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
4k
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
2.1k
Le note cifrate di Antonio Marzi
filosottile
1
400
Why cgo is slow @ CapitalGo 2018
filosottile
2
4.6k
Squeezing a key through a carry bit @ 34c3
filosottile
0
1.7k
Calling Rust from Go, without cgo @ GothamGo 2017
filosottile
1
2.7k
You, latency and profiling @ GolangUK 2017
filosottile
0
1.2k
Encrypting the Internet with Go @ GopherCon 2017
filosottile
9
2.6k
TLS 1.3 @ 33c3
filosottile
4
6.9k
Stealing Bitcoin With Math - HOPE XI
filosottile
13
30k
Other Decks in Programming
See All in Programming
一人でAIプロダクトを作るための工夫 〜技術選定・開発プロセス編〜 / I want AI to work harder
rkaga
12
2.7k
AIエージェント開発、DevOps and LLMOps
ymd65536
1
120
なぜ今、Terraformの本を書いたのか? - 著者陣に聞く!『Terraformではじめる実践IaC』登壇資料
fufuhu
4
620
Webinar: AI-Powered Development: Transformiere deinen Workflow mit Coding Tools und MCP Servern
danielsogl
0
130
Portapad紹介プレゼンテーション
gotoumakakeru
1
130
画像コンペでのベースラインモデルの育て方
tattaka
3
1.7k
UbieのAIパートナーを支えるコンテキストエンジニアリング実践
syucream
2
490
Infer入門
riru
4
1.5k
ゲームの物理
fadis
5
1.2k
マイコンでもRustのtestがしたい その2/KernelVM Tokyo 18
tnishinaga
2
2.3k
Introduction to Git & GitHub
latte72
0
110
Understanding Kotlin Multiplatform
l2hyunwoo
0
260
Featured
See All Featured
Product Roadmaps are Hard
iamctodd
PRO
54
11k
Templates, Plugins, & Blocks: Oh My! Creating the theme that thinks of everything
marktimemedia
31
2.5k
Docker and Python
trallard
45
3.5k
StorybookのUI Testing Handbookを読んだ
zakiyama
30
6k
What's in a price? How to price your products and services
michaelherold
246
12k
VelocityConf: Rendering Performance Case Studies
addyosmani
332
24k
Design and Strategy: How to Deal with People Who Don’t "Get" Design
morganepeng
131
19k
Let's Do A Bunch of Simple Stuff to Make Websites Faster
chriscoyier
507
140k
The Pragmatic Product Professional
lauravandoore
36
6.8k
10 Git Anti Patterns You Should be Aware of
lemiorhan
PRO
656
60k
The Invisible Side of Design
smashingmag
301
51k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
161
15k
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