mirror of https://github.com/golang/go.git
log/slog: optimize appendKey to reduce allocations
This change introduces a new method, `appendTwoStrings`, which
optimizes the `appendKey` function by avoiding the allocation of a
temporary string (string concatenation of prefix and key). Instead, it
directly appends the prefix and key to the buffer.
Additionally, added `BenchmarkAppendKey` benchmark tests to validate performance improvements.
This change improves performance in cases where large prefixes are used,
as verified by the following benchmarks:
goos: darwin
goarch: arm64
pkg: log/slog
cpu: Apple M1 Max
│ old.out │ new.out │
│ sec/op │ sec/op vs base │
AppendKey/prefix_size_5-10 44.41n ± 0% 35.62n ± 0% -19.80% (p=0.000 n=10)
AppendKey/prefix_size_10-10 48.17n ± 0% 39.12n ± 0% -18.80% (p=0.000 n=10)
AppendKey/prefix_size_30-10 84.50n ± 0% 62.30n ± 0% -26.28% (p=0.000 n=10)
AppendKey/prefix_size_50-10 124.9n ± 0% 102.3n ± 0% -18.09% (p=0.000 n=10)
AppendKey/prefix_size_100-10 203.6n ± 1% 168.7n ± 0% -17.14% (p=0.000 n=10)
geomean 85.61n 68.41n -20.09%
│ old.out │ new.out │
│ B/op │ B/op vs base │
AppendKey/prefix_size_5-10 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹
AppendKey/prefix_size_10-10 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹
AppendKey/prefix_size_30-10 48.00 ± 0% 0.00 ± 0% -100.00% (p=0.000 n=10)
AppendKey/prefix_size_50-10 128.00 ± 0% 64.00 ± 0% -50.00% (p=0.000 n=10)
AppendKey/prefix_size_100-10 224.0 ± 0% 112.0 ± 0% -50.00% (p=0.000 n=10)
geomean ² ? ² ³
¹ all samples are equal
² summaries must be >0 to compute geomean
³ ratios must be >0 to compute geomean
│ old.out │ new.out │
│ allocs/op │ allocs/op vs base │
AppendKey/prefix_size_5-10 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹
AppendKey/prefix_size_10-10 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=10) ¹
AppendKey/prefix_size_30-10 1.000 ± 0% 0.000 ± 0% -100.00% (p=0.000 n=10)
AppendKey/prefix_size_50-10 2.000 ± 0% 1.000 ± 0% -50.00% (p=0.000 n=10)
AppendKey/prefix_size_100-10 2.000 ± 0% 1.000 ± 0% -50.00% (p=0.000 n=10)
geomean ² ? ² ³
¹ all samples are equal
² summaries must be >0 to compute geomean
³ ratios must be >0 to compute geomean
This patch improves performance without altering the external behavior of the `slog` package.
Change-Id: I8b47718de522196f06e0ddac48af73e352d2e5cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/631415
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Aoang
Jonathan Amsterdam
parent
7e8ceadf85
commit
bec12f153a
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@ -525,8 +525,7 @@ func (s *handleState) appendError(err error) {
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func (s *handleState) appendKey(key string) {
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s.buf.WriteString(s.sep)
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if s.prefix != nil && len(*s.prefix) > 0 {
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// TODO: optimize by avoiding allocation.
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s.appendString(string(*s.prefix) + key)
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s.appendTwoStrings(string(*s.prefix), key)
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} else {
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s.appendString(key)
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}
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@ -538,6 +537,24 @@ func (s *handleState) appendKey(key string) {
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s.sep = s.h.attrSep()
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}
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// appendTwoStrings implements appendString(prefix + key), but faster.
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func (s *handleState) appendTwoStrings(x, y string) {
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buf := *s.buf
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switch {
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case s.h.json:
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buf.WriteByte('"')
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buf = appendEscapedJSONString(buf, x)
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buf = appendEscapedJSONString(buf, y)
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buf.WriteByte('"')
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case !needsQuoting(x) && !needsQuoting(y):
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buf.WriteString(x)
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buf.WriteString(y)
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default:
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buf = strconv.AppendQuote(buf, x+y)
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}
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*s.buf = buf
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}
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func (s *handleState) appendString(str string) {
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if s.h.json {
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s.buf.WriteByte('"')
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@ -10,7 +10,9 @@ import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"io"
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"log/slog/internal/buffer"
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"os"
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"path/filepath"
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"slices"
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@ -529,6 +531,20 @@ func TestJSONAndTextHandlers(t *testing.T) {
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wantText: "name.first=Perry name.last=Platypus",
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wantJSON: `{"name":{"first":"Perry","last":"Platypus"}}`,
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},
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{
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name: "group and key (or both) needs quoting",
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replace: removeKeys(TimeKey, LevelKey),
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attrs: []Attr{
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Group("prefix",
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String(" needs quoting ", "v"), String("NotNeedsQuoting", "v"),
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),
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Group("prefix needs quoting",
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String(" needs quoting ", "v"), String("NotNeedsQuoting", "v"),
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),
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},
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wantText: `msg=message "prefix. needs quoting "=v prefix.NotNeedsQuoting=v "prefix needs quoting. needs quoting "=v "prefix needs quoting.NotNeedsQuoting"=v`,
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wantJSON: `{"msg":"message","prefix":{" needs quoting ":"v","NotNeedsQuoting":"v"},"prefix needs quoting":{" needs quoting ":"v","NotNeedsQuoting":"v"}}`,
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},
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} {
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r := NewRecord(testTime, LevelInfo, "message", callerPC(2))
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line := strconv.Itoa(r.source().Line)
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@ -732,3 +748,31 @@ func TestDiscardHandler(t *testing.T) {
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l.Info("info", "a", []Attr{Int("i", 1)})
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l.Info("info", "a", GroupValue(Int("i", 1)))
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}
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func BenchmarkAppendKey(b *testing.B) {
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for _, size := range []int{5, 10, 30, 50, 100} {
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for _, quoting := range []string{"no_quoting", "pre_quoting", "key_quoting", "both_quoting"} {
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b.Run(fmt.Sprintf("%s_prefix_size_%d", quoting, size), func(b *testing.B) {
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var (
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hs = NewJSONHandler(io.Discard, nil).newHandleState(buffer.New(), false, "")
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prefix = bytes.Repeat([]byte("x"), size)
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key = "key"
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)
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if quoting == "pre_quoting" || quoting == "both_quoting" {
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prefix[0] = '"'
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}
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if quoting == "key_quoting" || quoting == "both_quoting" {
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key = "ke\""
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}
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hs.prefix = (*buffer.Buffer)(&prefix)
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for b.Loop() {
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hs.appendKey(key)
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hs.buf.Reset()
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}
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})
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}
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}
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}
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