// mrf backlog stats
	mrfStats ReplicationMRFStats
	// for bucket replication, continue to use existing cache
	Cache             map[string]*BucketReplicationStats
	mostRecentStats   BucketStatsMap
	registry          metrics.Registry
	sync.RWMutex                 // mutex for Cache
	mostRecentStatsMu sync.Mutex // mutex for mostRecentStats

	wlock sync.RWMutex // mutex for active workers

func metricsNodeHandler() http.Handler {
	registry := prometheus.NewRegistry()

	logger.CriticalIf(GlobalContext, registry.Register(nodeCollector))
	if err := registry.Register(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{
		Namespace:    minioNamespace,
		ReportErrors: true,
	})); err != nil {
		logger.CriticalIf(GlobalContext, err)
	}
	if err := registry.Register(prometheus.NewGoCollector()); err != nil {

	bucketMGMap map[collectorPath]*MetricsGroup

	// Gatherers for non-bucket MetricsGroup's
	mgGatherers map[collectorPath]prometheus.Gatherer

	collectorPaths []collectorPath
}

func newMetricGroups(r *prometheus.Registry) *metricsV3Collection {
	// Create all metric groups.
	apiRequestsMG := NewMetricsGroup(apiRequestsCollectorPath,
		[]MetricDescriptor{
			apiRejectedAuthTotalMD,
			apiRejectedHeaderTotalMD,