07a22bbc11
It used to be simple, and then it got complicated for speed (to reduce allocations, mostly), but that involved a mutex and hurt multi-core performance, contending on the mutex. A change was sent to try to improve that mutex contention in https://go-review.googlesource.com/c/42110/2/src/net/http/server.go but that introduced its own allocations (the string->interface{} boxing for the sync.Map key), which runs counter to the whole point of that statusLine function: to remove allocations. Instead, make the code simple again and not have a mutex. It's a bit slower for the single-core case, but nobody with a single-user HTTP server cares about 50 nanoseconds: name old time/op new time/op delta ResponseStatusLine 37.5ns ± 2% 87.1ns ± 2% +132.42% (p=0.029 n=4+4) ResponseStatusLine-2 63.1ns ± 1% 43.1ns ±12% -31.67% (p=0.029 n=4+4) ResponseStatusLine-4 53.8ns ± 8% 40.2ns ± 2% -25.29% (p=0.029 n=4+4) name old alloc/op new alloc/op delta ResponseStatusLine 0.00B ±NaN% 0.00B ±NaN% ~ (all samples are equal) ResponseStatusLine-2 0.00B ±NaN% 0.00B ±NaN% ~ (all samples are equal) ResponseStatusLine-4 0.00B ±NaN% 0.00B ±NaN% ~ (all samples are equal) name old allocs/op new allocs/op delta ResponseStatusLine 0.00 ±NaN% 0.00 ±NaN% ~ (all samples are equal) ResponseStatusLine-2 0.00 ±NaN% 0.00 ±NaN% ~ (all samples are equal) ResponseStatusLine-4 0.00 ±NaN% 0.00 ±NaN% ~ (all samples are equal) (Note the code could be even simpler with fmt.Fprintf, but that is relatively slow and involves a bunch of allocations getting arguments into interface{} for the call) Change-Id: I1fa119132dbbf97a8e7204ce3e0707d433060da2 Reviewed-on: https://go-review.googlesource.com/42133 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Bryan Mills <bcmills@google.com> |
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