I was profiling the cpu usage of go/printer's only benchmark,
and found that token.File.Unpack was one of the top offenders.
It was mainly the deferred unlock that took a big chunk of time,
and to my surprise, reoving the use of defer helped significantly:
name old time/op new time/op delta
Print-16 5.61ms ± 2% 5.38ms ± 1% -4.04% (p=0.000 n=10+8)
name old speed new speed delta
Print-16 9.27MB/s ± 2% 9.64MB/s ± 1% +4.03% (p=0.000 n=9+8)
name old alloc/op new alloc/op delta
Print-16 332kB ± 0% 332kB ± 0% ~ (p=0.363 n=10+10)
name old allocs/op new allocs/op delta
Print-16 3.45k ± 0% 3.45k ± 0% ~ (all equal)
It seems like #38471 is to blame, as the defer prevents Unlock from
being inlined. Add a TODO as a reminder to come back here once the
compiler issue is fixed.
Change-Id: I5a1c6d36a8e8357435a305a1bc0970ee0358b08a
Reviewed-on: https://go-review.googlesource.com/c/go/+/424920 Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc> Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>