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
400
Why cgo is slow @ CapitalGo 2018
filosottile
2
4.5k
Squeezing a key through a carry bit @ 34c3
filosottile
0
1.7k
Calling Rust from Go, without cgo @ GothamGo 2017
filosottile
1
2.7k
Encrypting the Internet with Go @ GopherCon 2017
filosottile
9
2.6k
You, latency and profiling @ GopherCon India 2017
filosottile
13
4k
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
Advanced Micro Frontends: Multi Version/ Framework Scenarios @WAD 2025, Berlin
manfredsteyer
PRO
0
370
Startups on Rails in Past, Present and Future–Irina Nazarova, RailsConf 2025
irinanazarova
0
200
Git Sync を超える!OSS で実現する CDK Pull 型デプロイ / Deploying CDK with PipeCD in Pull-style
tkikuc
4
240
ペアプロ × 生成AI 現場での実践と課題について / generative-ai-in-pair-programming
codmoninc
2
20k
Google Agent Development Kit でLINE Botを作ってみた
ymd65536
2
260
CDK引数設計道場100本ノック
badmintoncryer
2
360
『自分のデータだけ見せたい!』を叶える──Laravel × Casbin で複雑権限をスッキリ解きほぐす 25 分
akitotsukahara
2
650
脱Riverpod?fqueryで考える、TanStack Queryライクなアーキテクチャの可能性
ostk0069
0
340
AIともっと楽するE2Eテスト
myohei
8
2.9k
PHPでWebSocketサーバーを実装しよう2025
kubotak
0
310
Webの外へ飛び出せ NativePHPが切り拓くPHPの未来
takuyakatsusa
2
580
初学者でも今すぐできる、Claude Codeの生産性を10倍上げるTips
s4yuba
16
12k
Featured
See All Featured
Practical Orchestrator
shlominoach
189
11k
The Invisible Side of Design
smashingmag
301
51k
Stop Working from a Prison Cell
hatefulcrawdad
271
21k
Bash Introduction
62gerente
613
210k
Rails Girls Zürich Keynote
gr2m
95
14k
Making the Leap to Tech Lead
cromwellryan
134
9.4k
Designing Dashboards & Data Visualisations in Web Apps
destraynor
231
53k
[RailsConf 2023 Opening Keynote] The Magic of Rails
eileencodes
29
9.6k
Scaling GitHub
holman
460
140k
Learning to Love Humans: Emotional Interface Design
aarron
273
40k
Responsive Adventures: Dirty Tricks From The Dark Corners of Front-End
smashingmag
251
21k
Building an army of robots
kneath
306
45k
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