tsdb: zero out Labels and memSeries pointers in pool (prometheus#13712)

bboreham · beorn7 · web-flow · commit bbe39af99f0a · 2024-03-06T13:36:34.000+01:00
* tsdb: zero out Labels and memSeries pointers in pool

So that the garbage-collector doesn't see this memory as still in use.

Signed-off-by: Bryan Boreham &lt;bjboreham@gmail.com&gt;

---------

Signed-off-by: Bryan Boreham &lt;bjboreham@gmail.com&gt;
Signed-off-by: Björn Rabenstein &lt;github@rabenste.in&gt;
Co-authored-by: Björn Rabenstein &lt;github@rabenste.in&gt;
diff --git a/tsdb/head_append.go b/tsdb/head_append.go
@@ -229,6 +229,9 @@ func (h *Head) putExemplarBuffer(b []exemplarWithSeriesRef) {
 	if b == nil {
 		return
 	}
+	for i := range b { // Zero out to avoid retaining label data.
+		b[i].exemplar.Labels = labels.EmptyLabels()
+	}
 
 	h.exemplarsPool.Put(b[:0])
 }
@@ -278,6 +281,9 @@ func (h *Head) getSeriesBuffer() []*memSeries {
 }
 
 func (h *Head) putSeriesBuffer(b []*memSeries) {
+	for i := range b { // Zero out to avoid retaining data.
+		b[i] = nil
+	}
 	h.seriesPool.Put(b[:0])
 }
 

Original file line number	Diff line number	Diff line change
`@@ -229,6 +229,9 @@ func (h *Head) putExemplarBuffer(b []exemplarWithSeriesRef) {`
`229`	`229`	`if b == nil {`
`230`	`230`	`return`
`231`	`231`	`}`
	`232`	`+ for i := range b { // Zero out to avoid retaining label data.`
	`233`	`+ b[i].exemplar.Labels = labels.EmptyLabels()`
	`234`	`+ }`
`232`	`235`
`233`	`236`	`h.exemplarsPool.Put(b[:0])`
`234`	`237`	`}`
`@@ -278,6 +281,9 @@ func (h Head) getSeriesBuffer() []memSeries {`
`278`	`281`	`}`
`279`	`282`
`280`	`283`	`func (h Head) putSeriesBuffer(b []memSeries) {`
	`284`	`+ for i := range b { // Zero out to avoid retaining data.`
	`285`	`+ b[i] = nil`
	`286`	`+ }`
`281`	`287`	`h.seriesPool.Put(b[:0])`
`282`	`288`	`}`
`283`	`289`