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fix: do not repair Go profiles with deeply recursive stacks #3052

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merged 1 commit into from
Feb 28, 2024
Merged

fix: do not repair Go profiles with deeply recursive stacks #3052

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21 changes: 14 additions & 7 deletions pkg/pprof/fix_go_heap_truncated.go
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Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,8 @@ func RepairGoHeapTruncatedStacktraces(p *profilev1.Profile) {
if !ok || j > c.off {
// This group has more complete stack traces:
m[k] = group{
gid: uint32(i),
// gid 0 is reserved as a sentinel value.
gid: uint32(i + 1),
off: j,
}
}
Expand All @@ -137,14 +138,14 @@ func RepairGoHeapTruncatedStacktraces(p *profilev1.Profile) {
//
// Dependencies:
// - group i depends on d[i].
// - d[i] depends on d[d[i].gid].
// - d[i] depends on d[d[i].gid-1].
d := make([]group, len(groups))
for i := 0; i < len(groups); i++ {
g := groups[i]
t := topToken(samples[g].LocationId)
k := unsafeString(t)
c, ok := m[k]
if !ok || c.off == 0 || groups[c.gid] == g {
if !ok || c.gid-1 == uint32(i) {
// The current group has the most complete stack trace.
continue
}
Expand All @@ -159,21 +160,27 @@ func RepairGoHeapTruncatedStacktraces(p *profilev1.Profile) {
g := groups[i]
c := d[i]
var off uint32
for c.off > 0 {
var j int
for c.gid > 0 && c.off > 0 {
off += c.off
n := d[c.gid]
if n.off == 0 {
n := d[c.gid-1]
if n.gid == 0 || c.off == 0 {
// Stop early to preserve c.
break
}
c = n
j++
if j == tokenLen {
// Profiles with deeply recursive stack traces are ignored.
return
}
}
if off == 0 {
// The current group has the most complete stack trace.
continue
}
// The reference stack trace.
appx := samples[groups[c.gid]].LocationId
appx := samples[groups[c.gid-1]].LocationId
// It's possible that the reference stack trace does not
// include the part we're looking for. In this case, we
// simply ignore the group. Although it's possible to infer
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