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The Value of Reactive Design - Stéphane Maldini

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VMware Tanzu

Reactive programming offers significant benefits over traditional blocking programming models including: - Much higher efficiency through lower resource usage (e.g. threads), allowing applications to handle higher throughput with fewer servers. - Better scalability to handle high connection volumes and latency variability since reactive applications are not blocked and can continue processing other requests. - Increased resilience through failure isolation and built-in support for asynchronous, non-blocking operations with backpressure.

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The Value Of Reactive Stephane Maldini - Reactive Engineering @ Pivotal @smaldini
The Value Of Reactive What is it ? Where is the value ?
3 No, I do not have a medium blog =+
Reactive Programming ● The next frontier for high-efficiency applications ● Non-blocking and allows for concurrent executions ● Often associated with functional programming ● Have no opinion on async and many flows are totally synchronous ● Resilient with graceful error handling and interruptions (producer or consumer related)
Reactive Programming ● The next frontier for high-efficiency applications ● Non-blocking and allows for concurrent executions ● Often associated with functional programming ● Have no opinion on async and many flows are totally synchronous ● Resilient with graceful error handling and interruptions (producer or consumer related) 😴
A reactive API primer 5 @GetMapping("/health") public Mono<Health> compositeHealth() { return Mono.zip( webClient.get() .uri(“https://alpha-service/health") .retrieve() .bodyToMono(Health.class), webClient.get() .uri("https://bravo-service/health") .retrieve() .bodyToMono(Health.class), (alpha, bravo) -> composite(alpha, bravo)) .switchIfEmpty(emptyComposite()); }
But, is it only a writing style issue ? 6
Debugging Reactive flows 7 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] …
Debugging Reactive flows 7 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] …
Debugging Reactive flows 7 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] … You ?
Using blocking code in reactive callbacks 8 TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody();
Using blocking code in reactive callbacks 9 someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; });
Using blocking code in reactive callbacks 9 someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); 💩
10 You
What are you priorities ? 11
What are you priorities ? 12 Time To Market / Dev Productivity
What are you priorities ? 13 Time To Market / Dev Productivity Day 2 Operations / Observability
What are you priorities ? 14 Time To Market / Dev Productivity Day 2 Operations / Observability […]
What are you priorities ? 15 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
What are you priorities ? 16 Time To Market / Dev Productivity Day 2 Operations / Observability Reactive ?Running costs / efficiency […]
Give me 17 Reasons To use this stuff
18 Order(s) of Magnitude 
 more efficient 🤑
• Lower Number of processes/threads used by instance • Lower Memory Pressure and associated costs (Garbage collectors) • Lower Hardware specification requirements • Lower Startup time 19 Order(s) of Magnitude 
 more efficient
Show me some numbers 20 Order(s) of Magnitude 
 more efficient
21 Order(s) of Magnitude 
 more efficient Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a simple hello world String rendering 128 / steps up to 4000 20s 20min
22 Order(s) of Magnitude 
 more efficient
23 Order(s) of Magnitude 
 more efficient MVCWebFlux
24 Order(s) of Magnitude 
 more efficient 😎 🤒
25 Order(s) of Magnitude 
 more efficient Moar Old Gen Moar Young Gen
26 Order(s) of Magnitude 
 more efficient
27 Order(s) of Magnitude 
 more efficient x2
28 Order(s) of Magnitude 
 more efficient 😎 ⏰
29 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
• Lower Number of instances running a same application • Lower Impact from traffic latency diversity • Lower Impact from persistent http traffic (websocket, sse, http2…) 30 Designed for 
 connection volume scalability
31 Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a 100ms delayed hello world String rendering 128 / steps up to 4000 20s 20min Designed for 
 connection volume scalability
Designed for 
 connection volume scalability 32 MVC (async)WebFlux
Designed for 
 connection volume scalability 33🤢
34 Designed for 
 connection volume scalability
35 x4 Designed for 
 connection volume scalability
36 ⏰⏰ Designed for 
 connection volume scalability
How does the response delay impact each model ? 37 Designed for 
 connection volume scalability
38 Designed for 
 connection volume scalability WebFlux WebFlux (with response delay)
WebFlux WebFlux (with response delay) 39 Designed for 
 connection volume scalability
WebFlux WebFlux (with response delay) 40 Designed for 
 connection volume scalability No major impact from backend delays
41 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC
42 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC Rapidly degrading running conditions
43 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay)
44 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay) x4 slower due to backend delays
45 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
46 Sleep Well,
 get less paged 📟 Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
Sleep Well,
 get less paged • Greater resilience to runtime errors, including memory issues • Greater availability at any point in time, specially under stress • Easier resources use modeling 47
Sleep Well,
 get less paged 48 Figure 1.a: 
 A blocking JVM HTTP server with no flow control
Sleep Well,
 get less paged 48 Figure 1.a: 
 A blocking JVM HTTP server with no flow control
Sleep Well,
 get less paged Reactive IO allows reading when application capacity permits 49
Sleep Well,
 get less paged Reactive IO only requests application data to write when client capacity permits 50
51 WebFlux WebFlux (with response delay) Sleep Well,
 get less paged
52 WebFlux WebFlux (with response delay) Very similar resources use profile Sleep Well,
 get less paged
Sleep Well,
 get less paged 53 Can reactive programming help with JVM OutOfMemory exceptions caused by incoming request traffic ?
Sleep Well,
 get less paged • Yes, using a reactive IO runtime, request body overflow is isolated • Errors are propagated via the reactive flow error route : onError • Associated connection will usually be closed or a fallback route will be provided • With a blocking runtime, errors are bubbling up and OutOfMemory will be fatal • Long JVM pauses will lead to a full app crash or unrecoverable state 54
55 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
56 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability Event-Driven Less Threads - Memory Start quicker Improve Latency* Unlocks hyper concurrency Connected Experience Slow/Fast traffic Near-Always Available Flow Control Predictable load Resilient
57 What do you do with these qualities ? 🤓
58 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
59 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
60 Remote calls parallelization With Spring, you can start writing your app with WebMVC, introduce WebClient to improve backend calls workflows, then consider moving to WebFlux Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
61 Write an Edge API Available Traffic Control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
62 Write an Edge API Available Traffic Control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
63 Traffic Control A reactive runtime will isolate ingress/egress traffic latency and exceptions. Given this isolation property, a reactive Edge API should always be able to route traffic, even limit it or short-circuit when required. Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
64 Mobile Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
65 Mobile IoT Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
Ok sounds cool, but what about the developer experience ? 66 😷
67 Error has been observed at the following site(s): |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.csrf.CsrfWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.web.reactive.filter.OrderedHiddenHttpMethodFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ HTTP GET "/quotes/summary/MSFT" [ExceptionHandlingWebHandler] Exceptions since Spring Framework 5.2
67 Error has been observed at the following site(s): |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.csrf.CsrfWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.web.reactive.filter.OrderedHiddenHttpMethodFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ HTTP GET "/quotes/summary/MSFT" [ExceptionHandlingWebHandler] Exceptions since Spring Framework 5.2 Actionable stacktraces
68 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled
69 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled
69 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled Reactive Developer productivity
70 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
71 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients Speaking of which…
72 BlockHound ! Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients https://github.com/reactor/BlockHound
Detecting blocking code in reactive stack 73 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; });
Detecting blocking code in reactive stack 74 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); java.lang.Error: Blocking call! java.net.Socket#connect at reactor.blockhound.BlockHound$Builder.lambda$new$0(BlockHound.java:154) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHound$Builder.lambda$install$8(BlockHound.java:254) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHoundRuntime.checkBlocking(BlockHoundRuntime.java:43) ~[blockhound-1.0.0.jar:na] at java.net.Socket.connect(Socket.java) ~[na:1.8.0_144] at sun.net.NetworkClient.doConnect(NetworkClient.java:180) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:339) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:357) ~[na:1.8.0_144]
Detecting blocking code in reactive stack 74 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); java.lang.Error: Blocking call! java.net.Socket#connect at reactor.blockhound.BlockHound$Builder.lambda$new$0(BlockHound.java:154) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHound$Builder.lambda$install$8(BlockHound.java:254) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHoundRuntime.checkBlocking(BlockHoundRuntime.java:43) ~[blockhound-1.0.0.jar:na] at java.net.Socket.connect(Socket.java) ~[na:1.8.0_144] at sun.net.NetworkClient.doConnect(NetworkClient.java:180) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:339) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:357) ~[na:1.8.0_144] Quickly detect during pre-production workflows that will likely degrade your reactive stack experience
More reactive microservices ? 75
80% of apps generated by start.spring.io are using a SQL driver 76
80% of apps generated by start.spring.io are using a SQL driver 77 r2dbc.io
What should I look after I successfully have written my first Reactive apps ? 78
Monitoring with Micrometer 79 micrometer.io
80 Networking with RSocket rsocket.io
81 Having fun developing with Kotlin kotlinlang.org
So In Conclusion 82
What are you priorities ? 83 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
What are you priorities ? 83 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You can actually be more productive in writing state of the art, scalable microservices
What are you priorities ? 84 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
What are you priorities ? 84 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive Your Applications are designed to be resilient under stress and naturally lower maintenance
What are you priorities ? 85 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
What are you priorities ? 85 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You run more for less
What are you priorities ? 86 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
87 Establish the right project to experiment Reactive Programming with
88 Do it progressively, migrate a few dedicated backend routes then an entire application You can already parallelize some workloads even on your blocking stack
89 Qualify a few benefits identified in this session Establish your own benchmark to verify the outcome !
90 Use all the developers tools you can to accelerate your reactive adoption and build trust
91 Once the learning curve price has been paid and the benefits realized- it’s usually difficult to come back to blocking solutions.
92 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack.
93 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack. It’s just designed for them
THANK YOU @smaldini smaldini

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The Value of Reactive Design - Stéphane Maldini

  • 1. The Value Of Reactive Stephane Maldini - Reactive Engineering @ Pivotal @smaldini
  • 2. The Value Of Reactive What is it ? Where is the value ?
  • 3. 3 No, I do not have a medium blog =+
  • 4. Reactive Programming ● The next frontier for high-efficiency applications ● Non-blocking and allows for concurrent executions ● Often associated with functional programming ● Have no opinion on async and many flows are totally synchronous ● Resilient with graceful error handling and interruptions (producer or consumer related)
  • 5. Reactive Programming ● The next frontier for high-efficiency applications ● Non-blocking and allows for concurrent executions ● Often associated with functional programming ● Have no opinion on async and many flows are totally synchronous ● Resilient with graceful error handling and interruptions (producer or consumer related) 😴
  • 6. A reactive API primer 5 @GetMapping("/health") public Mono<Health> compositeHealth() { return Mono.zip( webClient.get() .uri(“https://alpha-service/health") .retrieve() .bodyToMono(Health.class), webClient.get() .uri("https://bravo-service/health") .retrieve() .bodyToMono(Health.class), (alpha, bravo) -> composite(alpha, bravo)) .switchIfEmpty(emptyComposite()); }
  • 7. But, is it only a writing style issue ? 6
  • 8. Debugging Reactive flows 7 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] …
  • 9. Debugging Reactive flows 7 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] …
  • 10. Debugging Reactive flows 7 java.lang.RuntimeException: Am I looking like a nice stacktrace friends ? at io.spring.workshop.tradingservice.TradingCompanyClient.lambda$getTradingCompany$0(TradingCompanyClient.java:38) ~[classes/:na] at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:190) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onNext(FluxOnAssembly.java:349) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxContextStart$ContextStartSubscriber.onNext(FluxContextStart.java:103) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:331) ~[reactor-core-3.3.0] at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1575) ~[reactor-core-3.3.0] at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:121) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:252) ~[reactor-core-3.3.0] at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.0] at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:197) ~[reactor-netty-0.9.0] at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:338) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:350) ~[reactor-netty-0.9.0] at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:399) ~[reactor-netty-0.9.0] at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:555) ~[reactor-netty-0.9.0] … You ?
  • 11. Using blocking code in reactive callbacks 8 TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody();
  • 12. Using blocking code in reactive callbacks 9 someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; });
  • 13. Using blocking code in reactive callbacks 9 someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); 💩
  • 15. What are you priorities ? 11
  • 16. What are you priorities ? 12 Time To Market / Dev Productivity
  • 17. What are you priorities ? 13 Time To Market / Dev Productivity Day 2 Operations / Observability
  • 18. What are you priorities ? 14 Time To Market / Dev Productivity Day 2 Operations / Observability […]
  • 19. What are you priorities ? 15 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 20. What are you priorities ? 16 Time To Market / Dev Productivity Day 2 Operations / Observability Reactive ?Running costs / efficiency […]
  • 22. 18 Order(s) of Magnitude 
 more efficient 🤑
  • 23. • Lower Number of processes/threads used by instance • Lower Memory Pressure and associated costs (Garbage collectors) • Lower Hardware specification requirements • Lower Startup time 19 Order(s) of Magnitude 
 more efficient
  • 24. Show me some numbers 20 Order(s) of Magnitude 
 more efficient
  • 25. 21 Order(s) of Magnitude 
 more efficient Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a simple hello world String rendering 128 / steps up to 4000 20s 20min
  • 26. 22 Order(s) of Magnitude 
 more efficient
  • 27. 23 Order(s) of Magnitude 
 more efficient MVCWebFlux
  • 28. 24 Order(s) of Magnitude 
 more efficient 😎 🤒
  • 29. 25 Order(s) of Magnitude 
 more efficient Moar Old Gen Moar Young Gen
  • 30. 26 Order(s) of Magnitude 
 more efficient
  • 31. 27 Order(s) of Magnitude 
 more efficient x2
  • 32. 28 Order(s) of Magnitude 
 more efficient 😎 ⏰
  • 33. 29 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
  • 34. • Lower Number of instances running a same application • Lower Impact from traffic latency diversity • Lower Impact from persistent http traffic (websocket, sse, http2…) 30 Designed for 
 connection volume scalability
  • 35. 31 Spring WebFlux.Fn - Reactor Netty - 4 threads & Spring MVC - Tomcat - 200 threads With a 100ms delayed hello world String rendering 128 / steps up to 4000 20s 20min Designed for 
 connection volume scalability
  • 36. Designed for 
 connection volume scalability 32 MVC (async)WebFlux
  • 37. Designed for 
 connection volume scalability 33🤢
  • 38. 34 Designed for 
 connection volume scalability
  • 39. 35 x4 Designed for 
 connection volume scalability
  • 41. How does the response delay impact each model ? 37 Designed for 
 connection volume scalability
  • 42. 38 Designed for 
 connection volume scalability WebFlux WebFlux (with response delay)
  • 43. WebFlux WebFlux (with response delay) 39 Designed for 
 connection volume scalability
  • 44. WebFlux WebFlux (with response delay) 40 Designed for 
 connection volume scalability No major impact from backend delays
  • 45. 41 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC
  • 46. 42 Designed for 
 connection volume scalability WebMVC (with response delay)WebMVC Rapidly degrading running conditions
  • 47. 43 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay)
  • 48. 44 Designed for 
 connection volume scalability WebMVC WebMVC (with response delay) x4 slower due to backend delays
  • 49. 45 Designed for 
 connection volume scalability 📱Order(s) of Magnitude 
 more efficient
  • 50. 46 Sleep Well,
 get less paged 📟 Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
  • 51. Sleep Well,
 get less paged • Greater resilience to runtime errors, including memory issues • Greater availability at any point in time, specially under stress • Easier resources use modeling 47
  • 52. Sleep Well,
 get less paged 48 Figure 1.a: 
 A blocking JVM HTTP server with no flow control
  • 53. Sleep Well,
 get less paged 48 Figure 1.a: 
 A blocking JVM HTTP server with no flow control
  • 54. Sleep Well,
 get less paged Reactive IO allows reading when application capacity permits 49
  • 55. Sleep Well,
 get less paged Reactive IO only requests application data to write when client capacity permits 50
  • 56. 51 WebFlux WebFlux (with response delay) Sleep Well,
 get less paged
  • 57. 52 WebFlux WebFlux (with response delay) Very similar resources use profile Sleep Well,
 get less paged
  • 58. Sleep Well,
 get less paged 53 Can reactive programming help with JVM OutOfMemory exceptions caused by incoming request traffic ?
  • 59. Sleep Well,
 get less paged • Yes, using a reactive IO runtime, request body overflow is isolated • Errors are propagated via the reactive flow error route : onError • Associated connection will usually be closed or a fallback route will be provided • With a blocking runtime, errors are bubbling up and OutOfMemory will be fatal • Long JVM pauses will lead to a full app crash or unrecoverable state 54
  • 60. 55 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability
  • 61. 56 Sleep Well,
 get less paged Order(s) of Magnitude 
 more efficient Designed for 
 connection volume scalability Event-Driven Less Threads - Memory Start quicker Improve Latency* Unlocks hyper concurrency Connected Experience Slow/Fast traffic Near-Always Available Flow Control Predictable load Resilient
  • 62. 57 What do you do with these qualities ? 🤓
  • 63. 58 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 64. 59 Write Any Microservice Resilient Smaller resources footprint Remote calls parallelization Hedge Clients Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 65. 60 Remote calls parallelization With Spring, you can start writing your app with WebMVC, introduce WebClient to improve backend calls workflows, then consider moving to WebFlux Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 66. 61 Write an Edge API Available Traffic Control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 67. 62 Write an Edge API Available Traffic Control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 68. 63 Traffic Control A reactive runtime will isolate ingress/egress traffic latency and exceptions. Given this isolation property, a reactive Edge API should always be able to route traffic, even limit it or short-circuit when required. Edge API Available Traffic control Volume of Connections Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 69. 64 Mobile Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
  • 70. 65 Mobile IoT Backend Scale with different traffic latency Connected experience (notifications…) Volume of clients
  • 71. Ok sounds cool, but what about the developer experience ? 66 😷
  • 72. 67 Error has been observed at the following site(s): |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.csrf.CsrfWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.web.reactive.filter.OrderedHiddenHttpMethodFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ HTTP GET "/quotes/summary/MSFT" [ExceptionHandlingWebHandler] Exceptions since Spring Framework 5.2
  • 73. 67 Error has been observed at the following site(s): |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LogoutPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.ui.LoginPageGeneratingWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.csrf.CsrfWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.web.reactive.filter.OrderedHiddenHttpMethodFilter [DefaultWebFilterChain] |_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain] |_ checkpoint ⇢ HTTP GET "/quotes/summary/MSFT" [ExceptionHandlingWebHandler] Exceptions since Spring Framework 5.2 Actionable stacktraces
  • 74. 68 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled
  • 75. 69 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled
  • 76. 69 Error has been observed at the following site(s): |_ Mono.doOnNext ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:38) |_ Mono.switchIfEmpty ⇢ at io.spring.workshop.tradingservice.TradingCompanyClient.getTradingCompany(TradingCompanyClient.java:39) |_ Mono.zipWith ⇢ at io.spring.workshop.tradingservice.QuotesController.quotesDetails(QuotesController.java:39) |_ Mono.switchIfEmpty ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:119) |_ Mono.flatMap ⇢ at org.springframework.http.codec.EncoderHttpMessageWriter.write(EncoderHttpMessageWriter.java:123) |_ checkpoint ⇢ Handler io.spring.workshop.tradingservice.QuotesController#quotesDetails(String) [DispatcherHandler] |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.lambda$handleResult$5(DispatcherHandler.java:172) |_ Mono.onErrorResume ⇢ at org.springframework.web.reactive.DispatcherHandler.handleResult(DispatcherHandler.java:171) |_ Mono.flatMap ⇢ at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:147) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ Mono.switchIfEmpty ⇢ at org.springframework.security.web.server.authorization.AuthorizationWebFilter.filter(AuthorizationWebFilter.java:46) |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain] |_ Mono.defer ⇢ at org.springframework.web.server.handler.DefaultWebFilterChain.filter(DefaultWebFilterChain.java:119) |_ FluxMap$MapSubscriber.onComplete ⇢ at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:391) Exceptions with debug mode enabled Reactive Developer productivity
  • 77. 70 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients
  • 78. 71 Soon coming as a jvm agent Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients Speaking of which…
  • 79. 72 BlockHound ! Mobile Backend Scale even with different traffic latency Connected experience (notifications…) Volume of clients https://github.com/reactor/BlockHound
  • 80. Detecting blocking code in reactive stack 73 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; });
  • 81. Detecting blocking code in reactive stack 74 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); java.lang.Error: Blocking call! java.net.Socket#connect at reactor.blockhound.BlockHound$Builder.lambda$new$0(BlockHound.java:154) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHound$Builder.lambda$install$8(BlockHound.java:254) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHoundRuntime.checkBlocking(BlockHoundRuntime.java:43) ~[blockhound-1.0.0.jar:na] at java.net.Socket.connect(Socket.java) ~[na:1.8.0_144] at sun.net.NetworkClient.doConnect(NetworkClient.java:180) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:339) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:357) ~[na:1.8.0_144]
  • 82. Detecting blocking code in reactive stack 74 BlockHound.install(); someMono.doOnSuccess(data -> { TradingCompany tradingCompany = this.restTemplate.exchange( get("http://localhost:8082/details/{ticker}", ticker), TradingCompany.class) .getBody(); return tradingCompany; }); java.lang.Error: Blocking call! java.net.Socket#connect at reactor.blockhound.BlockHound$Builder.lambda$new$0(BlockHound.java:154) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHound$Builder.lambda$install$8(BlockHound.java:254) ~[blockhound-1.0.0.jar:na] at reactor.blockhound.BlockHoundRuntime.checkBlocking(BlockHoundRuntime.java:43) ~[blockhound-1.0.0.jar:na] at java.net.Socket.connect(Socket.java) ~[na:1.8.0_144] at sun.net.NetworkClient.doConnect(NetworkClient.java:180) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:339) ~[na:1.8.0_144] at sun.net.www.http.HttpClient.New(HttpClient.java:357) ~[na:1.8.0_144] Quickly detect during pre-production workflows that will likely degrade your reactive stack experience
  • 84. 80% of apps generated by start.spring.io are using a SQL driver 76
  • 85. 80% of apps generated by start.spring.io are using a SQL driver 77 r2dbc.io
  • 86. What should I look after I successfully have written my first Reactive apps ? 78
  • 89. 81 Having fun developing with Kotlin kotlinlang.org
  • 91. What are you priorities ? 83 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 92. What are you priorities ? 83 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You can actually be more productive in writing state of the art, scalable microservices
  • 93. What are you priorities ? 84 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 94. What are you priorities ? 84 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive Your Applications are designed to be resilient under stress and naturally lower maintenance
  • 95. What are you priorities ? 85 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 96. What are you priorities ? 85 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […] With Reactive You run more for less
  • 97. What are you priorities ? 86 Time To Market / Dev Productivity Day 2 Operations / Observability Running costs / efficiency […]
  • 98. 87 Establish the right project to experiment Reactive Programming with
  • 99. 88 Do it progressively, migrate a few dedicated backend routes then an entire application You can already parallelize some workloads even on your blocking stack
  • 100. 89 Qualify a few benefits identified in this session Establish your own benchmark to verify the outcome !
  • 101. 90 Use all the developers tools you can to accelerate your reactive adoption and build trust
  • 102. 91 Once the learning curve price has been paid and the benefits realized- it’s usually difficult to come back to blocking solutions.
  • 103. 92 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack.
  • 104. 93 In fact it’s difficult in today’s world of distributed systems to not find a reason for giving a go to any Reactive stack. It’s just designed for them