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
strace(1) all the things!
Search
Dan Miller
November 13, 2014
Programming
3
640
strace(1) all the things!
Presented at the Marist College Computer Society meeting, 11/12/14
Dan Miller
November 13, 2014
Tweet
Share
More Decks by Dan Miller
See All by Dan Miller
Oh Snap!
jazzdan
0
290
HHVM at Etsy
jazzdan
22
6.9k
"API First" Development
jazzdan
7
1.1k
Other Decks in Programming
See All in Programming
Go言語の特性を活かした公式MCP SDKの設計
hond0413
1
180
WebエンジニアがSwiftをブラウザで動かすプレイグラウンドを作ってみた
ohmori_yusuke
0
170
Your Perfect Project Setup for Angular @BASTA! 2025 in Mainz
manfredsteyer
PRO
0
130
CSC509 Lecture 04
javiergs
PRO
0
300
iOSエンジニア向けの英語学習アプリを作る!
yukawashouhei
0
180
ИИ-Агенты в каждый дом – Алексей Порядин, PythoNN
sobolevn
0
150
そのpreloadは必要?見過ごされたpreloadが技術的負債として爆発した日
mugitti9
2
3k
CSC509 Lecture 06
javiergs
PRO
0
240
Railsだからできる 例外業務に禍根を残さない 設定設計パターン
ei_ei_eiichi
0
320
Local Peer-to-Peer APIはどのように使われていくのか?
hal_spidernight
2
450
非同期jobをtransaction内で 呼ぶなよ!絶対に呼ぶなよ!
alstrocrack
0
530
Le côté obscur des IA génératives
pascallemerrer
0
120
Featured
See All Featured
Imperfection Machines: The Place of Print at Facebook
scottboms
269
13k
ReactJS: Keep Simple. Everything can be a component!
pedronauck
667
120k
The Art of Delivering Value - GDevCon NA Keynote
reverentgeek
15
1.7k
Dealing with People You Can't Stand - Big Design 2015
cassininazir
367
27k
Understanding Cognitive Biases in Performance Measurement
bluesmoon
29
2.6k
The Pragmatic Product Professional
lauravandoore
36
6.9k
Principles of Awesome APIs and How to Build Them.
keavy
127
17k
GitHub's CSS Performance
jonrohan
1032
460k
How to Ace a Technical Interview
jacobian
280
24k
Easily Structure & Communicate Ideas using Wireframe
afnizarnur
194
16k
What's in a price? How to price your products and services
michaelherold
246
12k
Let's Do A Bunch of Simple Stuff to Make Websites Faster
chriscoyier
507
140k
Transcript
strace(1) all the things Dan Miller Software Engineer Etsy
etsy.com/careers
@jazzdan strace(1) all the things What is strace(1)? How to
see what a program does without the source A quick aside about man(1) pages How does ls(1) work?
What is strace?
@jazzdan strace(1) is a unix utility for observing system calls
How do we see what a program does without reading
the source?
@jazzdan $ls
@jazzdan $strace ls
None
@jazzdan strace ls • execve(2) • open(2) • close(2) •
getdents(2) • write(2)
A quick aside on Unix man pages
@jazzdan $man man
None
None
None
How does ls work?
execve("/bin/ls", ["ls"], [/* 23 vars */]) = 0
None
execve() executes the program pointed to by filename. filename must
be either a binary executable, or a script starting with a line of the form: ! #! interpreter [optional-arg]
int execve(const char *filename, char *const argv[], char *const envp[]);
open( “/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC ) = 3
None
Given a pathname for a file, open() returns a file
descriptor, a small, nonnegative integer for use in subsequent system calls (read(2), write(2), lseek(2), fcntl(2), etc.).
int open(const char *pathname, int flags)
open( “/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC ) = 3
@jazzdan Wait… what is libc?
@jazzdan $man libc
None
open( “.", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC ) = 3
getdents( 3, /* 4 entries */, 32768 ) = 712
None
int getdents(unsigned int fd, struct linux_dirent *dirp, unsigned int count);
getdents( 3, /* 23 entries */, 32768 )= 712
open( “.", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC ) = 3
close(3)
None
int close(int fd);
close(3)
write( 1, “hello_world\n", hello_world ) = 23
None
exit_group(0) = ?
None
This system call is equivalent to exit(2) except that it
terminates not only the calling thread, but all threads in the calling process's thread group.
void exit_group(int status);
@jazzdan When is strace(1) useful? • Anything involving files or
sockets • Path issues • See what is being sent over a network interface
@jazzdan When is strace(1) not useful? • In production (performance
is terrible) • When no syscalls are being executed
One Cool Trick for Performance Analysis (perf folks hate ‘em)
@jazzdan $strace -c ls
None
Questions?