Trilha HPC TDC 2015: Mostramos quais são as principais vantagens e desvantagens da programação reativa. Atualmente existem algumas perguntas que ainda de fato não temos respostas: Será que nossos sistemas já estão no limite? Será que ainda há espaço a ser conquistado e ganhos de performance a se descobrir?

1. Reactive Programming: Brincando
com eficiência, composição e
assincronia.
Felipe Mamud
@ftmamud
Raphael Almeida
@raphait
HPC

2. Agradecimentos
HPC

3. Será que nossos sistemas já
estão no limite?

5. INTERNET USERS
2.4bi
2012
INTERNET USERS
3.01bi
TENS OF SERVERS
Fontes: http://recode.net/2014/05/28/meeker-as-internet-user-growth-slows-the-real-driver-is-mobile-usage/
http://www.slideshare.net/wearesocialsg/digital-social-mobile-in-2015
RESPONSE TIME
SECONDS
CLOUD-BASED CLUSTER
MULTICORE
OFFLINE
MAINTENANCE
REAL TIME
MILLISEC/MICROSEC
100%
UPTIME
FAST DATA
GIBABYTE DATA
BIGDATA
PETABYTES
2015

6. As exigências e as expectativas
para aplicações mudaram
drasticamente nos últimos anos.

7. Precisamos de sistemas que irão:
● Reagir a eventos (Event-Driven)
● Reagir a carga (Scalable)
● Reagir a falhas (Resilient)
● Reagir a usuários (Responsive)

8. Reactive Programming
“Readily responsive to a stimulus”

9. Reactive Manifesto

10. O que são sistemas Reativos?
Sistemas criados como Reativos são muito mais
flexíveis, desacoplados e escaláveis. Isso os torna
mais fáceis de desenvolver e manter. São mais
tolerantes a falhas e quando elas ocorrem são
tratadas com elegância ao invés de desastre.
Sistemas Reativos são responsivos, dando aos
usuários feedbacks mais interativos.
Fonte: http://www.reactivemanifesto.org/pt-BR

11. Reactive frameworks
Reactor
ReactiveX

12. Message-Driven
“Reactive Systems rely on asynchronous
message-passing”

13. Share Mutable State
● with threads:
○ code that is totally non-deterministic;
○ the root of all evil;
● Avoid it at all cost;
● Use immutability;

14. Never/Avoid Block
● Unless you really have to;
● Blocking kills scalability (+ performance);
● Use non-blocking IO;
● Use lock-free concurrency;

15. Async
● Use asynchronous event/message passing;
● Lower latency (vs sales);
● Better throughput;
● A more loosely coupled architecture, easier
to extend, evolve and maintain.

16. Some t ls
● Actors
● Agents
● Future/Dataflow
● Reactive Extensions (Rx)

17. Actors
● Isolated lightweight event-based processes;
● Each actor has a mailbox (message queue);
● Communicates through asynchronous and
non-blocking message passing;
● Location transparent (distributable);
● Supervision-based failure management;

18. Agents
● Reactive memory cells;
● Send a update function to the Agent;
● Reads are “free”, just dereferences
the Ref;
● Composes nicely;

19. Futures/Dataflow
● Allows you to spawn concurrent
computations and work with the not yet
computed results;
● Freely sharable;
● Allows non-blocking composition;
● Build in model for managing failure;

20. Reactive Extensions (Rx)
● Extend Futures with the concept of a
Stream;
● Composable in a type-safe way;
● Event-based & asynchronous;
● Observable ⇛ Push Collections;

21. Elastic
“Capable of being easily expanded or
upgraded on demand”

22. ● Mobile
● SQL Replication
● NoSQL DB
● Cloud Services
Distributed systems

23. What is the essence of
distributed computing?

24. What is the essence of distributed
computing?
1. Information travels at the speed of light;
2. Independent things fail independently.

25. Why necessary?
● Scalability;
● Availability;
● The network is unreliable;
● Location Transparency;

26. “Almost” no limit to scalability.
Shared Nothing
Assynchronous communication
Location Transparency
Loose Coupling

27. Resilience
“The ability of a substance or object to spring back into shape.”
“The capacity to recover quickly from difficulties.”

28. ● Exception in thread;
● Errors do not propagate between threads;
● Error handling tangled with business logic;
Failure recover

29. Right Way
● Isolate the failure;
● Compartmentalize;
● Manage failure locally;
● Avoid cascading failures;
● Supervision;

30. Responsive
“Quick to respond or react appropriately”

31. ● Latency consistent;
● Use Back Pressure;
● Smart Batching;
● Reative Request
(Async & Non-blocking Request & Response)
Responsive

33. Dúvidas?

34. THANK YOU!
FRIENDS TECHDAY
COMPARTILHAR, APRENDER E CONTRIBUIR!
Felipe Mamud
@ftmamud
Raphael Almeida
@raphait
We are a reactive family