1ms = 1000000ns. According to *Many results there is no gain.
понедельник, 11 июля 2016 г., 22:27:47 UTC+3 пользователь Paul Borman
написал:
>
> I was looking at text/template/parse/lex.go and noticed it seemed to be
> very inefficient in how it searched for {{ in its input. I rewrote lexText
> to us strings.Index rather than calling l.next() for every single rune in
> the string. The results were up to a 9x speed improvement, depending on
> the density of {{'s in the text.
>
> My results were:
>
> BenchmarkOldR512-4 100000 12300 ns/op
> BenchmarkNewR512-4 300000 4513 ns/op
> BenchmarkOldT512-4 100000 23600 ns/op
> BenchmarkNewT512-4 100000 13898 ns/op
> BenchmarkOldR8k-4 10000 133261 ns/op
> BenchmarkNewR8k-4 100000 14852 ns/op
> BenchmarkOldT8k-4 5000 264654 ns/op
> BenchmarkNewT8k-4 10000 135056 ns/op
> BenchmarkOldMany-4 300 5577909 ns/op
> BenchmarkNewMany-4 300 5632914 ns/op
>
> BenchmarkOldR512-4 100000 12100 ns/op
> BenchmarkNewR512-4 300000 4507 ns/op
> BenchmarkOldT512-4 100000 23297 ns/op
> BenchmarkNewT512-4 100000 14699 ns/op
> BenchmarkOldR8k-4 10000 136474 ns/op
> BenchmarkNewR8k-4 100000 16566 ns/op
> BenchmarkOldT8k-4 5000 266256 ns/op
> BenchmarkNewT8k-4 10000 137201 ns/op
> BenchmarkOldMany-4 300 5606573 ns/op
> BenchmarkNewMany-4 300 5596660 ns/op
>
> BenchmarkOldR512-4 100000 12150 ns/op
> BenchmarkNewR512-4 300000 4405 ns/op
> BenchmarkOldT512-4 100000 21539 ns/op
> BenchmarkNewT512-4 100000 13735 ns/op
> BenchmarkOldR8k-4 10000 133586 ns/op
> BenchmarkNewR8k-4 100000 14076 ns/op
> BenchmarkOldT8k-4 5000 264374 ns/op
> BenchmarkNewT8k-4 10000 132618 ns/op
> BenchmarkOldMany-4 300 5622040 ns/op
> BenchmarkNewMany-4 300 5638461 ns/op
>
>
> R512 was 512 bytes of Lorem Ipsum text with no {{}}'s
> R8K was 8,192 bytes of Lorem Ipsum text with no {{}}'s
>
> The T versions are the same, but with all occurrences of ipsum changed to
> {{.}}
> (3 times in T512 and 13 times in T8K).
>
> The Many version was the string "{{.}}" repeated 1000 times.
>
> The old code:
>
> for {
> delim, trimSpace := l.atLeftDelim()
> if delim {
> trimLength := Pos(0)
> if trimSpace {
> trimLength =
> rightTrimLength(l.input[l.start:l.pos])
> }
> l.pos -= trimLength
> if l.pos > l.start {
> l.emit(itemText)
> }
> l.pos += trimLength
> l.ignore()
> return lexLeftDelim
> }
> if l.next() == eof {
> break
> }
> }
>
>
> The new code:
>
> l.width = 0
> if x := strings.Index(l.input[l.pos:], l.leftDelim); x >= 0 {
> ldn := Pos(len(l.leftDelim))
> l.pos += Pos(x)
> trimLength := Pos(0)
> if strings.HasPrefix(l.input[l.pos+ldn:], leftTrimMarker) {
> trimLength =
> rightTrimLength(l.input[l.start:l.pos])
> }
> l.pos -= trimLength
> if l.pos > l.start {
> l.emit(itemText)
> }
> l.pos += trimLength
> l.ignore()
> return lexLeftDelim
> } else {
> l.pos = Pos(len(l.input))
> }
>
> Is this something that would be accepted into the standard library?
>
> Thanks,
>
> -Paul
>
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