Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
You, latency and profiling @ GopherCon India 2017
Search
Filippo Valsorda
February 25, 2017
Programming
13
3.9k
You, latency and profiling @ GopherCon India 2017
Filippo Valsorda
February 25, 2017
Tweet
Share
More Decks by Filippo Valsorda
See All by Filippo Valsorda
Asynchronous networking @ GopherCon 2018
filosottile
3
2k
Le note cifrate di Antonio Marzi
filosottile
1
350
Why cgo is slow @ CapitalGo 2018
filosottile
2
4.3k
Squeezing a key through a carry bit @ 34c3
filosottile
0
1.5k
Calling Rust from Go, without cgo @ GothamGo 2017
filosottile
1
2.6k
You, latency and profiling @ GolangUK 2017
filosottile
0
1.1k
Encrypting the Internet with Go @ GopherCon 2017
filosottile
9
2.6k
TLS 1.3 @ 33c3
filosottile
4
6.7k
Stealing Bitcoin With Math - HOPE XI
filosottile
13
30k
Other Decks in Programming
See All in Programming
テスト自動化失敗から再挑戦しチームにオーナーシップを委譲した話/STAC2024 macho
ma_cho29
1
1.3k
Webエンジニア主体のモバイルチームの 生産性を高く保つためにやったこと
igreenwood
0
330
Mermaid x AST x 生成AI = コードとドキュメントの完全同期への道
shibuyamizuho
0
160
今からはじめるAndroidアプリ開発 2024 / DevFest 2024
star_zero
0
1k
Jakarta EE meets AI
ivargrimstad
0
230
急成長期の品質とスピードを両立するフロントエンド技術基盤
soarteclab
0
920
これが俺の”自分戦略” プロセスを楽しんでいこう! - Developers CAREER Boost 2024
niftycorp
PRO
0
190
今年一番支援させていただいたのは認証系サービスでした
satoshi256kbyte
1
250
Stackless и stackful? Корутины и асинхронность в Go
lamodatech
0
660
複雑な仕様に立ち向かうアーキテクチャ
myohei
0
170
rails statsで大解剖 🔍 “B/43流” のRailsの育て方を歴史とともに振り返ります
shoheimitani
2
930
Асинхронность неизбежна: как мы проектировали сервис уведомлений
lamodatech
0
670
Featured
See All Featured
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
159
15k
The Art of Delivering Value - GDevCon NA Keynote
reverentgeek
8
1.2k
Rails Girls Zürich Keynote
gr2m
94
13k
Building a Scalable Design System with Sketch
lauravandoore
460
33k
Scaling GitHub
holman
458
140k
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
10
810
Faster Mobile Websites
deanohume
305
30k
Navigating Team Friction
lara
183
15k
Embracing the Ebb and Flow
colly
84
4.5k
How To Stay Up To Date on Web Technology
chriscoyier
789
250k
Learning to Love Humans: Emotional Interface Design
aarron
273
40k
Exploring the Power of Turbo Streams & Action Cable | RailsConf2023
kevinliebholz
28
4.4k
Transcript
You, latency and profiling Filippo Valsorda — @FiloSottile
What is fast?
A fast hash… … can hash many MB per second
A fast regex… … can process many MB/s
A fast database… … can store many GB per second
A fast database… … can store many GB per second
… or replies to queries in a few milliseconds
A fast website… … can handle many requests at the
same time … or loads in a few milliseconds
A fast API… … can handle many clients at the
same time … or answers in a few milliseconds
Fast is… Throughput and Latency
CPU profiling -cpuprofile /debug/pprof/profile
CPU profiling SIGPROF
runtime/proc.go
CPU profiling http.Handler 1 Running on CPU http.Handler 2 I/O
I/O http.Handler 3 I/O http.Handler 4 I/O
CPU profiling Running on CPU I/O I/O I/O I/O http.Handler
1 http.Handler 2 http.Handler 3 http.Handler 4
CPU profiling I/O Observed latency http.Handler 1
func Write(data []byte) { for i := 0; i <
50; i++ { tmpfile, _ := ioutil.TempFile("", "ex") defer os.Remove(tmpfile.Name()) _, err = tmpfile.Write(data) tmpfile.Close() } } func Hash(data []byte) { for i := 0; i < 50; i++ { sha256.Sum256(data) } }
$ time curl http://127.0.0.1:12345/hash-and-write 9.831 total go tool pprof -web
slowserver cpu.pprof
None
$ time curl http://127.0.0.1:12345/hash-and-write 9.831 total $ time
curl http://127.0.0.1:12345/write-no-hash 7.692 total
Latency is not all about CPU
CPU profiling is for throughput The tracer is for latency
$ time curl http://127.0.0.1:12345/write-no-hash 7.692 total go tool trace -pprof=syscall
trace.out > syscall.pprof go tool pprof -web syscall.pprof
None
The tracer Detailed nanosecond-level log of execution events: • goroutine
scheduling, blocking • syscalls, network, I/O • garbage collection
The tracer • log files are BIG • 25% overhead
(after Go 1.7) • symbols are embedded (Go 1.7)
Trace vs. profile • Full event context • Goroutine metadata
and history • Discrete events, not samples
The tracer import "runtime/trace" import "net/http/pprof" /debug/pprof/trace?seconds=5
None
go tool trace -pprof=TYPE trace.out Supported profile types are: -
net: network blocking profile - sync: synchronization blocking profile - syscall: syscall blocking profile - sched: scheduler latency profile
go tool trace -pprof=syscall trace.out > syscall.pprof go tool pprof
-web syscall.pprof
go tool trace -pprof=syscall trace.out > syscall.pprof go-torch -b syscall.pprof
&& open torch.svg
None
None
-pprof=syscall func Write(data []byte) { for i := 0; i
< 50; i++ { tmpfile, _ := ioutil.TempFile("", "ex") defer os.Remove(tmpfile.Name()) _, err = tmpfile.Write(data) tmpfile.Close() } }
-pprof=sync // Block waits on a channel func Block() {
<-time.After(1 * time.Second) }
-pprof=sync
-pprof=sync
-pprof=net func Download() []byte { r, err := http.Get("https://golang.org/doc/go1.8") body,
err := ioutil.ReadAll(r.Body) r.Body.Close() return body }
-pprof=net
-pprof=net
None
Writing our own profile prof := make(map[uint64]pprof.Record) for _, ev
:= range events { if ev.Type != trace.EvGoBlockNet { continue } rec := prof[ev.StkID] rec.Stk = ev.Stk rec.N++ rec.Time += ev.Link.Ts - ev.Ts prof[ev.StkID] = rec } pprof.BuildProfile(prof).Write(os.Stdout)
var childG = make(map[uint64]struct{}) var lastGLen int for { for
_, ev := range events { if ev.Type != trace.EvGoCreate { continue } if _, ok := childG[ev.G]; !ok && !filterStack(ev.Stk, re) { continue } childG[ev.Args[0]] = struct{}{} } if len(childG) == lastGLen { break } lastGLen = len(childG) }
if _, ok := childG[ev.G]; !ok && !filterStack(ev.Stk, re) {
continue }
tracefocus tracefocus -filter=ServeHTTP trace.out > net.pprof github.com/FiloSottile/tracetools
None
None
Build more tools! • Focus on goroutine number • Aggregate
all blocking types • Visualizations • …
tracehist tracehist -filter=Close trace.out github.com/FiloSottile/tracetools
None
Build more tools! Profile latency!
Questions? Filippo Valsorda @FiloSottile filippo@cloudflare.com