From: ShiKaiWi Date: Sun, 14 Apr 2019 17:09:40 +0000 (+0000) Subject: expvar: improve Map.addKey for large number of keys X-Git-Tag: go1.13beta1~672 X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=518ee55d7814a1de66ec9e2fb4829711cc63d0aa;p=gostls13.git expvar: improve Map.addKey for large number of keys The existing implementation has poor performance for inserting large number of keys because it chooses to append the new key to the sorted keys array and then sort the new array again (time complexity is O(nlogn)). The improvement tries to utilize the sorted keys array by searching the index and doing an insertion if any (time complexity is O(logn)). Benchmarked on 4-core machine with `go test -cpu 1,2,4,8 -count 5 -benchmem -bench=.`(the equal results are omitted): name old time/op new time/op delta MapAddDifferentRandom-8 408µs ±11% 69µs ± 3% -82.95% (p=0.008 n=5+5) MapAddDifferentRandom-4 389µs ±19% 69µs ± 2% -82.28% (p=0.008 n=5+5) MapAddDifferentRandom-2 365µs ± 4% 75µs ± 6% -79.51% (p=0.008 n=5+5) MapSetDifferentRandom-8 365µs ± 4% 76µs ±40% -79.07% (p=0.008 n=5+5) MapAddDifferentRandom 366µs ± 3% 78µs ± 6% -78.66% (p=0.008 n=5+5) MapSetDifferentRandom 369µs ± 2% 81µs ±34% -77.99% (p=0.008 n=5+5) MapSetDifferentRandom-2 378µs ±10% 100µs ±32% -73.47% (p=0.008 n=5+5) MapSetDifferentRandom-4 352µs ± 4% 108µs ± 7% -69.40% (p=0.008 n=5+5) IntAdd-2 23.1ns ±21% 15.5ns ±23% -32.79% (p=0.032 n=5+5) IntSet-2 21.4ns ±14% 16.7ns ±17% -22.00% (p=0.016 n=5+5) FloatAdd-8 88.8ns ± 9% 70.8ns ±25% -20.23% (p=0.024 n=5+5) FloatSet-2 22.3ns ±15% 17.8ns ±14% -20.14% (p=0.008 n=5+5) IntAdd-8 21.7ns ± 3% 18.7ns ± 4% -14.00% (p=0.008 n=5+5) MapAddDifferent-8 1.58µs ± 7% 1.42µs ± 6% -10.06% (p=0.016 n=5+5) StringSet-2 42.4ns ± 1% 43.7ns ± 5% +3.07% (p=0.048 n=4+5) FloatSet 8.27ns ± 2% 8.60ns ± 1% +3.94% (p=0.008 n=5+5) FloatAdd 12.5ns ± 2% 13.0ns ± 4% +4.33% (p=0.032 n=5+5) MapSetString-4 94.6ns ± 0% 101.7ns ± 4% +7.55% (p=0.016 n=4+5) MapAddSameSteadyState-2 34.9ns ± 3% 37.7ns ± 5% +8.14% (p=0.008 n=5+5) StringSet-4 34.5ns ± 0% 37.6ns ± 9% +9.02% (p=0.016 n=4+5) MapSetDifferent-8 377ns ± 3% 411ns ± 7% +9.07% (p=0.008 n=5+5) MapAddSameSteadyState 39.1ns ± 2% 42.8ns ± 6% +9.36% (p=0.008 n=5+5) MapAddDifferentSteadyState 172ns ± 4% 190ns ± 9% +10.96% (p=0.016 n=5+5) MapSet 143ns ± 4% 159ns ± 2% +11.06% (p=0.008 n=5+5) MapSet-4 96.9ns ± 5% 107.8ns ± 6% +11.25% (p=0.008 n=5+5) MapSet-2 102ns ± 6% 114ns ± 8% +11.94% (p=0.008 n=5+5) IntSet 8.18ns ± 1% 12.78ns ±13% +56.31% (p=0.008 n=5+5) name old alloc/op new alloc/op delta MapSetDifferentRandom-4 19.8kB ± 0% 16.6kB ± 0% -16.21% (p=0.008 n=5+5) MapSetDifferentRandom 19.8kB ± 0% 16.6kB ± 0% -16.21% (p=0.008 n=5+5) MapSetDifferentRandom-8 19.8kB ± 0% 16.6kB ± 0% -16.20% (p=0.008 n=5+5) MapSetDifferentRandom-2 19.8kB ± 0% 16.6kB ± 0% -16.20% (p=0.008 n=5+5) MapAddDifferentRandom 20.6kB ± 0% 17.4kB ± 0% -15.57% (p=0.008 n=5+5) MapAddDifferentRandom-8 20.6kB ± 0% 17.4kB ± 0% -15.57% (p=0.008 n=5+5) MapAddDifferentRandom-2 20.6kB ± 0% 17.4kB ± 0% -15.56% (p=0.008 n=5+5) MapAddDifferentRandom-4 20.6kB ± 0% 17.4kB ± 0% -15.56% (p=0.008 n=5+5) MapAddDifferent 1.09kB ± 0% 0.96kB ± 0% -11.76% (p=0.008 n=5+5) MapAddDifferent-2 1.09kB ± 0% 0.96kB ± 0% -11.76% (p=0.008 n=5+5) MapAddDifferent-4 1.09kB ± 0% 0.96kB ± 0% -11.76% (p=0.008 n=5+5) MapAddDifferent-8 1.09kB ± 0% 0.96kB ± 0% -11.76% (p=0.008 n=5+5) MapAddSame 480B ± 0% 448B ± 0% -6.67% (p=0.008 n=5+5) MapAddSame-2 480B ± 0% 448B ± 0% -6.67% (p=0.008 n=5+5) MapAddSame-4 480B ± 0% 448B ± 0% -6.67% (p=0.008 n=5+5) MapAddSame-8 480B ± 0% 448B ± 0% -6.67% (p=0.008 n=5+5) name old allocs/op new allocs/op delta MapSetDifferentRandom 423 ± 0% 323 ± 0% -23.64% (p=0.008 n=5+5) MapSetDifferentRandom-2 423 ± 0% 323 ± 0% -23.64% (p=0.008 n=5+5) MapSetDifferentRandom-4 423 ± 0% 323 ± 0% -23.64% (p=0.008 n=5+5) MapSetDifferentRandom-8 423 ± 0% 323 ± 0% -23.64% (p=0.008 n=5+5) MapAddDifferentRandom 523 ± 0% 423 ± 0% -19.12% (p=0.008 n=5+5) MapAddDifferentRandom-2 523 ± 0% 423 ± 0% -19.12% (p=0.008 n=5+5) MapAddDifferentRandom-4 523 ± 0% 423 ± 0% -19.12% (p=0.008 n=5+5) MapAddDifferentRandom-8 523 ± 0% 423 ± 0% -19.12% (p=0.008 n=5+5) MapAddDifferent 31.0 ± 0% 27.0 ± 0% -12.90% (p=0.008 n=5+5) MapAddDifferent-2 31.0 ± 0% 27.0 ± 0% -12.90% (p=0.008 n=5+5) MapAddDifferent-4 31.0 ± 0% 27.0 ± 0% -12.90% (p=0.008 n=5+5) MapAddDifferent-8 31.0 ± 0% 27.0 ± 0% -12.90% (p=0.008 n=5+5) MapAddSame 11.0 ± 0% 10.0 ± 0% -9.09% (p=0.008 n=5+5) MapAddSame-2 11.0 ± 0% 10.0 ± 0% -9.09% (p=0.008 n=5+5) MapAddSame-4 11.0 ± 0% 10.0 ± 0% -9.09% (p=0.008 n=5+5) MapAddSame-8 11.0 ± 0% 10.0 ± 0% -9.09% (p=0.008 n=5+5) Fixes #31414 Change-Id: I2dd655dec9dbbf8d7881a0f3f8edcb3d29199a48 GitHub-Last-Rev: a816fe3f62498481500a0ce9695de9fd3aa9f7b7 GitHub-Pull-Request: golang/go#31418 Reviewed-on: https://go-review.googlesource.com/c/go/+/171718 Run-TryBot: Brad Fitzpatrick TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick --- diff --git a/src/expvar/expvar.go b/src/expvar/expvar.go index 976b300d63..c0dc0532b1 100644 --- a/src/expvar/expvar.go +++ b/src/expvar/expvar.go @@ -141,8 +141,14 @@ func (v *Map) Init() *Map { func (v *Map) addKey(key string) { v.keysMu.Lock() defer v.keysMu.Unlock() - v.keys = append(v.keys, key) - sort.Strings(v.keys) + // Using insertion sort to place key into the already-sorted v.keys. + if i := sort.SearchStrings(v.keys, key); i >= len(v.keys) { + v.keys = append(v.keys, key) + } else if v.keys[i] != key { + v.keys = append(v.keys, "") + copy(v.keys[i+1:], v.keys[i:]) + v.keys[i] = key + } } func (v *Map) Get(key string) Var { diff --git a/src/expvar/expvar_test.go b/src/expvar/expvar_test.go index 804b56c1aa..7b1f83a7d7 100644 --- a/src/expvar/expvar_test.go +++ b/src/expvar/expvar_test.go @@ -6,6 +6,7 @@ package expvar import ( "bytes" + "crypto/sha1" "encoding/json" "fmt" "net" @@ -299,6 +300,26 @@ func BenchmarkMapSetDifferent(b *testing.B) { }) } +// BenchmarkMapSetDifferentRandom simulates such a case where the concerned +// keys of Map.Set are generated dynamically and as a result insertion is +// out of order and the number of the keys may be large. +func BenchmarkMapSetDifferentRandom(b *testing.B) { + keys := make([]string, 100) + for i := range keys { + keys[i] = fmt.Sprintf("%x", sha1.Sum([]byte(fmt.Sprint(i)))) + } + + v := new(Int) + b.ResetTimer() + + for i := 0; i < b.N; i++ { + m := new(Map).Init() + for _, k := range keys { + m.Set(k, v) + } + } +} + func BenchmarkMapSetString(b *testing.B) { m := new(Map).Init() @@ -350,6 +371,25 @@ func BenchmarkMapAddDifferent(b *testing.B) { }) } +// BenchmarkMapAddDifferentRandom simulates such a case where that the concerned +// keys of Map.Add are generated dynamically and as a result insertion is out of +// order and the number of the keys may be large. +func BenchmarkMapAddDifferentRandom(b *testing.B) { + keys := make([]string, 100) + for i := range keys { + keys[i] = fmt.Sprintf("%x", sha1.Sum([]byte(fmt.Sprint(i)))) + } + + b.ResetTimer() + + for i := 0; i < b.N; i++ { + m := new(Map).Init() + for _, k := range keys { + m.Add(k, 1) + } + } +} + func BenchmarkMapAddSameSteadyState(b *testing.B) { m := new(Map).Init() b.RunParallel(func(pb *testing.PB) {