Method resetConcurrency

pkg/querier/worker/worker.go:242–279

Must be called with lock.

()

// Must be called with lock.
func (w *querierWorker) resetConcurrency() {
	totalConcurrency := 0
	index := 0

	for _, m := range w.managers {
		concurrency := 0

		if w.cfg.MatchMaxConcurrency {
			concurrency = w.cfg.MaxConcurrentRequests / len(w.managers)

			// If max concurrency does not evenly divide into our frontends a subset will be chosen
			// to receive an extra connection.  Frontend addresses were shuffled above so this will be a
			// random selection of frontends.
			if index < w.cfg.MaxConcurrentRequests%len(w.managers) {
				level.Warn(w.log).Log("msg", "max concurrency is not evenly divisible across targets, adding an extra connection", "addr", m.address)
				concurrency++
			}
		} else {
			concurrency = w.cfg.Parallelism
		}

		// If concurrency is 0 then MaxConcurrentRequests is less than the total number of
		// frontends/schedulers. In order to prevent accidentally starving a frontend or scheduler we are just going to
		// always connect once to every target.  This is dangerous b/c we may start exceeding PromQL
		// max concurrency.
		if concurrency == 0 {
			concurrency = 1
		}

		totalConcurrency += concurrency
		m.concurrency(concurrency)
		index++
	}

	if totalConcurrency > w.cfg.MaxConcurrentRequests {
		level.Warn(w.log).Log("msg", "total worker concurrency is greater than promql max concurrency. Queries may be queued in the querier which reduces QOS")
	}
}

func (w *querierWorker) connect(address string) (*grpc.ClientConn, error) {
	// Because we only use single long-running method, it doesn't make sense to inject user ID, send over tracing or add metrics.