Yes, you are correct, if the template is only {{}}'s with no text then
there is no benefit, but no penalty, either (i.e., no down side in
performance). Once there is any reasonable amount of text (as all
templates I have written are), the speed up is noticeable.
-Paul
On Mon, Jul 11, 2016 at 12:46 PM, wrote:
> 1ms = 100ns. 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 10 12300 ns/op
>> BenchmarkNewR512-4 30 4513 ns/op
>> BenchmarkOldT512-4 10 23600 ns/op
>> BenchmarkNewT512-4 10 13898 ns/op
>> BenchmarkOldR8k-4 1133261 ns/op
>> BenchmarkNewR8k-4 10 14852 ns/op
>> BenchmarkOldT8k-45000264654 ns/op
>> BenchmarkNewT8k-4 1135056 ns/op
>> BenchmarkOldMany-4 300 5577909 ns/op
>> BenchmarkNewMany-4 300 5632914 ns/op
>>
>> BenchmarkOldR512-4 10 12100 ns/op
>> BenchmarkNewR512-4 30 4507 ns/op
>> BenchmarkOldT512-4 10 23297 ns/op
>> BenchmarkNewT512-4 10 14699 ns/op
>> BenchmarkOldR8k-4 1136474 ns/op
>> BenchmarkNewR8k-4 10 16566 ns/op
>> BenchmarkOldT8k-45000266256 ns/op
>> BenchmarkNewT8k-4 1137201 ns/op
>> BenchmarkOldMany-4 300 5606573 ns/op
>> BenchmarkNewMany-4 300 5596660 ns/op
>>
>> BenchmarkOldR512-4 10 12150 ns/op
>> BenchmarkNewR512-4 30 4405 ns/op
>> BenchmarkOldT512-4 10 21539 ns/op
>> BenchmarkNewT512-4 10 13735 ns/op
>> BenchmarkOldR8k-4 1133586 ns/op
>> BenchmarkNewR8k-4 10 14076 ns/op
>> BenchmarkOldT8k-45000264374 ns/op
>> BenchmarkNewT8k-4 1132618 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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