improve --rules.max-concurrent-evals description.

[machine424]

Proposal

Suggest to adjust –query.max-concurrency when changing --rules.max-concurrent-evals as the rules manager uses the same query engine than the API:

prometheus/cmd/prometheus/main.go

Lines 743 to 772 in 4a6f870

	opts := promql.EngineOpts{
	Logger: log.With(logger, "component", "query engine"),
	Reg: prometheus.DefaultRegisterer,
	MaxSamples: cfg.queryMaxSamples,
	Timeout: time.Duration(cfg.queryTimeout),
	ActiveQueryTracker: promql.NewActiveQueryTracker(localStoragePath, cfg.queryConcurrency, log.With(logger, "component", "activeQueryTracker")),
	LookbackDelta: time.Duration(cfg.lookbackDelta),
	NoStepSubqueryIntervalFn: noStepSubqueryInterval.Get,
	// EnableAtModifier and EnableNegativeOffset have to be
	// always on for regular PromQL as of Prometheus v2.33.
	EnableAtModifier: true,
	EnableNegativeOffset: true,
	EnablePerStepStats: cfg.enablePerStepStats,
	}
	queryEngine = promql.NewEngine(opts)
	ruleManager = rules.NewManager(&rules.ManagerOptions{
	Appendable: fanoutStorage,
	Queryable: localStorage,
	QueryFunc: rules.EngineQueryFunc(queryEngine, fanoutStorage),
	NotifyFunc: rules.SendAlerts(notifierManager, cfg.web.ExternalURL.String()),
	Context: ctxRule,
	ExternalURL: cfg.web.ExternalURL,
	Registerer: prometheus.DefaultRegisterer,
	Logger: log.With(logger, "component", "rule manager"),
	OutageTolerance: time.Duration(cfg.outageTolerance),
	ForGracePeriod: time.Duration(cfg.forGracePeriod),
	ResendDelay: time.Duration(cfg.resendDelay),
	MaxConcurrentEvals: cfg.maxConcurrentEvals,

Add that to --rules.max-concurrent-evals's description:

prometheus/cmd/prometheus/main.go

Line 420 in 6332248

serverOnlyFlag(a, "rules.max-concurrent-evals", "Global concurrency limit for independent rules that can run concurrently.").

Was discussed here: https://cloud-native.slack.com/archives/C167KFM6C/p1712665137550239

[kushalShukla-web]

is this pr solves the issue @machine424 ??