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 @ GolangUK 2017
Search
Filippo Valsorda
August 17, 2017
Programming
0
1.2k
You, latency and profiling @ GolangUK 2017
Filippo Valsorda
August 17, 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
410
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
2.8k
Encrypting the Internet with Go @ GopherCon 2017
filosottile
9
2.7k
You, latency and profiling @ GopherCon India 2017
filosottile
13
4.1k
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
bootcamp2025_バックエンド研修_WebAPIサーバ作成.pdf
geniee_inc
0
110
株式会社 Sun terras カンパニーデック
sunterras
0
320
SwiftDataを使って10万件のデータを読み書きする
akidon0000
0
120
Android16 Migration Stories ~Building a Pattern for Android OS upgrades~
reoandroider
0
110
XP, Testing and ninja testing ZOZ5
m_seki
3
680
TFLintカスタムプラグインで始める Terraformコード品質管理
bells17
2
180
バッチ処理を「状態の記録」から「事実の記録」へ
panda728
PRO
0
160
What's new in Spring Modulith?
olivergierke
1
150
CSC305 Lecture 04
javiergs
PRO
0
270
私はどうやって技術力を上げたのか
yusukebe
43
19k
私達はmodernize packageに夢を見るか feat. go/analysis, go/ast / Go Conference 2025
kaorumuta
2
570
Software Architecture
hschwentner
6
2.3k
Featured
See All Featured
Performance Is Good for Brains [We Love Speed 2024]
tammyeverts
12
1.2k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
162
15k
What's in a price? How to price your products and services
michaelherold
246
12k
Code Reviewing Like a Champion
maltzj
526
40k
JavaScript: Past, Present, and Future - NDC Porto 2020
reverentgeek
52
5.6k
Facilitating Awesome Meetings
lara
56
6.6k
Optimising Largest Contentful Paint
csswizardry
37
3.5k
Keith and Marios Guide to Fast Websites
keithpitt
411
23k
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
23
1.5k
Fantastic passwords and where to find them - at NoRuKo
philnash
52
3.4k
Building Better People: How to give real-time feedback that sticks.
wjessup
369
20k
The Illustrated Children's Guide to Kubernetes
chrisshort
49
51k
Transcript
You, latency and profiling Filippo Valsorda — @FiloSo/le
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 ms
A fast website… … can handle many requests … or
loads in a few milliseconds
A fast API… … can handle many clients … or
answers in a few milliseconds
Fast is… Throughput and Latency
CPU profiling -cpuprofile /debug/pprof/profile
SIGPROF CPU profiling
runtime/proc.go
h>p.Handler 1 Running on CPU h>p.Handler 2 I/O I/O h>p.Handler
3 I/O h>p.Handler 4 I/O CPU profiling
Running on CPU I/O I/O I/O I/O h>p.Handler 1 h>p.Handler
2 h>p.Handler 3 h>p.Handler 4 CPU profiling
I/O Observed latency h>p.Handler 1 CPU profiling
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 execuOon events: • gorouOne
scheduling, blocking • syscalls, network, I/O • garbage collecOon
•log files are BIG •25% overhead (aWer Go 1.7) •symbols
are embedded (Go 1.7) The tracer
•Full event context •GorouOne metadata and history •Discrete events, not
samples Trace vs. profile
CPU profiling Total: 20 samples
Tracing events
import "runtime/trace" import "net/http/pprof" /debug/pprof/trace?seconds=5 The tracer
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
-pprof=net
None
WriIng 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) }
tracefocus tracefocus -filter=ServeHTTP trace.out > net.pprof github.com/FiloSottile/tracetools
None
None
Build more tools! • Focus on gorouOne number • Aggregate
all blocking types • VisualizaOons • …
tracehist tracehist -filter=Close trace.out github.com/FiloSottile/tracetools
None
Build more tools! Profile latency!
QuesIons? Filippo Valsorda @FiloSo/le hi@filippo.io