From e228f479a517079c1754e2173a5b871f73e867d5 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Thu, 20 May 2021 02:47:22 +0300
Subject: [PATCH] lib/storage: remove possible data race when logging dropped
 labels

---
 lib/storage/metric_name.go | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/lib/storage/metric_name.go b/lib/storage/metric_name.go
index 1b1047467..5816bee9c 100644
--- a/lib/storage/metric_name.go
+++ b/lib/storage/metric_name.go
@@ -8,10 +8,10 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
 )
@@ -567,21 +567,16 @@ var (
 
 func trackDroppedLabels(labels, droppedLabels []prompb.Label) {
 	atomic.AddUint64(&MetricsWithDroppedLabels, 1)
-	ct := fasttime.UnixTimestamp()
-	if ct < atomic.LoadUint64(&droppedLabelsLogNextTimestamp) {
-		return
-	}
-	droppedLabelsLogOnce.Do(func() {
-		atomic.StoreUint64(&droppedLabelsLogNextTimestamp, ct+5)
+	select {
+	case <-droppedLabelsLogTicker.C:
 		logger.Warnf("dropping %d labels for %s; dropped labels: %s; either reduce the number of labels for this metric "+
 			"or increase -maxLabelsPerTimeseries=%d command-line flag value",
 			len(droppedLabels), labelsToString(labels), labelsToString(droppedLabels), maxLabelsPerTimeseries)
-		droppedLabelsLogOnce = &sync.Once{}
-	})
+	default:
+	}
 }
 
-var droppedLabelsLogOnce = &sync.Once{}
-var droppedLabelsLogNextTimestamp uint64
+var droppedLabelsLogTicker = time.NewTicker(5 * time.Second)
 
 func labelsToString(labels []prompb.Label) string {
 	labelsCopy := append([]prompb.Label{}, labels...)