* Use a simple counter for sampler duration instead of a histogram.
* Use a counter to collect GC time.
* Remove unused objects metric.
* Cleanup metric names to match Prometheus conventions.
* Prefix generic GC stats with `gc_stat`.
* Include worker label on memory and file descriptor metrics.

Marcel Amirault authored 6 years ago and Achilleas Pipinellis committed 6 years ago

(cherry picked from commit b5ea33397eb8d2c874662026b0e36aed7c41dbbc)

This will only be displayed if `X-GitLab-Show-Login-Captcha` is set as an HTTP
header.

A background column type change needs a cleanup step, like any background
migration. We should call that out explicitly in the documentation.

Save people an extra Google search if this is the
first doc they're reading.