Closed
Description
Commit 672729e (https://golang.org/cl/37879) introduced performance regression for "no such host" case.
goos: linux
goarch: amd64
pkg: net
BenchmarkGoLookupIPNoSuchHost-4 30 43958216 ns/op
BenchmarkGoLookupIPNoSuchHost-4 30 43639313 ns/op
BenchmarkGoLookupIPNoSuchHost-4 30 58653180 ns/op
BenchmarkGoLookupIPNoSuchHost-4 30 49881501 ns/op
BenchmarkGoLookupIPNoSuchHost-4 30 52573745 ns/op
Before that commit:
goos: linux
goarch: amd64
pkg: net
BenchmarkGoLookupIPNoSuchHost-4 2000 681589 ns/op
BenchmarkGoLookupIPNoSuchHost-4 2000 717598 ns/op
BenchmarkGoLookupIPNoSuchHost-4 2000 688904 ns/op
BenchmarkGoLookupIPNoSuchHost-4 2000 690374 ns/op
BenchmarkGoLookupIPNoSuchHost-4 2000 780634 ns/op
In other words:
name old time/op new time/op delta
GoLookupIPNoSuchHost-4 712µs ±10% 53484µs ±11% +7413.71% (p=0.008 n=5+5)
Needs investigation.