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Named run configurations

nvim-jfr can optionally load project-only run configurations from:

<root>/.jfr/run-configs.lua

Run configs let you name common recording presets (settings, duration, overrides) and select them when starting a recording.

File format

Create <root>/.jfr/run-configs.lua:

return {
  -- Optional: which config should be treated as the default.
  default = "profile-60s",

  -- Required: map of name -> config.
  configs = {
    ["profile-60s"] = {
      settings = "profile", -- "default" | "profile" | path to .jfc
      duration = "60s",
      start_overrides = {
        maxsize = "250M",
        maxage = "10m",
      },
    },

    ["alloc"] = {
      settings = ".jfr/templates/alloc.jfc",
      duration = "5m",
    },
  },
}

Starting with a run config

Use:

:JFRStart --run=profile-60s

If you don’t pass --run=... and the file exists, :JFRStart will:

  1. prompt for JVM
  2. prompt for run config

If the file sets default = "...", that config is presented first in the picker (best-effort) so it behaves like a default choice across picker backends.

Skipping run config selection

:JFRStart --run=none

This forces “manual mode” (no run config applied).

What a run config can contain

Each config supports:

  • settings: "default" | "profile" | <path-to-.jfc>
  • duration: a string like "60s", "5m"
  • start_overrides: a table of extra JFR.start options (capability-gated)

Example with overrides:

return {
  configs = {
    ["profile-capped"] = {
      settings = "profile",
      duration = "60s",
      start_overrides = {
        maxage = "10m",
        maxsize = "250M",
      },
    },
  },
}

Path constraint (required)

When settings in a run config is a .jfc file, it must resolve under:

<root>/.jfr/templates/

This keeps run configs portable and project-local.

You can still use any .jfc path manually via:

:JFRStart --settings=/any/path/to/file.jfc

Merge precedence

When a run config is selected:

  • CLI args win (e.g. --duration=..., --settings=...)
  • then the run config values
  • then your require("nvim-jfr").setup({ ... }) defaults

If you pass both CLI overrides and run config overrides, they are merged in the same order:

  1. setup().start_overrides
  2. run-configs.lua start_overrides
  3. CLI overrides (--opt=... or --key=value)