A Counter is used to measure the rate at which some event is occurring. Considering a simple queue, Counters could be used to measure things like the rate at which items are being inserted and removed.
Counters are reported to the backend as a rate-per-second. This makes it much easier to reason about the measurement and allows for aggregating the counter across instances.
In Atlas, the
:per-step operator can be used to convert them back into a count-per-step on a
For high performance code, such as incrementing in a tight loop that lasts less than a reporting interval, increment a local variable and add the final value to the counter after the loop has completed.