lib/streamaggr: fix issue, when multiple flushes may occur with the same timestamp

docs/victoriametrics/changelog/CHANGELOG.md

@@ -28,6 +28,7 @@ See also [LTS releases](https://docs.victoriametrics.com/victoriametrics/lts-rel
 
 * BUGFIX: [stream aggregation](https://docs.victoriametrics.com/victoriametrics/stream-aggregation/): stop emitting stale values for `quantiles(...)` outputs when a time series has no samples during the current aggregation interval. Thanks to @alexei38 for the [pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/10918).
 * BUGFIX: [stream aggregation](https://docs.victoriametrics.com/victoriametrics/stream-aggregation/): extend delay on aggregation windows flush by the biggest lag among pushed samples. Before, the delay was calculated as 95th percentile across samples, which could underrepresent outliers and reject them from aggregation as "too old". See [#10402](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10402).
+* BUGFIX: [stream aggregation](https://docs.victoriametrics.com/victoriametrics/stream-aggregation/): address potential problem of multiple flushes occurring with an identical timestamp.
 
 ## [v1.143.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.143.0)
 

lib/streamaggr/deduplicator.go

@@ -231,6 +231,7 @@ func (d *Deduplicator) flush(pushFunc PushFunc) {
 		logger.Warnf("deduplication couldn't be finished in the configured dedupInterval=%s; it took %.03fs; "+
 			"possible solutions: increase dedupInterval; reduce samples' ingestion rate", d.interval, duration.Seconds())
 	}
+	deadlineTime = deadlineTime.Add(d.interval)
 	for time.Now().After(deadlineTime) {
 		deadlineTime = deadlineTime.Add(d.interval)
 	}

lib/streamaggr/streamaggr.go

@@ -845,6 +845,7 @@ func (a *aggregator) runFlusher(pushFunc PushFunc, alignFlushToInterval, skipFlu
 			} else {
 				a.flush(pf, flushTime, cs, false)
 			}
+			flushTime = flushTime.Add(a.interval)
 			for time.Now().After(flushTime) {
 				flushTime = flushTime.Add(a.interval)
 			}

lib/streamaggr/streamaggr_synctest_test.go

@@ -1,5 +1,3 @@
-//go:build synctest
-
 package streamaggr
 
 import (
@@ -485,10 +483,8 @@ foo 3.3
 `, ``, ``, ``, ``}, time.Minute, `foo:1m_count_series 1
 foo:1m_count_series{bar="baz"} 1
 foo:1m_sum_samples 0
-foo:1m_sum_samples 0
 foo:1m_sum_samples 4.3
 foo:1m_sum_samples{bar="baz"} 0
-foo:1m_sum_samples{bar="baz"} 0
 foo:1m_sum_samples{bar="baz"} 2
 foo:5m_by_bar_sum_samples 4.3
 foo:5m_by_bar_sum_samples{bar="baz"} 2
@@ -694,21 +690,29 @@ foo:1m_by_cde_rate_sum{cde="1"} 0.125
 
 	// test rate_sum and rate_avg, when two aggregation intervals are empty
 	f([]string{`
-foo{abc="123", cde="1"} 2
-foo{abc="456", cde="1"} 8
-foo{abc="777", cde="1"} 9 -10
+foo{abc="123", cde="1"} 1
+foo{abc="123", cde="1"} 2 1
+foo{abc="456", cde="1"} 7
+foo{abc="456", cde="1"} 8 1
+foo{abc="777", cde="1"} 8
+foo{abc="777", cde="1"} 9 1
 `, ``, ``, `
-foo{abc="123", cde="1"} 20
+foo{abc="123", cde="1"} 19
+foo{abc="123", cde="1"} 20 1
 foo{abc="456", cde="1"} 26
-foo{abc="777", cde="1"} 27 -10
-`}, time.Minute, `foo:1m_by_cde_rate_avg{cde="1"} 0.1
-foo:1m_by_cde_rate_sum{cde="1"} 0.2
+foo{abc="456", cde="1"} 27 1
+foo{abc="777", cde="1"} 27
+foo{abc="777", cde="1"} 28 1
+`}, time.Minute, `foo:1m_by_cde_rate_avg{cde="1"} 1
+foo:1m_by_cde_rate_avg{cde="1"} 1
+foo:1m_by_cde_rate_sum{cde="1"} 3
+foo:1m_by_cde_rate_sum{cde="1"} 3
 `, `            
 - interval: 1m
   by: [cde]
   outputs: [rate_sum, rate_avg]
   enable_windows: true
-`, "111111")
+`, "111111111111")
 
 	// rate_sum and rate_avg with duplicated events
 	f([]string{`