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lib/promscrape: make consistent scrape time offsets across reloads for the same ScrapeURL and Labels

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This should make consistent intervals between data points for scrape targets across reloads.
Previously these intervals were random.
This commit is contained in:
Aliaksandr Valialkin 2020-05-03 14:29:26 +03:00
parent f25416984b
commit ab1e6a76bb
1 changed files with 16 additions and 5 deletions
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21
lib/promscrape/scrapework.go
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@ -3,7 +3,6 @@ package promscrape
import (
"flag"
"fmt"
"math/rand"
"strings"
"time"
@ -14,6 +13,7 @@ import (
"github.com/VictoriaMetrics/VictoriaMetrics/lib/promrelabel"
parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
"github.com/VictoriaMetrics/metrics"
xxhash "github.com/cespare/xxhash/v2"
)
var (
@ -121,11 +121,22 @@ type scrapeWork struct {
}
func (sw *scrapeWork) run(stopCh <-chan struct{}) {
// Randomize start time for the first scrape in order to spread load
// when scraping many targets.
// Calculate start time for the first scrape from ScrapeURL and labels.
// This should spread load when scraping many targets with different
// scrape urls and labels.
// This also makes consistent scrape times across restarts
// for a target with the same ScrapeURL and labels.
scrapeInterval := sw.Config.ScrapeInterval
randSleep := time.Duration(float64(scrapeInterval) * rand.Float64())
timer := time.NewTimer(randSleep)
key := fmt.Sprintf("ScrapeURL=%s, Labels=%s", sw.Config.ScrapeURL, sw.Config.LabelsString())
h := uint32(xxhash.Sum64([]byte(key)))
randSleep := uint64(float64(scrapeInterval) * (float64(h) / (1 << 32)))
sleepOffset := uint64(time.Now().UnixNano()) % uint64(scrapeInterval)
logger.Infof("randsleep=%d, sleepOffset=%d", randSleep, sleepOffset)
if randSleep < sleepOffset {
randSleep += uint64(scrapeInterval)
}
randSleep -= sleepOffset
timer := time.NewTimer(time.Duration(randSleep))
var timestamp int64
var ticker *time.Ticker
select {