Unable to whitelist java.io.RandomAccessFile#readBytes

Question

Unable to whitelist java.io.RandomAccessFile#readBytes

jaschenk opened this issue 4 years ago · 2 comments

Have all other tests passing with the exception of this one, which uses a WebTestClient.bindToServer()... usage.
All other tests using WebTestClient.bindToServer()... work correctly.

However, this test, the third test in a test flow, performs the validation of a JWT. But always fails due to:
eactor.blockhound.BlockingOperationError: Blocking call! java.io.RandomAccessFile#readBytes
at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java) and returns a 400 bad request.

I have tested the same endpoint with the server locally running and it works correctly, not in a test scenario.

Expected Behavior

I believe I should be able to add a 'allowBlockingCallsInside' to the integration class and this exception would not be generated.

As in the following:
/**

BlockHoundIntegration
Please see: https://medium.com/@domenicosibilio/blockhound-detect-blocking-calls-in-reactive-code-before-its-too-late-6472f8ad50c1
*/
@log4j2
public class AllowBlockingIntegration implements BlockHoundIntegration {
@OverRide
public void applyTo(Builder builder) {
log.info("Applying {} Integrations ...", AllowBlockingIntegration.class.getSimpleName());
builder
.allowBlockingCallsInside(
"org.apache.maven.surefire.booter.ForkingRunListener",
"writeTestOutput")
.allowBlockingCallsInside("java.io.FileOutputStream",
"writeBytes")
.allowBlockingCallsInside("java.io.RandomAccessFile",
"readBytes");
log.info("{} Builder: {}", AllowBlockingIntegration.class.getSimpleName(), builder);
}
}

And in Junit 5 Test:
static {
// Block hound Initialization ... Available for existence of JVM ...
BlockHound.install( new AllowBlockingIntegration() );
}

Actual Behavior

The above is established with the 'AllowBlockingIntegration()' class and the other allows are working with the exception of the last for .allowBlockingCallsInside("java.io.RandomAccessFile",
"readBytes");

Full Stack Trace:

2020-07-29T14:44:52,895 INFO [reactor-http-nio-4] i.b.b.n.d.s.m.h.MaxAuthenticationHandler: Validating Access Token Request from remote:[Optional[/127.0.0.1:55286]] ...
2020-07-29T14:44:52,931 ERROR [reactor-http-nio-4] i.b.b.n.d.s.m.e.GlobalErrorAttributes: Processing Exception for request from: /127.0.0.1:55286 for /maxauth/api/v1/validate
2020-07-29T14:44:52,932 ERROR [reactor-http-nio-4] ....GlobalErrorAttributes: Runtime Exception Blocking call! java.io.RandomAccessFile#readBytes
reactor.blockhound.BlockingOperationError: Blocking call! java.io.RandomAccessFile#readBytes
at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java)
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
|_ checkpoint ? ....filter.CorsFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.cloud.sleuth.instrument.web.TraceWebFilter [DefaultWebFilterChain]
|_ checkpoint ? org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
|_ checkpoint ? HTTP GET "/maxauth/api/v1/validate" [ExceptionHandlingWebHandler]
Stack trace:
at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java)
at java.base/java.io.RandomAccessFile.read(RandomAccessFile.java:406)
at java.base/java.io.RandomAccessFile.readFully(RandomAccessFile.java:470)
at java.base/java.util.zip.ZipFile$Source.readFullyAt(ZipFile.java:1304)
at java.base/java.util.zip.ZipFile$ZipFileInputStream.initDataOffset(ZipFile.java:998)
at java.base/java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:1013)
at java.base/java.util.zip.ZipFile$ZipFileInflaterInputStream.fill(ZipFile.java:468)
at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:159)
at java.base/java.io.FilterInputStream.read(FilterInputStream.java:133)
at java.base/sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
at java.base/sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
at java.base/sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
at java.base/java.io.InputStreamReader.read(InputStreamReader.java:185)
at java.base/java.io.BufferedReader.fill(BufferedReader.java:161)
at java.base/java.io.BufferedReader.readLine(BufferedReader.java:326)
at java.base/java.io.BufferedReader.readLine(BufferedReader.java:392)
at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.parseLine(ServiceLoader.java:1129)
at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.parse(ServiceLoader.java:1169)
at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.nextProviderClass(ServiceLoader.java:1205)
at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.hasNextService(ServiceLoader.java:1220)
at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.hasNext(ServiceLoader.java:1264)
at java.base/java.util.ServiceLoader$2.hasNext(ServiceLoader.java:1299)
at java.base/java.util.ServiceLoader$3.hasNext(ServiceLoader.java:1384)
at java.base/java.util.Iterator.forEachRemaining(Iterator.java:132)
at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:558)
at com.okta.jwt.JwtVerifiers.loadService(JwtVerifiers.java:58)
at com.okta.jwt.JwtVerifiers.accessTokenVerifierBuilder(JwtVerifiers.java:51)
at ....okta.OktaAuthenticationServiceImpl.obtainTokenVerifier(OktaAuthenticationServiceImpl.java:194)
at ....okta.OktaAuthenticationServiceImpl.validateAccessToken(OktaAuthenticationServiceImpl.java:149)
at .... XXXAuthenticationHandler.validate(MaxAuthenticationHandler.java:169)
at org.springframework.web.reactive.function.server.support.HandlerFunctionAdapter.handle(HandlerFunctionAdapter.java:61)
at org.springframework.web.reactive.DispatcherHandler.invokeHandler(DispatcherHandler.java:161)
at org.springframework.web.reactive.DispatcherHandler.lambda$handle$1(DispatcherHandler.java:146)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:118)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:274)
at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:851)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:114)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:192)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:114)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:176)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:114)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:176)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:176)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:176)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onNext(FluxConcatArray.java:176)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2344)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.request(ScopePassingSpanSubscriber.java:76)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2152)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2026)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onSubscribe(ScopePassingSpanSubscriber.java:69)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:207)
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:207)
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:207)
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:207)
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:207)
at reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:80)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:441)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onNext(FluxConcatMap.java:243)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxIterable$IterableSubscription.slowPath(FluxIterable.java:267)
at reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:225)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.request(ScopePassingSpanSubscriber.java:76)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:228)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onSubscribe(ScopePassingSpanSubscriber.java:69)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at org.springframework.cloud.sleuth.instrument.web.TraceWebFilter$MonoWebFilterTrace.subscribe(TraceWebFilter.java:165)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4219)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
at reactor.netty.http.server.HttpServerHandle.onStateChange(HttpServerHandle.java:64)
at reactor.netty.ReactorNetty$CompositeConnectionObserver.onStateChange(ReactorNetty.java:514)
at reactor.netty.tcp.TcpServerBind$ChildObserver.onStateChange(TcpServerBind.java:267)
at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:465)
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:96)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:170)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296)
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)
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)
2020-07-29T14:44:52,952 DEBUG [reactor-http-nio-3] o.s.c.l.LogFormatUtils: [64b262a7] Response 400 BAD_REQUEST

Some class names obfuscated.

Steps to Reproduce

Could be difficult to reproduce, but attempt to use an Okta Library for JWT verification and that should lead you down the path.

It does not appear that you can allow the RandomAccessFile class methods, perhaps due to being native? Not sure.

            builder.allowBlockingCallsInside("java.io.RandomAccessFile",
                        "readBytes");

Possible Solution

Your Environment

Using:

SpringBoot 2.3.1 Base with WebFlex Starter
io.projectreactor.tools:blockhound:1.0.4.RELEASE
io.projectreactor.:reactor-test:3.3.6.RELEASE

Reactor version(s) used: 3.3.6
Other relevant libraries versions (eg. netty, ...): Yes, Netty being pulled in per Webflux Starter.
JVM version (javar -version):
$ java --version
openjdk 11.0.6 2020-01-14
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.6+10)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.6+10, mixed mode)
OS and version (eg uname -a):
$ uname -a
MINGW64_NT-10.0-18363 ******************** 3.0.7-338.x86_64 2019-11-21 23:07 UTC x86_64 Msys

Answer 1 · 2020-08-03T14:27:15.000Z

I have the same problem this forces me to disable blockhound 😓

You can reproduce it simply by doing a test on the any spring boot WebFlux handler.

You will have the following output:


reactor.blockhound.BlockingOperationError: Blocking call! java.io.RandomAccessFile#readBytes
	at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java)
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ HTTP GET "/api/v1/apikeys/foo" [ExceptionHandlingWebHandler]
Stack trace:
		at java.base/java.io.RandomAccessFile.readBytes(RandomAccessFile.java)
		at java.base/java.io.RandomAccessFile.read(RandomAccessFile.java:406)
		at java.base/java.io.RandomAccessFile.readFully(RandomAccessFile.java:470)
		at java.base/java.util.zip.ZipFile$Source.readFullyAt(ZipFile.java:1304)
		at java.base/java.util.zip.ZipFile$ZipFileInputStream.initDataOffset(ZipFile.java:998)
		at java.base/java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:1013)
		at java.base/java.util.zip.ZipFile$ZipFileInflaterInputStream.fill(ZipFile.java:468)
		at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:159)
		at java.base/java.io.InputStream.readNBytes(InputStream.java:490)
		at java.base/java.util.jar.JarFile.getBytes(JarFile.java:805)
		at java.base/java.util.jar.JarFile.checkForSpecialAttributes(JarFile.java:1005)
		at java.base/java.util.jar.JarFile.isMultiRelease(JarFile.java:388)
		at java.base/java.util.jar.JarFile.getEntry(JarFile.java:507)
		at java.base/sun.net.www.protocol.jar.URLJarFile.getEntry(URLJarFile.java:131)
		at java.base/sun.net.www.protocol.jar.JarURLConnection.connect(JarURLConnection.java:137)
		at java.base/sun.net.www.protocol.jar.JarURLConnection.getInputStream(JarURLConnection.java:155)
		at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.parse(ServiceLoader.java:1164)
		at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.nextProviderClass(ServiceLoader.java:1205)
		at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.hasNextService(ServiceLoader.java:1220)
		at java.base/java.util.ServiceLoader$LazyClassPathLookupIterator.hasNext(ServiceLoader.java:1264)
		at java.base/java.util.ServiceLoader$2.hasNext(ServiceLoader.java:1299)
		at java.base/java.util.ServiceLoader$3.hasNext(ServiceLoader.java:1384)
		at kotlin.sequences.SequencesKt___SequencesKt.toCollection(_Sequences.kt:722)
		at kotlin.sequences.SequencesKt___SequencesKt.toMutableList(_Sequences.kt:752)
		at kotlin.sequences.SequencesKt___SequencesKt.toList(_Sequences.kt:743)
		at kotlinx.coroutines.reactive.ReactiveFlowKt.<clinit>(ReactiveFlow.kt:147)
		at kotlinx.coroutines.reactive.AwaitKt.awaitOne(Await.kt:97)
		at kotlinx.coroutines.reactive.AwaitKt.awaitOne$default(Await.kt:95)
		at kotlinx.coroutines.reactive.AwaitKt.awaitSingle(Await.kt:81)
		at org.springframework.web.reactive.function.server.ServerResponseExtensionsKt.bodyValueAndAwait(ServerResponseExtensions.kt:63)
		at com.stack-labs.MyHandler.validate(MyHandler.kt:25)

Answer 2 · 2020-08-10T09:17:17.000Z

@jaschenk @davinkevin when you allow things, you allow a method containing the blocking call, not the call itself (hence the method's name, "allow blocking calls inside").

In your case, consider allowing java.util.ServiceLoader$LazyClassPathLookupIterator#parse.