Zalo Real-time System: Architecture

& ExperienceBy Nguyen Quang Nam

Zing Senior Software Manager

Web-Technical

Content

• About Zalo• Technology in Zalo• Real-time System Architecture• Experience• Q&A

About Zalo

Features

• Communication: message (voice, text), call• Social: “Nhật ký”, “Phòng trò chuyện”

Communication

Social

Updated stat

• Users: 3.0M total• Messages: 30M per day

Technology in Zalo

Technology

• Programming languages: C/C++ and Java for services at server-side• Client platforms: IOS, Android, Symbian (S40, S60),

Windows Phone (soon)

Technology (cont)

Connection servers are key points of the Zalo real-time system

Free / Opensource Inhouse

Load balancing HA proxy ZaCacheProxy, ZaRouter

Web servers Ngnix, Jetty ZaHttp

Searching Elastic, Solr Prefix Search Service

Database PostgreSQL, MySQL ZaDB, List32, List64, …

Connection servers ZaCommServer, ZEventbus

Real-time System Architecture

N-Tier

ZaCommServer

ZaCommServer (cont)

• Programming language: C/C• IO event mechanism: Epoll (libevent)• Binary protocol with authenticated connections &

encrypted messages

ZaCommServer (cont)

• Capacity per one box:• 1M concurrent connections tested• 200K throughput messages per second

Experience

Break the thing into multi-layers andlet they be independent each other

Move biz out of high performance services

Lessons Zalo learned

• Http long polling is not a good choice for a good app• Do not spend much time in optimizing small data• Memory fragment is a really big trouble in high

performance services, develop our own memory allocator lib instead of using default system glibc

Q&A

Contact: Nguyen Quang Nam namnq@vng.com.vn

http://me.zing.vn/nam.nq