| expvar | Package expvar provides a standardized interface to public variables, such as operation counters in servers. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/codahale/hdrhistogram | |
| github.com/go-kit/kit/metrics | Package metrics provides a framework for application instrumentation. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |