Web-Services in C++ Building fast, memory-efficient and maintainable web-services in C++ Maximilian Haupt MUC /06/30

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1 Web-Services in C++ Building fast, memory-efficient and maintainable web-services in C++ Maximilian Haupt MUC /06/30

2 Background Professional C/C++ developer since 2006 VR, Real-Time Audio, Game-Engine, Big-Data, Machine-Learning

3 When talking about web-services Plain REST-like HTTP APIs talking JSON a.k.a. Micro-Services No fully fledged web-stack à Ruby on Rails, Django, MEAN, No static file serving à nginx/apache No reverse proxy / load balancing à nginx/haproxy No SSL termination à nginx/haproxy No template rendering à frontend (Angular, React, )

4 RTB detour

5 mbr targeting bidder wrap-up Started as a research project written in python Small RTBkit Intermezzo Later, rewritten in node.js Performance issues due to increasing traffic

6 rtb stack before HTTP nginx Graphite HTTP bidder DB/ Cache Logging

7 rtb stack after HTTP nginx HTTP Graphite broker ZeroMQ (CBFC) bidder DB/ Cache Logging

8 More than HTTP Proxygen: lwan: Wt: http-parser: httpp: - Hi Thomas! :) served: libevhtp:

9 JSON JsonCpp RapidJSON Json11 yajl gason ArduinoJson For a more complete list, e.g.:

10 TODO: put some nice broker graphs here Linux, C++14 (g++ 4.8), boost::asio, httpp, JsonCpp, ZeroMQ, tcmalloc, Intel TBB Routing (expensive stuff) Adx/Adscale/ Adx/Adscale/ Request Augmentation Timeout Response Sanity Checks ZeroMQ + JSON JSON Dispatch

11 Btw: use latest JsonCpp and link it statically!

12 Broker evolution Augmentation with additional data Logging to Kafka QoS, load balancing, rate limiting Data scientists love data, i.e. traffic

13 JSON love & hate

14 Schemas to the rescue JsonSchema helps. a bit. maybe Typos are still an issue Knowledge about types still spread throughout the code Still accessing json members through strings Start writing you own serialization Structs plus hand-crafted de-/serialization code

15 Protobuf to the rescue!!!11elf

16 Protobuf to the rescue!!!11elf generated Classes

17 Protobuf to the rescue!!!11elf Reflection

18 Protobuf to the rescue!!!11elf Serialization

19 Protobuf to the rescue!!!11elf Message::Clear()

20 Protobuf to the rescue!!!11elf Documentation Thanks Google: openrtb.proto (github.com/google/openrtb)

21 Json to protobuf and back json-protobuf mapper using the generated reflection (RapidJSON based) (jansson based) (jansson based) (Java) (node.js) à Single place for schema validation and performance improvements

22 Json to protobuf and back

23 Drop the bass response times

24 Now ~3 billion requests/day

25 Let it sink

26 Use protobuf for all data structures!

27 Sky is the limit Still more memory used than needed (raw buffer + json + protobuf) Use event-based json parser (e.g. yajl or RapidJson) for memory-efficiency Get rid of reflection by also generating parser code

28 Generate json state machine from proto file <number> { key:"a" 2 null } key:"b" { key:"c" <string> }

29 protog A protobuf json-parser generator! $ protoc --cpp_out=. openrtb.proto $ protog -p openrtb.proto -i openrtb.pb.h \ -m com.google.openrtb.bidrequest Will generate openrtb.pb.{cc,h} and bidrequest_parser.pb.{cc,h}

30 Disclaimer protog is not ready for production! Prototype which contains bugs Does not support self-referencing messages Many rough edges

31 Benchmark preface Never trust benchmarks other people present to you Highly recommend Brendan Gregg s talks and blog: brendangregg.com All code is online: github.com/0x7f/cpp-meetup

32 httpp (raw) proxygen (raw) httpp + ganson httpp + protog httpp + jsoncpp httpp + rapidjson httpp + pbjson nodejs (raw) node.js + JSON node.js + ajv httpp + rapidjson + validation 0 0,5 1 1,5 2 2,5 3 EC2 c4.4xlarge (14.04 LTS), 4 threads, wrk(c=200,t=12,d=60s), POST bidrequest.2.json (~1.5kb)

34 There is no silver bullet Serialization vs meat Large vs small JSON Multi-purpose backend vs single task Green field vs existing code Standalone vs embedded http server Normal vs high throughput Hard memory constraints

35 Summary Measure! Measure! Measure! Web-services are more than HTTP+JSON Mastering JSON is hard Schemas and generated code helps C++ can be very fast when used correctly Which library/tool for which use-case

36 Thank you!

37 Questions? Maximilian Haupt github.com/0x7f

Web-Services in C++ Building fast, memory-efficient and maintainable web-services in C++ Maximilian Haupt C++ Meetup 2016/05/17

Web-Services in C++ Building fast, memory-efficient and maintainable web-services in C++ Maximilian Haupt C++ Meetup 2016/05/17 Summary The talk will cover best-practices and utilities for building fast