Support for scheduled metrics reporting

This came up during Spring Boot 1.5 to 2.0 and dropwizard + metrics-coursera to micrometer migration. The former couple uses ScheduledReporter so metrics, even though they are sent immediately by java-dogstatsd-client, are not reported immediately but rather by a schedule like every 5 or 10 seconds. This creates a room to breathe for the agent. Micrometer floods the agent with immediate reporting as my service generates about 10-15K metrics per second as a part of request tracking. Right now there’s a 20% toll when metrics are collected in such scenario consumed by datadog agent.

There seem to be a few options:

1. Adopt scheduled reporting as a configurable option
2. datadog-agent v6 supports batch reporting

[jkschneider]

The statsd registry now buffers statsd lines together using @breun’s implementation based on Nagle’s algorithm. This happens by default without any configuration. This is really a better approach than a regular scheduled push, as infrequent timings are emitted immediately, and frequent timings get batched up.

The same approach is not relevant to other registry types. Only statsd requires emission on a per timing basis. Most other registries do scheduled reporting on a predefined interval.

[breun]

I’ve talked to Reactor committers and am working on an implementation of Nagle’s algorithm, at least for the StatsD registry, which is actually not trivial using the currently available Reactor operators. I don’t think there is a generic way to implement this for all meter registries by the way.