pixiv thumbnails

pixiv thumbnails

Tatsuhiko Kubo

 bokko@pixiv.com

Introduction to pixiv

● Illust Communication Site○ http://www.pixiv.net

● Users○ 5 million

● Monthly page view○ 3.3 billion

● Network Traffic○ Over 6Gbps

About me

● Tatsuhiko Kubo(H.N：bokko)● @cubicdaiya● Infrastructure & Software Engineer@pixiv. Inc

My Works@pixiv. Inc

Responsible for

● Middle-Ware Development● Technical Operation & Administration● Datastore & Caching Strategy● Image Upload & Transformation● Illust & User Recommendation● Notification( called Popboard at pixiv)

etc...

My works@private■Software

● neoagent○ A Yet Another Memcached Protocol Proxy Server

● dtl○ diff template library with C++

● ngx_small_light○ Dynamic Transformation Module for Nginx

■Writing● Software Design 2009 Sep

○ どのようにして差分を導き出すのか～diffの動作原理を知る～○ http://gihyo.jp/dev/column/01/prog/2011/diff_sd200906

And More -> http://cccis.jp

Agenda

● Following mechanism at pixiv○ Image Upload○ Thumbnail Generation

Scale of pixiv according to thumbnails

● pixiv has about 30,000,000 illusts and comics● Each illust has about 12 ～ too many thumbnails● 20,000 illusts and comics are uploaded every day● Total volume is about 30TB

Image Upload

Image Upload Detail 1

● Generate too many thumbnails○ 12 ～ too many thumbnails

● Save a original image and thumbnails to storage○ not NFS○ with in-house WebDAV Client(ImageClient)

ImageClient

WebDAV Client

ImageClient

Powered by @?????

ImageClient

Powered by @?????

ImageClient

Powered by @kamipo

ImageClient

● Enable WebDAV operations to multiple servers transparently○ put image○ delete image○ move image○ make directory○ move directory○ delete directory

ImageClient

Image Storage

Image Storage・・・・・

PUTDELETEMOVE

MKCOL

PUTDELETEMOVE

MKCOL

Image Upload Detail 2

● A image is uploaded semi-asynchronously○ Generating thumbnails takes a long time

File Selection View Input Information View Completed View

User Side Action

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

create lock file

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

create lock file

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

create lock file poll until lock file is deleted

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

Server Side Action

create lock file poll until lock file is deleted

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

Server Side Action

create lock file poll until lock file is deleted

prefork server

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

Server Side Action

create lock file poll until lock file is deleted

prefork server upload worker

upload worker

upload worker

prefork

semin-asynchronous upload mechanism

・・・・・

File Selection View Input Information View Completed View

User Side Action

Server Side Action

create lock file poll until lock file is deleted

prefork server upload worker

upload worker

upload worker

・・・・・

preforkGenrate Thumbnails

Genrate Thumbnails

Genrate Thumbnails

semin-asynchronous upload mechanism

File Selection View Input Information View Completed View

User Side Action

Server Side Action

create lock file poll until lock file is deleted

prefork server upload worker

upload worker

upload worker

・・・・・

preforkGenrate Thumbnails delete lock file

Genrate Thumbnails delete lock file

Genrate Thumbnails delete lock file

semin-asynchronous upload mechanism

Inside Image Upload

● User Side Action○ Apache○ PHP

■ ImageClient● Server Side Action

○ daemontools○ Python

■ python-prefork, python-q4m, python-worker● python-q4m and python-worker are in-house libraries

○ Q4M■ Used As Upload Job Queue

Thumbnail Generation

Two types of thumbnails at pixiv

● Static Thumbnail● Dynamic Thumbnail

Static Thumbnail

Static ThumbnailGenerated on upload

Detail of generating thumbnails

● pixiv uses ImageMagick○ ImageMagick is not fast○ But quality of generated image is good○ Quality is more important than speed for us○ Of course, optimization is important, too

ImageMagick Optimization

libjpeg-turbo

libjpeg-turbo

● Optimized libjpeg for x86 and x86_64● Replace libjpeg simply by LD_LIBRARY_PATH● ImageMagick uses libjpeg

benchmark of libjpeg and libjpeg-turbo

■libjpeg■libjpeg-turbo

processing JPEG-image with libjpeg and libjpeg-turbo

benchmark of libjpeg and libjpeg-turbo

libjpeg-turbo is faster than libjpeg by 10% on x86_64

■libjpeg■libjpeg-turbo

processing JPEG-image with libjpeg and libjpeg-turbo

Disable OpenMP

Disable OpenMP

● Latest ImageMagick is OpenMP enabled at default○ This is very slow in multi-process environment

● How to disable OpenMP○ Re-compile with '--disable-openmp'○ OMP_NUM_THREADS=1

● pixiv takes the latter○ Re-compiling and Re-packaging are complicated

OMP_NUM_THREADS=1

CPU Usage of Application Server

OMP_NUM_THREADS=1

CPU usage in peak dropped by 150～200%

CPU Usage of Application Server

OMP_NUM_THREADS=1

Load Average of Application Server

OMP_NUM_THREADS=1

Load Average became dust

Load Average of Application Server

Dynamic Thumbnail

Dynamic ThumbnailGenerated on demand

Why is dynamic thumbnail needed?

● Static thumbnail consumes disk space○ Dynamic thumbnail does not consume disk space

● Preparing new static thumbnails takes a long time○ Dynamic thumbnail is ready in a second！

Other Companies' Cases

● Cookpad○ mod_tofu○ http://www.slideshare.net/mirakui/ss-8150494

● livedoor(Now, NHN Japan)○ mod_small_light○ http://www.slideshare.net/livedoor/smalllight2

pixiv's Case

mod_small_light-1.1.1

mod_small_light-1.1.1

pixiv Edition5

mod_small_light-1.1.1

pixiv Edition5

heavily customized...

Heavily customized...

mod_small_light configuration

Resize image with mod_small_light

GET /small_light(dw=100,dh=100)/tank.jpgGET /tank.jpg

Many Options

q image quality(0～100)

of output format(jpg,gif,png,tiff)e processing engine(imlib2,imagemagick)

cc canvas colorp pattern name with SmallLightPatternDefine

etc Too many options

Pattern Name

Resize image with mod_small_light

GET /small_light(p=small)/tank.jpg orGET /tank.jpg

GET /small_light(dw=100,dh=100,e=imagemagick,jpeghint=y)/tank.jpg

Why not original mod_small_light?

● Some thumbnails are special○ comic cover○ various cropping algorithms depending on aspect ratio

● Default output format is JPEG○ It is good for us that input and output formats are the same

Why not original mod_small_light？

● No support for CMYK○ pixiv must support CMYK

● Needed support for strange aspect ratio○ da=l -> long-edge○ da=s -> short-edge○ da=p -> pixiv-edge (only pixiv Edition)

Special Thumbnail 1

● comic cover

Special Thumbnail 2

● special cropping algorithm

Special Thumbnail 2

● special cropping algorithm

Special Thumbnail 2

● special cropping algorithm

crop center of image if image is landscape

Special Thumbnail 3

● special cropping algorithm

Special Thumbnail 3

● special cropping algorithm

Special Thumbnail 3

● special cropping algorithm

crop top of image if image is portrait

Many Extend Options

rmprof remove image profilescrop_square crop image squarlycover add manga coversamec conform dw & dh & cw & chextendl extend long-edgeetc twenty new options in all

Summary

● Optimization of image processing is very important○ Generating thumbnail takes a long time○ Let's tune and desynchronize

● pixiv has two types of thumbnails○ Static Thumbnail○ Dynamic Thumbnail

● Dynamic Thumbnail is diskspace-saving and flexible○ Big image storage is expensive○ Easy to correspond to shift of application

■ New thumbnail types for new designs

Thanks！