Exception with Blockhound in Spring Webflux using Thymeleaf - spring

Question

When enabling Blockhound for production in my Spring Boot application, whenever I try to process a request that returns a view from thymeleaf, blockhound throws an exception (probably due to a block when reading template files from disk):
Excepcion:
reactor.blockhound.BlockingOperationError: Blocking call! java.io.RandomAccessFile#readBytes
at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java) ~[na:na]
at java.base/java.io.RandomAccessFile.read(RandomAccessFile.java:406) ~[na:na]
at java.base/java.io.RandomAccessFile.readFully(RandomAccessFile.java:470) ~[na:na]
at java.base/java.util.zip.ZipFile$Source.readFullyAt(ZipFile.java:1304) ~[na:na]
at java.base/java.util.zip.ZipFile$ZipFileInputStream.initDataOffset(ZipFile.java:998) ~[na:na]
at java.base/java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:1013) ~[na:na]
at java.base/java.util.zip.ZipFile$ZipFileInflaterInputStream.fill(ZipFile.java:468) ~[na:na]
at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:159) ~[na:na]
at java.base/java.io.FilterInputStream.read(FilterInputStream.java:133) ~[na:na]
at java.base/java.io.FilterInputStream.read(FilterInputStream.java:107) ~[na:na]
at java.base/java.util.Properties$LineReader.readLine(Properties.java:499) ~[na:na]
at java.base/java.util.Properties.load0(Properties.java:415) ~[na:na]
at java.base/java.util.Properties.load(Properties.java:404) ~[na:na]
at org.springframework.web.util.HtmlCharacterEntityReferences.<init>(HtmlCharacterEntityReferences.java:75) ~[spring-web-5.3.3.jar:5.3.3]
at org.springframework.web.util.HtmlUtils.<clinit>(HtmlUtils.java:46) ~[spring-web-5.3.3.jar:5.3.3]
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.htmlEscape(AbstractErrorWebExceptionHandler.java:295) ~[spring-boot-autoconfigure-2.4.2.jar:2.4.2]
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.renderDefaultErrorView(AbstractErrorWebExceptionHandler.java:282) ~[spring-boot-autoconfigure-2.4.2.jar:2.4.2]
at org.springframework.boot.autoconfigure.web.reactive.error.DefaultErrorWebExceptionHandler.renderErrorView(DefaultErrorWebExceptionHandler.java:141) ~[spring-boot-autoconfigure-2.4.2.jar:2.4.2]
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.lambda$handle$0(AbstractErrorWebExceptionHandler.java:326) ~[spring-boot-autoconfigure-2.4.2.jar:2.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:125) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:73) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:82) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:177) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2359) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2167) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2041) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4046) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:208) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4046) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:106) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:392) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators.error(Operators.java:196) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoError.subscribe(MonoError.java:52) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4046) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:392) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError(MonoFlatMap.java:192) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onError(MonoFlatMap.java:259) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:106) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators.error(Operators.java:196) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:134) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap.subscribeOrReturn(MonoFlatMap.java:53) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4031) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:392) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError(MonoFlatMap.java:192) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onError(MonoFlatMap.java:259) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:129) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:127) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1789) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:128) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:366) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:218) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:164) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:157) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:73) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2359) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2167) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2041) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:157) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1789) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:249) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:210) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:210) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1789) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoIgnoreThen$ThenAcceptInner.onNext(MonoIgnoreThen.java:305) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1789) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:151) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1789) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoZip$ZipCoordinator.signal(MonoZip.java:251) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoZip$ZipInner.onNext(MonoZip.java:336) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:180) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2359) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.request(MonoPeekTerminal.java:139) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoZip$ZipInner.onSubscribe(MonoZip.java:325) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onSubscribe(MonoPeekTerminal.java:152) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4046) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoZip.subscribe(MonoZip.java:128) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:154) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:157) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:73) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:82) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:281) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:860) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:127) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:180) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2359) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.request(MonoPeekTerminal.java:139) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:169) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2167) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2041) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onSubscribe(MonoPeekTerminal.java:152) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4046) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:448) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:218) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:164) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.Mono.subscribe(Mono.java:4046) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:173) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.2.jar:3.4.2]
at reactor.netty.http.server.HttpServer$HttpServerHandle.onStateChange(HttpServer.java:860) ~[reactor-netty-http-1.0.3.jar:1.0.3]
at reactor.netty.ReactorNetty$CompositeConnectionObserver.onStateChange(ReactorNetty.java:638) ~[reactor-netty-core-1.0.3.jar:1.0.3]
at reactor.netty.transport.ServerTransport$ChildObserver.onStateChange(ServerTransport.java:475) ~[reactor-netty-core-1.0.3.jar:1.0.3]
at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:525) ~[reactor-netty-http-1.0.3.jar:1.0.3]
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94) ~[reactor-netty-core-1.0.3.jar:1.0.3]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:209) ~[reactor-netty-http-1.0.3.jar:1.0.3]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324) ~[netty-codec-4.1.58.Final.jar:4.1.58.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296) ~[netty-codec-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:719) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[netty-transport-4.1.58.Final.jar:4.1.58.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.58.Final.jar:4.1.58.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.58.Final.jar:4.1.58.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.58.Final.jar:4.1.58.Final]
at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]
Application.java
#SpringBootApplication
public class Application implements CommandLineRunner {
public static void main(String[] args) {
BlockHound.install();
SpringApplication.run(Application.class, args);
}
}
pom.xml dependencies
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>2020.0.1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.4.2</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>io.springfox</groupId>
<artifactId>springfox-boot-starter</artifactId>
<version>3.0.0</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!--
<dependency>
<groupId>org.thymeleaf</groupId>
<artifactId>thymeleaf-spring5</artifactId>
</dependency>
-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-validation</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
</dependency>
<!-- https://mvnrepository.com/artifact/io.projectreactor.tools/blockhound -->
<dependency>
<groupId>io.projectreactor.tools</groupId>
<artifactId>blockhound</artifactId>
<version>1.0.6.RELEASE</version>
</dependency>
<!-- Test -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
</dependencies>
I have also tried another configuration: removing spring boot thymeleaf auto configuration and declaring webflux reactive thymeleaf view resolver by myself, but if did not work either:
Changes in pom.xml:
<!--
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
-->
<dependency>
<groupId>org.thymeleaf</groupId>
<artifactId>thymeleaf-spring5</artifactId>
</dependency>
ViewConfiguration.java
#Setter
#Configuration
public class ViewConfiguration implements ApplicationContextAware, WebFluxConfigurer {
ApplicationContext applicationContext;
#Bean
public ITemplateResolver thymeleafTemplateResolver() {
final SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
resolver.setApplicationContext(this.applicationContext);
resolver.setPrefix("classpath:templates/");
resolver.setSuffix(".html");
resolver.setTemplateMode(TemplateMode.HTML);
resolver.setCacheable(false);
resolver.setCheckExistence(false);
return resolver;
}
#Bean
public ISpringWebFluxTemplateEngine thymeleafTemplateEngine() {
SpringWebFluxTemplateEngine templateEngine = new SpringWebFluxTemplateEngine();
templateEngine.setTemplateResolver(thymeleafTemplateResolver());
return templateEngine;
}
#Bean
public ThymeleafReactiveViewResolver thymeleafReactiveViewResolver() {
ThymeleafReactiveViewResolver viewResolver = new ThymeleafReactiveViewResolver();
viewResolver.setTemplateEngine(thymeleafTemplateEngine());
return viewResolver;
}
#Override
public void configureViewResolvers(ViewResolverRegistry registry) {
registry.viewResolver(thymeleafReactiveViewResolver());
}
}
I supposed the problem is related with thymeleaf because when the request does not involve any thymeleaf template (standard REST API call) if works perfectly.
What am I missing here?

Answer 1

Thymeleaf seems to use the legacy, blocking way of loading it's template files.
Replace
BlackHound.install()
with
BlockHound.builder()
.allowBlockingCallsInside("org.thymeleaf.util.ClassLoaderUtils", "loadResourceAsStream")
.install()
Works for me at least.