---
name: "Net::Prometheus::Histogram"
section: "3pm"
platform: "linux"
package: "libnet-prometheus-perl"
version: "0.14-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Net::Prometheus::Histogram"
---

# Net::Prometheus::Histogram(3pm)

count the distribution of numeric observations

## NAME

"Net::Prometheus::Histogram" - count the distribution of numeric observations

## SYNOPSIS

```
   use Net::Prometheus;
   use Time::HiRes qw( time );
   my $client = Net::Prometheus->new;
   my $histogram = $client->new_histogram(
      name => "request_seconds",
      help => "Summary request processing time",
   );
   sub handle_request
   {
      my $start = time();
      ...
      $summary->observe( time() - $start );
   }
```

## DESCRIPTION

This class provides a histogram metric - a count of the distribution of individual numerical observations into distinct buckets. These are usually reports of times. It is a subclass of Net::Prometheus::Metric.

## CONSTRUCTOR

Instances of this class are not usually constructed directly, but instead via the Net::Prometheus object that will serve it:

```
   $histogram = $prometheus->new_histogram( %args );
```

This takes the same constructor arguments as documented in Net::Prometheus::Metric, and additionally the following:

- buckets =\> ARRAY

  A reference to an ARRAY containing numerical upper bounds for the buckets.

- bucket\_min =\> NUM

  - bucket\_max =\> NUM

  - buckets\_per\_decade =\> ARRAY\[ NUM \]

  *Since version 0.10.*

  A more flexible alternative to specifying literal bucket sizes. The values given in `"buckets_per_decade"` are repeated, multiplied by various powers of 10 to generate values between `"bucket_min"` (or a default of 0.001 if not supplied) and `"bucket_max"` (or a default of 1000 if not supplied).

### bucket\_bounds

```
   @bounds = $histogram->bucket_bounds;
```

Returns the bounding values for each of the buckets, excluding the final `"+Inf"` bucket.

### observe

```
   $histogram->observe( @label_values, $value );
   $histogram->observe( \%labels, $value );
   $child->observe( $value );
```

Increment the histogram sum by the given value, and each bucket count by 1 where the value is less than or equal to the bucket upper bound.

## AUTHOR

Paul Evans \<leonerd@leonerd.org.uk\>