class CounterA counter is a cumulative metric that represents a single monotonically increasing counter whose value can only increase or be reset to zero. For example, you can use a counter to represent the number of requests served, tasks completed, or errors.
class MeterA meter is similar to a gauge, it is a metric that represents a single numerical value that can arbitrarily go up and down. Meters are typically used for measured values like temperatures or current memory usage, but also “counts” that can go up and down, like the number of active threads.
class RecorderA recorder collects observations within a time window (usually things like response sizes) and can provide aggregated information about the data sample, for example, count, sum, min, max and various quantiles.
class GaugeA gauge is a metric that represents a single numerical value that can arbitrarily go up and down. Gauges are typically used for measured values like temperatures or current memory usage, but also “counts” that can go up and down, like the number of active threads. Gauges are modeled as Recorder with a sample size of 1 and that does not perform any aggregation.
class TimerA timer collects observations within a time window (usually things like request durations) and provides aggregated information about the data sample, for example, min, max and various quantiles. It is similar to a Recorder but specialized for values that represent durations.