best practices : should we reuse the instruments ?

[antonmithun-work]

I am using the below code to record the time taken for a function. but I am creating histogram instrument for every request.

let meter = global::meter("local_time_meter"); let counter = meter .u64_counter("example_counter") .with_description("Counts occurrences of events") .build(); counter.add(1, &[KeyValue::new("test", "test")]); let processing_time = meter.f64_histogram("processing_time").build(); processing_time.record(start.elapsed().as_secs_f64(), &[]);
I think its better if I encapsulate this histogram in a separete module and internally reuse the histogram created in the consturctor to record the data

so I try to do something like this

use opentelemetry_sdk::metrics::data::Histogram;

let kd_tree_build_time: Histogram<f64> =
            meter.f64_histogram("fn_time").build();

But I am getting type mismatch error

Type mismatch [E0308] expected Histogram<f64>, but found opentelemetry::metrics::instruments::histogram::Histogram<f64>

these are my dependencies
opentelemetry = { version = "0.28.0", features = ["trace", "metrics"] } opentelemetry-otlp = { version= "0.28.0", features = ["tonic", "grpc-tonic"] } opentelemetry_sdk = { version = "0.28.0", features = ["rt-tokio", "rt-tokio-current-thread"] } opentelemetry-semantic-conventions = { version= "0.28.0" } opentelemetry-stdout = "0.28.0" tracing = "0.1.41" tracing-opentelemetry = "0.29.0" tracing-subscriber = { version = "0.3.19"}

Qs :

1. Is it better to reuse the instruments
2. how can I resolve this issue so that I can store the instrument to use it later

thanks in advance

[cijothomas]

Create once and re-use. If not easy to pass around the created instance, clone and share. (Cloning is cheap and will point to the same underlying Metric).

https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry/src/metrics/instruments/histogram.rs#L7-L11

[cijothomas]

use opentelemetry_sdk::metrics::data::Histogram;
This is not the Histogram instrument, this is an SDK construct, useful for custom exporter authors.