| Name | Description | Type | Package | Framework |
| DefaultMetricsSystem | enum DefaultMetricsSystemThe default metrics system singleton | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop |
| Interns | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MetricsRegistry | An optional metrics registry class for creating and maintaining a collection of MetricsMutables, making writing metrics source easier. | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop |
| MutableCounter | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableCounterInt | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableCounterLong | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableGauge | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableGaugeInt | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableGaugeLong | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableMetric | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableQuantiles | Watches a stream of long values, maintaining online estimates of specific quantiles with provably low error bounds. | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop |
| MutableRate | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableRates | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop | |
| MutableStat | A mutable metric with stats. | Class | org.apache.hadoop.metrics2.lib | Apache Hadoop |