Fault-Tolerant Clients: Escrevendo Clients e Services Tolerantes a Falhas

Com a moda de microservices a industria de software voltou a favorecer o desenvolvimento de sistemas altamente distribuídos, o que possibilitou melhorar a cadência nas entregas dos times e também escalar componentes de maneira independente e isolada. Apesar das vantagens, muitos trade-offs foram colocados na mesa, agora o desenvolvedor precisa lidar com maior complexidade nas integrações e principalmente lidar com os percalços de uma rede instável, com atrasos e falhas parciais.

É justamente essa instabilidade na rede que tira sistemas do ar e, cedo ou tarde, leva a falhas em cascata. Agora, o que era simples não é mais: uma troca de mensagem entre módulos deixou de ser uma chamada de método em memória para se tornar uma jornada lenta e cheia de problemas na rede. Entender a diferença entre escrever código com chamadas locais e remotas é essencial nesse mundo de processos, máquinas e regiões interconectados por protocolos, switches e roteadores na rede.

Por esse motivo, nessa talk, pretendo discutir como nós desenvolvedores podemos escrever sistemas e serviços mais resilientes e tolerantes a falhas, trazendo assim alguma estabilidade dentro desses ambientes distribuídos e instáveis por natureza.

(GRAVAÇÃO: https://youtu.be/TMmN9cR_IsM?list=PLHMMERsvy9EyWQPru4SrJAYHEGKfkjRgP&t=481)

Transcript

1. FAULT-TOLERANT CLIENTS Implementando clients e services mais resilientes e tolerantes a falhas
2. O que é um Sistema Tolerante a Falhas? 

3. https://deniseyu.io/art/
4. https://deniseyu.io/art/
5. https://deniseyu.io/art/
6. Desenhando sistemas distribuídos…
11. Spring Boot App
12. Spring Boot App
13. Spring Boot App Client Service
14. Spring Boot App Client Service
15. Spring Boot App Client Service Local Calls
16. Spring Boot App Client Service Local Calls
17. Spring Boot App Client Service Local Calls
18. Spring Boot App Client Service Local Calls Mas não aqui!
19. Spring Boot App Client Service Local Calls Mas não aqui!
20. Spring Boot App Client Service Local Calls
21. Em contrapartida…
22. Spring Boot App Spring Boot App
23. Spring Boot App Spring Boot App Client
24. Spring Boot App Spring Boot App Client Service
25. Spring Boot App Spring Boot App Client Service 
 Internet
26. Spring Boot App Spring Boot App Client Service 
 Internet
27. Spring Boot App Spring Boot App Client Service 
 Internet Remote Calls
28. Spring Boot App Spring Boot App Client Service 
 Internet Remote Calls
29. Spring Boot App Client Spring Boot App Service 
 Internet Remote Calls
30. Spring Boot App Client Spring Boot App Service 
 Internet Remote Calls
31. Spring Boot App Client Spring Boot App Service 
 Internet Remote Calls
32. Spring Boot App Client Spring Boot App Service 
 Internet Remote Calls
33. Spring Boot App Client Spring Boot App Service 
 Internet Remote Calls
34. Spring Boot App Spring Boot App 
 Internet Client Service Remote Calls
35. https://deniseyu.io/art/
36. https://deniseyu.io/art/
37. https://deniseyu.io/art/
38. https://deniseyu.io/art/
39. https://deniseyu.io/art/
41. Por que isso importa?
42. Spring Boot App Spring Boot App Spring Boot App 
 Local Calls Remote Calls
43. Spring Boot App Spring Boot App Spring Boot App 
 Centralized System Distributed System
44. Spring Boot App Spring Boot App Spring Boot App 
 Centralized System Distributed System
45. — Martin Fowler First Law of Distributed Object Design: 
 "don’t distribute your objects"
46. Mas se não tiver jeito…
47. Spring Boot App Client Spring Boot App Service 
 Internet Distributed System
48. Spring Boot App Client Spring Boot App Service 
 Internet Distributed System
50. Distributed System Spring Boot App Client Spring Boot App Service 
 Internet
51. Distributed System Spring Boot App Client Spring Boot App Service 
 Internet
52. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
53. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
54. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
55. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
56. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
57. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
58. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
59. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
60. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
61. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
62. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
63. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
64. Design for Failures
65. Rafael Ponte @rponte
67. Fortaleza - Terra do Sol
69. FAULT-TOLERANT CLIENTS Implementando clients e services mais resilientes e tolerantes a falhas
70. Implementação Ingênua
71. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
72. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
73. @RestController public class CalculadoraDeFretesController { @GetMapping(path="/fretes/calcula") public ResponseEntity<Frete> calcula(@RequestParam String cep) { // consulta frete em outro microsserviço String url = "https://ms.fast-fretes.com/calcula-frete/" ; 
 ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
 return ResponseEntity.ok(frete); } }
74. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
75. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
76. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
77. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute(); Pode ser qualquer HTTP Client!
78. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
79. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
80. ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
81. O problema dessa implementação…
82. Spring Boot App Client Spring Boot App Service 
 Internet
83. Spring Boot App Client Spring Boot App Service 
 Internet
84. Spring Boot App Client Spring Boot App Service 
 Internet
85. Spring Boot App Client Spring Boot App Service 
 Internet
86. Spring Boot App Client Spring Boot App Service 
 Internet
87. Spring Boot App Client Spring Boot App Service 
 Internet
88. Spring Boot App Client Spring Boot App Service 
 Internet
89. Spring Boot App Client Spring Boot App Service 
 Internet
90. Spring Boot App Client Spring Boot App Service 
 Internet
91. Spring Boot App Client Spring Boot App Service 
 Internet
92. Spring Boot App Client Spring Boot App Service 
 Internet
93. Spring Boot App Client Spring Boot App Service 
 Internet
94. Spring Boot App Client Spring Boot App Service 
 Internet
95. Spring Boot App Client Spring Boot App Service 
 Internet
96. Spring Boot App Client Spring Boot App Service 
 Internet
97. Spring Boot App Client Spring Boot App Service 
 Internet
98. Spring Boot App Client Spring Boot App Service 
 Internet
101. Tudo isso porque esperamos demais…
102. Timeout
103. ZupClientConfig config = // ... ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
104. ZupClientConfig config = // ... .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>() ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
105. ZupClientConfig config = // ... .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
106. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
107. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
108. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
109. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute(); Depende do caso de uso e contexto
110. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
111. Spring Boot App Client Spring Boot App Service 
 Internet
112. Spring Boot App Client Spring Boot App Service 
 Internet
113. Spring Boot App Client Spring Boot App Service 
 Internet
114. Spring Boot App Client Spring Boot App Service 
 Internet
115. Spring Boot App Client Spring Boot App Service 
 Internet
116. Fail Fast
117. …mas não para Transient Failures
118. Spring Boot App Client Spring Boot App Service 
 Internet
119. Spring Boot App Client Spring Boot App Service 
 Internet
120. Spring Boot App Client Spring Boot App Service 
 Internet
121. Spring Boot App Client Spring Boot App Service 
 Internet
122. Spring Boot App Client Spring Boot App Service 
 Internet
123. Spring Boot App Client Spring Boot App Service 
 Internet
124. Não podemos jogar esse problema no usuário…
125. Retry
126. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
127. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy( ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
128. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom().build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
129. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
130. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute(); Transient Failures
131. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .build() ) .build(); ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
132. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .build() ) .build(); ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute(); Depende do caso de uso e contexto
133. Spring Boot App Client Spring Boot App Service 
 Internet
134. Spring Boot App Client Spring Boot App Service 
 Internet
135. Spring Boot App Client Spring Boot App Service 
 Internet Original Request:
136. Spring Boot App Client Spring Boot App Service 
 Internet Original Request:
137. Spring Boot App Client Spring Boot App Service 
 Internet Retry #1: Original Request:
138. Spring Boot App Client Spring Boot App Service 
 Internet Retry #1: Retry #2: Original Request:
139. Spring Boot App Client Spring Boot App Service 
 Internet Retry #1: Retry #2: Original Request:
140. Clients são EGOISTAS
141. Spring Boot App Client Spring Boot App Service 
 Internet
142. Spring Boot App Client Spring Boot App Service 
 Internet
143. Spring Boot App Client Spring Boot App Service 
 Internet
144. Spring Boot App Client Spring Boot App Service 
 Internet
145. Spring Boot App Client Spring Boot App Service 
 Internet
146. Spring Boot App Client Spring Boot App Service 
 Internet
147. Spring Boot App Client Spring Boot App Service 
 Internet
148. Spring Boot App Client Spring Boot App Service 
 Internet
150. RETRY STORM 
 Vamo surrar esse servidor ae!
151. Não demos tempo pro serviço se recuperar
152. Retry with Backo f
153. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
154. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS) ) .build() ) .build(); ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
155. 100ms
 100ms
 100ms
 100ms
 …
 Retry #1 Retry #2 Retry #3 Retry #4
156. Não resolvemos o problema, somente "empurramos" ele 100ms pra frente…
157. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS) ) .build() ) .build(); ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
158. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS), 2 ) .build() ) .build(); ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
159. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS), 2 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute(); Delay Factor
160. 100ms
 200ms
 400ms
 800ms
 …
 Retry #1 Retry #2 Retry #3 Retry #4 Dobramos Dobramos Dobramos Dobramos
161. Retry with Exponential Backo f
162. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS), 2 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
163. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS), 2 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
164. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(Duration.of(100, MILLIS), 2 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
165. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(Duration.of(100, MILLIS) ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
166. Demos folêgo pro servidor ter tempo para se recuperar, porém…
168. SINCRONIA ENTRE CLIENTS
169. Precisamos diminuir as chances dessa sincronização…
170. Retry with Backo f f and Jitter
171. jitter /ˈdʒɪtə/ n. 
 the deviation from true periodicity of a presumably periodic signal.
172. jitter /ˈdʒɪtə/ n. 
 add randomness to the periodicity of a periodic signal.
173. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(Duration.of(100, MILLIS) ) .build() ) .build();
 ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
174. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(Duration.of(100, MILLIS) ) .withJitter(0.25 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute();
175. ZupClientConfig config = ZupClientConfig.custom( ) .withRequestTimeout(Duration.of(5, SECONDS) ) .withRetryPolicy(RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(Duration.of(100, MILLIS) ) .withJitter(0.25 ) .build() ) .build() ; ZupHttpClient<Frete> client = new ZupHttpClient<>(config) ; Frete frete = client.get(url ) .withParameter("cep", cep ) .execute(); Jitter Factor
176. delay random(0, delay*0.25) + -
177. delay random(0, delay*0.25) + -
178. delay random(0, delay*0.25) + -
179. delay random(0, delay*0.25) + -
180. delay random(0, delay*0.25) Jitter + -
181. 100ms
 200ms
 400ms
 800ms
 …
 Retry #1 Retry #2 Retry #3 Retry #4
182. 121ms +21ms 
 203ms +3ms 
 393ms -7ms 
 788ms -12ms 
 …
 Retry #1 Retry #2 Retry #3 Retry #4
183. Não só evitamos a sincronização…
184. … como também distribuímos melhor os requests entre os intervalos
185. Retry with Exponential Backo f https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/
186. Retry with Exponential Backo f https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/ Intervalos longos 
 e ociosos
187. Intervalos longos 
 e ociosos Retry with Exponential Backo f Picos ainda podem ocorrer https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/
188. Retry with Exponential Backo f f and Jitter https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/
189. Retry with Exponential Backo f f and Jitter https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/ Distribui as requisições entre os intervalos
190. Distribui as requisições entre os intervalos Retry with Exponential Backo f f and Jitter Menor incidência de picos https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/
191. Distribui as requisições entre os intervalos Retry with Exponential Backo f f and Jitter Menor incidência de picos https://aws.amazon.com/blogs/architecture/exponential-backo f f -and-jitter/
192. Pra entender melhor como tudo isso funciona…
193. Efeitos de Particionamento de Rede
194. RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(ofMillis(100)) .build( ) (Rede particionada) https://www.usenix.org/sites/default/ f i les/conference/protected- f i les/srecon18asia_slides_goh.pdf
195. RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(ofMillis(100)) .build( ) https://www.usenix.org/sites/default/ f i les/conference/protected- f i les/srecon18asia_slides_goh.pdf (Rede particionada)
196. RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(ofMillis(100)) .withJitter(0.25)
 .build() https://www.usenix.org/sites/default/ f i les/conference/protected- f i les/srecon18asia_slides_goh.pdf (Rede particionada)
197. Efeitos de falhas parciais
198. RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withDelay(ofMillis(100)) .build( ) (taxa de falha de 25 %) https://www.usenix.org/sites/default/ f i les/conference/protected- f i les/srecon18asia_slides_goh.pdf
199. RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(ofMillis(100)) .build( ) (taxa de falha de 25 %) https://www.usenix.org/sites/default/ f i les/conference/protected- f i les/srecon18asia_slides_goh.pdf
200. RetryPolicy.custom( ) .retryOn(HttpStatus5xxException.class ) .withMaxAttempts(3 ) .withExponentialBackoff(ofMillis(100)) .withJitter(0.25)
 .build() (taxa de falha de 25 %) https://www.usenix.org/sites/default/ f i les/conference/protected- f i les/srecon18asia_slides_goh.pdf
201. Concluindo…
202. Sistemas Distribuídos são complexos por natureza
203. Qualquer chamada remota é um potencial ponto de falha
204. Pontos de atenção
205. • Sempre de f i na Timeouts Pontos de atenção
206. • Sempre de f i na Timeouts • Não faça Retry (por default) Pontos de atenção
207. • Sempre de f i na Timeouts • Não faça Retry (por default) • Se f i zer Retry, faça Backo f f (exponential) Pontos de atenção
208. • Sempre de f i na Timeouts • Não faça Retry (por default) • Se f i zer Retry, faça Backo f f (exponential) • Sempre use Jitter Pontos de atenção
209. OBRIGADO!
210. @rponte Rafael Ponte