merge region reach limit while there is no any operator

[lhy1024]

Bug Report

What did you do?

merge empty region

What did you expect to see?

What did you see instead?

there has been no operator check, but it still reaches limit

What version of PD are you using (pd-server -V)?

[lhy1024]

I am not sure whether it is related to evict-slow-store-scheduler

I try to adjust merge-schedule-limit and remove evict-slow-store-scheduler, it works again.

[LykxSassinator]

any metrics on TIKV side can be checked and reviewed ?

[lhy1024]

It occurs again, there is no any merge operator, but it shows schedulers reach limit until merge-scheduler-limit is set to 512

I guess there maybe a statistic problem with the operator count. There are some retain operators in PD.

[lhy1024]

I try add log, and found operator count is error

if c.mergeChecker != nil {
		allowed := opController.OperatorCount(operator.OpMerge) < c.conf.GetMergeScheduleLimit()
		if !allowed {
			log.Debug("merge check allowed", zap.Int("operators", len(opController.GetOperators())),
				zap.Uint64("count", opController.OperatorCount(operator.OpMerge)), zap.Uint64("limit", c.conf.GetMergeScheduleLimit()))
			operator.IncOperatorLimitCounter(c.mergeChecker.GetType(), operator.OpMerge)
		} else if ops := c.mergeChecker.Check(region); ops != nil {
			// It makes sure that two operators can be added successfully altogether.
			return ops
		}
	}