriodicReader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl MetricReader for PeriodicReader

fn temporality(&self, kind: InstrumentKind) -> Temporality

To construct a MetricReader when setting up an SDK, The output temporality (optional), a function of instrument kind. This function SHOULD be obtained from the exporter.

If not configured, the Cumulative temporality SHOULD be used.

fn register_pipeline(&self, pipeline: Weak<Pipeline>)

Registers a MetricReader with a [Pipeline].

fn collect(&self, rm: &mut ResourceMetrics) -> MetricResult<()>

Gathers and returns all metric data related to the MetricReader from the SDK and stores it in the provided ResourceMetrics reference.

fn force_flush(&self) -> OTelSdkResult

Flushes all metric measurements held in an export pipeline.

fn shutdown(&self) -> OTelSdkResult

Flushes all metric measurements held in an export pipeline and releases any held computational resources.