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Answer stability round 3: the allocation case of a read two levels under a pick holds at its baseline with no margin, as the performance gate decision now says

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Lilleman auf Larv
2026-10-06 13:23:08 +02:00
committed by Lillem4n
parent f07764bce1
commit fb3fb16deb
2 changed files with 11 additions and 7 deletions
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docs/decisions.md
+4
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@@ -398,6 +398,10 @@ CI load, while time varies with the machine and its neighbours. A rendering slow
almost always costs an allocation too (a lost pre-size, a per-item map, an extra copy).
The benchmark suite (the README's Development) reports time for a human, not as a pass/fail gate.
A case guarding against one allocation per render, such as a render's scope reaching the
heap through `pickKey.under`, holds at its baseline with no margin, since 10% of its
count is less than one allocation. Lilleman auf Larv decided it on 2026-10-06.
## Rows live in a TSV, the shape in JSON
2026-09-17, Lilleman auf Larv. Goals 8 and 13.
perf_test.go
+7 -7
View File
@@ -59,12 +59,12 @@ func TestNoRenderAllocRegression(t *testing.T) {
func TestNoReferenceAllocRegression(t *testing.T) {
word := `{"format":"{w}","w":["alpha","beta","gamma","delta"]}`
for _, s := range []struct {
name, json string
base float64
name, json string
base, slack float64
}{
{"a repeat of a reference path", `{"format":"{r}","r":{"format":"{/word.w}","repeat":20,"separator":", "}}`, 25},
{"a repeat of a name", `{"format":"{r}","r":{"format":"{/word as n}{n.w}{n.w}","repeat":20,"separator":", "}}`, 162},
{"a read two levels under a pick", `{"format":"{place.geo as g}{g} {g.town.zip}","place":{"format":"{geo}","geo":{"format":"{town.zip}","town":{"format":"{zip}","zip":"1"}}}}`, 12},
{"a repeat of a reference path", `{"format":"{r}","r":{"format":"{/word.w}","repeat":20,"separator":", "}}`, 25, 1.10},
{"a repeat of a name", `{"format":"{r}","r":{"format":"{/word as n}{n.w}{n.w}","repeat":20,"separator":", "}}`, 162, 1.10},
{"a read two levels under a pick", `{"format":"{place.geo as g}{g} {g.town.zip}","place":{"format":"{geo}","geo":{"format":"{town.zip}","town":{"format":"{zip}","zip":"1"}}}}`, 12, 1},
} {
f, err := New(WithoutShippedData(), WithDataFS(fstest.MapFS{
"word.json": {Data: []byte(word)},
@@ -73,8 +73,8 @@ func TestNoReferenceAllocRegression(t *testing.T) {
if err != nil {
t.Fatalf("New(%s): %v", s.name, err)
}
if allocs := testing.AllocsPerRun(10000, func() { f.Fake("x") }); allocs > s.base*1.10 {
t.Errorf("%s: %.1f allocs/op regressed past %.1f (baseline %.1f + 10%%); a render's scope reaching the heap is the usual cause", s.name, allocs, s.base*1.10, s.base)
if allocs := testing.AllocsPerRun(10000, func() { f.Fake("x") }); allocs > s.base*s.slack {
t.Errorf("%s: %.1f allocs/op regressed past %.1f (baseline %.1f × %.2f); a render's scope reaching the heap is the usual cause", s.name, allocs, s.base*s.slack, s.base, s.slack)
}
}
}