Make printing faster by avoiding mallocs and some other advances.
Roughly 33% faster for simple cases, probably more for complex ones.
Before:
mallocs per Sprintf(""): 4
mallocs per Sprintf("xxx"): 6
mallocs per Sprintf("%x"): 10
mallocs per Sprintf("%x %x"): 12
Now:
mallocs per Sprintf(""): 2
mallocs per Sprintf("xxx"): 3
mallocs per Sprintf("%x"): 5
mallocs per Sprintf("%x %x"): 7
Speed improves because of avoiding mallocs and also by sharing a bytes.Buffer
between print.go and format.go rather than copying the data back after each
printed item.
Before:
fmt_test.BenchmarkSprintfEmpty
1000000 1346 ns/op
fmt_test.BenchmarkSprintfString 500000 3461 ns/op
fmt_test.BenchmarkSprintfInt 500000 3671 ns/op
Now:
fmt_test.BenchmarkSprintfEmpty
2000000 995 ns/op
fmt_test.BenchmarkSprintfString
1000000 2745 ns/op
fmt_test.BenchmarkSprintfInt
1000000 2391 ns/op
fmt_test.BenchmarkSprintfIntInt 500000 3751 ns/op
I believe there is more to get but this is a good milestone.
R=rsc
CC=golang-dev, hong
https://golang.org/cl/166076