Explicit metrics reading/exporting instead keeps sending Metrics on fix intervals.

[swapnil-kotwal-sp]

I'm having below implementation of PeriodicMetricReader which actually keeps sending Metrics on fix intervals of 60 seconds

 public static OpenTelemetry initOpenTelemetry() {
    // Create an instance of PeriodicMetricReader and configure it
    // to export via the logging exporter
    MetricReader periodicReader =
        PeriodicMetricReader.builder(LoggingMetricExporter.create())
            .setInterval(Duration.ofSeconds(METRICS_EXPORT_INTERVAL_SEC))
            .build();

    // This will be used to create instruments
    SdkMeterProvider meterProvider =
        SdkMeterProvider.builder().registerMetricReader(periodicReader).build();

    // Tracer provider configured to export spans with SimpleSpanProcessor using
    // the logging exporter.
    SdkTracerProvider tracerProvider =
        SdkTracerProvider.builder()
            .addSpanProcessor(SimpleSpanProcessor.create(LoggingSpanExporter.create()))
            .build();
    return OpenTelemetrySdk.builder()
        .setMeterProvider(meterProvider)
        .setTracerProvider(tracerProvider)
        .buildAndRegisterGlobal();
  }

Can I change it something that it should only send metrics when there is new operation get called or an event happened instead of constantly sending data to Otel-collector at fix intervals?

I found some discussions here and here as well but didn't get any java examples. Can someone please help me with?

[swapnil-kotwal-sp]

I've Implemented something below to send metrics immediately(when needed) instead of at certain interval like 60 seconds etc. Does it have any drawbacks or anything special I should consider here?

public class CustomMetricReader implements MetricReader {

	private static final Logger logger = Logger.getLogger(CustomMetricReader.class.getName());

	private final AtomicReference<CollectionRegistration> collectionRef = new AtomicReference<>(CollectionRegistration.noop());
	private final OtlpGrpcMetricExporter otlpGrpcMetricsExporter;

	public CustomMetricReader(OtlpGrpcMetricExporter otlpGrpcMetricsExporter) {
		this.otlpGrpcMetricsExporter = otlpGrpcMetricsExporter;
	}

	@Override
	public void register(CollectionRegistration collectionRegistration) {
		collectionRef.set(collectionRegistration);
	}

	private void collectMetrics() {
		logger.log(Level.INFO, "Collecting metrics");
		Collection<MetricData> metrics = collectionRef.get().collectAllMetrics();
		otlpGrpcMetricsExporter.export(metrics);
	}

	@Override
	public CompletableResultCode forceFlush() {
		// Export any records which have been queued up but not yet exported.
		return otlpGrpcMetricsExporter.flush();
	}

	@Override
	public CompletableResultCode shutdown() {
		logger.log(Level.INFO, "Shutting Down CCGMetricReader...");
		return otlpGrpcMetricsExporter.shutdown();
	}

	@Override
	public AggregationTemporality getAggregationTemporality(InstrumentType instrumentType) {
		return AggregationTemporalitySelector.deltaPreferred().getAggregationTemporality(instrumentType);
	}
}

[swapnil-kotwal-sp]

@srikanthccv @howardyoo any thoughts, it would be great help for me proceed with to choose either

setMeterProvider(SdkMeterProvider.builder().setResource(resource)
.registerMetricReader(PeriodicMetricReader.builder(otlpGrpcMetricsExporter)
 .setInterval(Duration.ofSeconds(METRICS_EXPORT_INTERVAL_SEC)).build()).build())

OR CustomMetricReader implementation as above?

[howardyoo]

Hey @swapnil-kotwal-sp , I'm not opinionated on this in any way, looks like your custom metric reader can work, and if it works, it should be good...? Not sure what your are having thoughts on...?