RSocket and Spring not handle multiple requests - spring

Question

I play with RSocket together with Spring boot. I want to make simple request-response example. As example I took code from this link:
https://www.baeldung.com/spring-boot-rsocket#request-response
Source code:
https://github.com/eugenp/tutorials/tree/master/spring-5-webflux/src/main/java/com/baeldung/spring/rsocket
When I run example code without change I get error during request with Exception. This error is not point of this question, but I just want to show changes comapre to original source by baeldung.
[reactor-tcp-nio-1]
org.springframework.core.log.CompositeLog: [5927a44d-9] 500 Server
Error for HTTP GET "/current/pko"
io.rsocket.exceptions.ApplicationErrorException: No handler for
destination '' at
io.rsocket.exceptions.Exceptions.from(Exceptions.java:76) Suppressed:
reactor.core.publisher.FluxOnAssembly$OnAssemblyException: Error has
been observed at the following site(s): |_ checkpoint ⇢ Handler
com.baeldung.spring.rsocket.client.MarketDataRestController#current(String)
[DispatcherHandler] |_ checkpoint ⇢ HTTP GET "/current/pko"
[ExceptionHandlingWebHandler] Stack trace: at
io.rsocket.exceptions.Exceptions.from(Exceptions.java:76) at
io.rsocket.core.RSocketRequester.handleFrame(RSocketRequester.java:706)
at
io.rsocket.core.RSocketRequester.handleIncomingFrames(RSocketRequester.java:640)
at
reactor.core.publisher.LambdaSubscriber.onNext(LambdaSubscriber.java:160)
at
reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onNext(MonoFlatMapMany.java:242)
at
reactor.core.publisher.FluxGroupBy$UnicastGroupedFlux.drainRegular(FluxGroupBy.java:554)
at
reactor.core.publisher.FluxGroupBy$UnicastGroupedFlux.drain(FluxGroupBy.java:630)
at
reactor.core.publisher.FluxGroupBy$UnicastGroupedFlux.onNext(FluxGroupBy.java:670)
at
reactor.core.publisher.FluxGroupBy$GroupByMain.onNext(FluxGroupBy.java:205)
at
reactor.core.publisher.FluxHandle$HandleSubscriber.onNext(FluxHandle.java:112)
at
reactor.core.publisher.FluxMap$MapConditionalSubscriber.onNext(FluxMap.java:213)
at
reactor.core.publisher.FluxMap$MapConditionalSubscriber.onNext(FluxMap.java:213)
at
reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:260)
at
reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:366)
at
reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:358)
at
reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:96)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at
io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)
at
io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at
io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at
io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at
io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at
io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714)
at
io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650)
at
io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) at
io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)
So I change client code from
#Configuration
public class ClientConfiguration {
#Bean
public RSocket rSocket() {
return RSocketFactory.connect()
.mimeType(MimeTypeUtils.APPLICATION_JSON_VALUE, MimeTypeUtils.APPLICATION_JSON_VALUE)
.frameDecoder(PayloadDecoder.ZERO_COPY)
.transport(TcpClientTransport.create(7000))
.start()
.block();
}
#Bean
RSocketRequester rSocketRequester(RSocketStrategies rSocketStrategies) {
return RSocketRequester.wrap(rSocket(), MimeTypeUtils.APPLICATION_JSON, MimeTypeUtils.APPLICATION_JSON, rSocketStrategies);
}
}
to
#Configuration
public class ClientConfiguration {
#Bean
RSocketRequester rSocketRequester(RSocketStrategies rSocketStrategies) {
return RSocketRequester.builder()
.rsocketStrategies(rSocketStrategies)
.connectTcp("localhost", 7000)
.block();
}
}
This small change help, an exception does not occur. Other issue that is point of that question iis that requests from client(requester) are processed one by one by server(responder). I create SOAPUI REST project and run GET request in 2 thread. It look like server use single thread. This is not what I expect to achieve.
To make it easy I will show whole solution.
Server :
Simple controller
#Controller
public class MarketDataRSocketController {
Logger logger = LoggerFactory.getLogger(MarketDataRSocketController.class);
private final MarketDataRepository marketDataRepository;
public MarketDataRSocketController(MarketDataRepository marketDataRepository) {
this.marketDataRepository = marketDataRepository;
}
#MessageMapping("currentMarketData")
public Mono<MarketData> currentMarketData(MarketDataRequest marketDataRequest) {
logger.info("Getting data for: "+marketDataRequest);
Mono<MarketData> result = marketDataRepository.getOne(marketDataRequest.getStock());
logger.info("Controller thread move forward: "+marketDataRequest);
return result;
}
#MessageExceptionHandler
public Mono<MarketData> handleException(Exception e) {
return Mono.just(MarketData.fromException(e));
}
}
In repository I add Thread.sleep(10000); just to simulate long running operation.
#Component
public class MarketDataRepository {
Logger logger = LoggerFactory.getLogger(MarketDataRSocketController.class);
private static final int BOUND = 100;
private Random random = new Random();
public Mono<MarketData> getOne(String stock) {
//return return Mono.just(getMarketDataResponse(stock)); original code from baeldung.
return Mono.just(stock).map(s -> getMarketDataResponse(s));
}
private MarketData getMarketDataResponse(String stock) {
logger.info("Repository thread go speel ZzzZZ");
try {
Thread.sleep(10000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
logger.info("Repository thread move forward");
return new MarketData(stock, random.nextInt(BOUND));
}
}
Client
Simple client configuration:
#Configuration
public class ClientConfiguration {
#Bean
RSocketRequester rSocketRequester(RSocketStrategies rSocketStrategies) {
return RSocketRequester.builder()
.rsocketStrategies(rSocketStrategies)
.connectTcp("localhost", 7000)
.block();
}
}
And simple REST Controller that I use in SOAP UI
#RestController
public class MarketDataRestController {
Logger logger = LoggerFactory.getLogger(MarketDataRestController.class);
private final Random random = new Random();
private final RSocketRequester rSocketRequester;
public MarketDataRestController(RSocketRequester rSocketRequester) {
this.rSocketRequester = rSocketRequester;
}
#GetMapping(value = "/current/{stock}")
public Publisher<MarketData> current(#PathVariable("stock") String stock) {
logger.info("Get REST call for stock : "+stock);
return rSocketRequester.route("currentMarketData")
.data(new MarketDataRequest(stock))
.retrieveMono(MarketData.class);
}
}
When i RUN server and client I get incomprehensible behavior to me. By SOAP UI I make single request in 2 threads.
In client log I get:
2021-09-01 11:30:14,614 INFO [reactor-http-nio-2] com.baeldung.spring.rsocket.client.MarketDataRestController: Get REST call for stock : pko
2021-09-01 11:30:14,691 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.client.MarketDataRestController: Get REST call for stock : pko
In server I get logs like:
Log from first shot:
// get data from client
2021-09-01 11:30:14,843 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRSocketController: Getting data for: MarketDataRequest(stock=pko)
// Log that Contoller thread go forward after call repository
2021-09-01 11:30:14,844 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRSocketController: Controller thread move forward: MarketDataRequest(stock=pko)
// Log that repository sleep thread
2021-09-01 11:30:14,862 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRepository: Repository thread go speel ZzzZZ
// Repository finish work
2021-09-01 11:30:24,863 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRepository: Repository thread move forward
Server is procesing only single call and just wait when repository finish job. Then process next request in similar way:
2021-09-01 11:30:24,874 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRSocketController: Getting data for: MarketDataRequest(stock=pko)
2021-09-01 11:30:24,874 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRSocketController: Controller thread move forward: MarketDataRequest(stock=pko)
2021-09-01 11:30:24,874 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRepository: Repository thread go speel ZzzZZ
2021-09-01 11:30:34,876 INFO [reactor-http-nio-3] com.baeldung.spring.rsocket.server.MarketDataRepository: Repository thread move forward
I don't understand why the server is processing calls one by one. Maybe there is some problem in code or maybe I'm not understand something right.
Thank you in advance.

Answer 1

In Reactor, by default, everything is running on the main thread. Calling Thread.sleep the main thread is blocking and the application freezes. if you would like to simulate a long-running operation you could use the delayElements operator:
.delayElements(Duration.ofSeconds(10));
Note: Reactor BlockHound detects and reports such blocking calls.