Lightrun
question-mark
Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

Blocking call found with Spring Webflux and r2dbc-mysql driver.

See original GitHub issue

Overview

Hi, So I am using Spring Webflux 5.3.1(which internally uses Netty) and I am integrating it with a MySql R2DBC driver(r2dbc-mysql) to make a reactive application. It works fine and everything looks good. But when I tried to use BlockHound(a tool created by the Spring team to detect blocking calls), to make sure that my API is non-blocking end-to-end but it shows that there is a blocking call when I installed BlockHound.

Expected behavior

It should have run smoothly with/without BlockHound.

Actual behavior

BlockHound says that there is a blocking call. PFB the full stack trace and below it the part of stack trace where block hound tells the blocking call is.

2020-12-03 15:24:23,442 INFO  [main] o.s.b.w.e.n.NettyWebServer:109:[, ] - Netty started on port(s): 8080
2020-12-03 15:24:23,461 INFO  [main] c.m.d.DdReactiveApplication:61:[, ] - Started DdReactiveApplication in 3.946 seconds (JVM running for 4.569)
2020-12-03 15:24:35,151 ERROR [reactor-tcp-epoll-2] o.s.b.a.w.r.e.AbstractErrorWebExceptionHandler:122:[, ] - [f05df953-2]  500 Server Error for HTTP GET "/getAllExpFromDB"
org.springframework.dao.DataAccessResourceFailureException: executeMany; SQL [SELECT dd_reactive.* FROM dd_reactive]; null; nested exception is dev.miku.r2dbc.mysql.client.MySqlConnectionException
	at org.springframework.r2dbc.connection.ConnectionFactoryUtils.convertR2dbcException(ConnectionFactoryUtils.java:226)
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ Handler com.mmt.ddreactive.controller.DDController#getAllExperimentsFromDB(String) [DispatcherHandler]
	|_ checkpoint ⇢ HTTP GET "/getAllExpFromDB" [ExceptionHandlingWebHandler]
Stack trace:
		at org.springframework.r2dbc.connection.ConnectionFactoryUtils.convertR2dbcException(ConnectionFactoryUtils.java:226)
		at org.springframework.r2dbc.core.DefaultDatabaseClient.lambda$inConnectionMany$8(DefaultDatabaseClient.java:147)
		at reactor.core.publisher.Flux.lambda$onErrorMap$28(Flux.java:6579)
		at reactor.core.publisher.Flux.lambda$onErrorResume$29(Flux.java:6632)
		at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:94)
		at reactor.core.publisher.FluxUsingWhen$UsingWhenSubscriber.deferredError(FluxUsingWhen.java:411)
		at reactor.core.publisher.FluxUsingWhen$RollbackInner.onComplete(FluxUsingWhen.java:488)
		at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2018)
		at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:259)
		at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2018)
		at reactor.core.publisher.Operators$MonoSubscriber.onComplete(Operators.java:1826)
		at reactor.core.publisher.MonoIgnoreThen$ThenAcceptInner.onComplete(MonoIgnoreThen.java:323)
		at reactor.core.publisher.Operators$MonoSubscriber.onComplete(Operators.java:1826)
		at reactor.core.publisher.MonoIgnoreThen$ThenAcceptInner.onComplete(MonoIgnoreThen.java:323)
		at reactor.pool.SimpleDequePool$QueuePoolRecyclerInner.onComplete(SimpleDequePool.java:624)
		at reactor.core.publisher.Operators.complete(Operators.java:135)
		at reactor.core.publisher.MonoEmpty.subscribe(MonoEmpty.java:45)
		at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
		at reactor.pool.SimpleDequePool$QueuePoolRecyclerMono.subscribe(SimpleDequePool.java:736)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:154)
		at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:154)
		at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
		at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
		at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
		at reactor.core.publisher.MonoIgnoreElements$IgnoreElementsSubscriber.onError(MonoIgnoreElements.java:83)
		at reactor.core.publisher.FluxMap$MapSubscriber.onError(FluxMap.java:132)
		at reactor.core.publisher.FluxFilter$FilterSubscriber.onError(FluxFilter.java:157)
		at reactor.core.publisher.FluxFilter$FilterConditionalSubscriber.onError(FluxFilter.java:291)
		at reactor.core.publisher.FluxMap$MapConditionalSubscriber.onError(FluxMap.java:259)
		at reactor.core.publisher.Operators.error(Operators.java:196)
		at reactor.core.publisher.MonoError.subscribe(MonoError.java:52)
		at reactor.core.publisher.MonoDeferContextual.subscribe(MonoDeferContextual.java:55)
		at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
		at reactor.core.publisher.FluxUsingWhen$UsingWhenSubscriber.onError(FluxUsingWhen.java:377)
		at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:841)
		at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:607)
		at reactor.core.publisher.FluxFlatMap$FlatMapMain.drain(FluxFlatMap.java:587)
		at reactor.core.publisher.FluxFlatMap$FlatMapMain.onError(FluxFlatMap.java:450)
		at reactor.core.publisher.FluxMap$MapSubscriber.onError(FluxMap.java:132)
		at reactor.core.publisher.FluxMap$MapSubscriber.onError(FluxMap.java:132)
		at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.signalAsyncError(FluxWindowPredicate.java:341)
		at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.checkTerminated(FluxWindowPredicate.java:523)
		at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.drainLoop(FluxWindowPredicate.java:475)
		at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.drain(FluxWindowPredicate.java:419)
		at reactor.core.publisher.FluxWindowPredicate$WindowPredicateMain.onError(FluxWindowPredicate.java:278)
		at reactor.core.publisher.FluxHandleFuseable$HandleFuseableSubscriber.onError(FluxHandleFuseable.java:219)
		at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121)
		at dev.miku.r2dbc.mysql.util.DiscardOnCancelSubscriber.onError(DiscardOnCancelSubscriber.java:87)
		at reactor.core.publisher.FluxPeekFuseable$PeekConditionalSubscriber.onError(FluxPeekFuseable.java:903)
		at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onError(MonoFlatMapMany.java:255)
		at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:221)
		at reactor.core.publisher.FluxHandle$HandleSubscriber.onError(FluxHandle.java:202)
		at reactor.core.publisher.FluxPeekFuseable$PeekConditionalSubscriber.onError(FluxPeekFuseable.java:903)
		at reactor.core.publisher.EmitterProcessor.checkTerminated(EmitterProcessor.java:535)
		at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:402)
		at reactor.core.publisher.EmitterProcessor.tryEmitError(EmitterProcessor.java:238)
		at reactor.core.publisher.InternalManySink.emitError(InternalManySink.java:98)
		at reactor.core.publisher.EmitterProcessor.onError(EmitterProcessor.java:227)
		at dev.miku.r2dbc.mysql.client.ReactorNettyClient.drainError(ReactorNettyClient.java:254)
		at dev.miku.r2dbc.mysql.client.ReactorNettyClient.resumeError(ReactorNettyClient.java:214)
		at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:94)
		at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:221)
		at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:447)
		at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:256)
		at reactor.netty.channel.FluxReceive.onInboundError(FluxReceive.java:435)
		at reactor.netty.channel.ChannelOperations.onInboundError(ChannelOperations.java:467)
		at reactor.netty.channel.ChannelOperationsHandler.exceptionCaught(ChannelOperationsHandler.java:127)
		at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
		at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:281)
		at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:273)
		at io.netty.handler.ssl.SslHandler.exceptionCaught(SslHandler.java:1151)
		at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
		at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:752)
		at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
		at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
		at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)
		at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:439)
		at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:784)
		at reactor.core.publisher.FluxCreate$BufferAsyncSink.complete(FluxCreate.java:732)
		at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:240)
		at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:206)
		at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:197)
		at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onComplete(LargeMessageSlicer.java:99)
		at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2348)
		at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onSubscribe(LargeMessageSlicer.java:48)
		at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
		at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
		at dev.miku.r2dbc.mysql.message.client.LargeClientMessage.lambda$encode$0(LargeClientMessage.java:52)
		at reactor.core.publisher.FluxCreate.subscribe(FluxCreate.java:94)
		at reactor.core.publisher.Flux.subscribe(Flux.java:8095)
		at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.write(MessageDuplexCodec.java:111)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:764)
		at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1071)
		at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
		at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
		at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
		at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
		at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
		at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
		at java.lang.Thread.run(Thread.java:748)
Caused by: dev.miku.r2dbc.mysql.client.MySqlConnectionException: null
	at dev.miku.r2dbc.mysql.client.ClientExceptions.wrap(ClientExceptions.java:47)
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ SQL "SELECT dd_reactive.* FROM dd_reactive" [DatabaseClient]
Stack trace:
		at dev.miku.r2dbc.mysql.client.ClientExceptions.wrap(ClientExceptions.java:47)
		at dev.miku.r2dbc.mysql.client.ReactorNettyClient.resumeError(ReactorNettyClient.java:214)
		at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:94)
		at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:221)
		at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:447)
		at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:256)
		at reactor.netty.channel.FluxReceive.onInboundError(FluxReceive.java:435)
		at reactor.netty.channel.ChannelOperations.onInboundError(ChannelOperations.java:467)
		at reactor.netty.channel.ChannelOperationsHandler.exceptionCaught(ChannelOperationsHandler.java:127)
		at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
		at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:281)
		at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:273)
		at io.netty.handler.ssl.SslHandler.exceptionCaught(SslHandler.java:1151)
		at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
		at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:752)
		at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
		at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
		at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)
		at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:439)
		at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:784)
		at reactor.core.publisher.FluxCreate$BufferAsyncSink.complete(FluxCreate.java:732)
		at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:240)
		at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:206)
		at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:197)
		at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onComplete(LargeMessageSlicer.java:99)
		at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2348)
		at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onSubscribe(LargeMessageSlicer.java:48)
		at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
		at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
		at dev.miku.r2dbc.mysql.message.client.LargeClientMessage.lambda$encode$0(LargeClientMessage.java:52)
		at reactor.core.publisher.FluxCreate.subscribe(FluxCreate.java:94)
		at reactor.core.publisher.Flux.subscribe(Flux.java:8095)
		at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.write(MessageDuplexCodec.java:111)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
		at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:764)
		at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1071)
		at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
		at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
		at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
		at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
		at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
		at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
		at java.lang.Thread.run(Thread.java:748)
Caused by: reactor.blockhound.BlockingOperationError: Blocking call! java.io.FileInputStream#readBytes
	at java.io.FileInputStream.readBytes(FileInputStream.java)
	at java.io.FileInputStream.read(FileInputStream.java:255)
	at sun.security.provider.NativePRNG$RandomIO.readFully(NativePRNG.java:424)
	at sun.security.provider.NativePRNG$RandomIO.ensureBufferValid(NativePRNG.java:526)
	at sun.security.provider.NativePRNG$RandomIO.implNextBytes(NativePRNG.java:545)
	at sun.security.provider.NativePRNG$RandomIO.access$400(NativePRNG.java:331)
	at sun.security.provider.NativePRNG.engineNextBytes(NativePRNG.java:220)
	at java.security.SecureRandom.nextBytes(SecureRandom.java:468)
	at sun.security.ssl.CipherBox.createExplicitNonce(CipherBox.java:1025)
	at sun.security.ssl.EngineOutputRecord.write(EngineOutputRecord.java:287)
	at sun.security.ssl.EngineOutputRecord.write(EngineOutputRecord.java:225)
	at sun.security.ssl.EngineWriter.writeRecord(EngineWriter.java:186)
	at sun.security.ssl.SSLEngineImpl.writeRecord(SSLEngineImpl.java:1281)
	at sun.security.ssl.SSLEngineImpl.writeAppRecord(SSLEngineImpl.java:1252)
	at sun.security.ssl.SSLEngineImpl.wrap(SSLEngineImpl.java:1165)
	at javax.net.ssl.SSLEngine.wrap(SSLEngine.java:509)
	at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:1086)
	at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:843)
	at io.netty.handler.ssl.SslHandler.wrapAndFlush(SslHandler.java:811)
	at io.netty.handler.ssl.SslHandler.flush(SslHandler.java:792)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:750)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
	at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
	at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)
	at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:439)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:784)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.complete(FluxCreate.java:732)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:240)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:206)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:197)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onComplete(LargeMessageSlicer.java:99)
	at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2348)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onSubscribe(LargeMessageSlicer.java:48)
	at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
	at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
	at dev.miku.r2dbc.mysql.message.client.LargeClientMessage.lambda$encode$0(LargeClientMessage.java:52)
	at reactor.core.publisher.FluxCreate.subscribe(FluxCreate.java:94)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8095)
	at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.write(MessageDuplexCodec.java:111)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:764)
	at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1071)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
2020-12-03 15:24:35,195 WARN  [reactor-tcp-epoll-2] d.m.r.m.c.ReactorNettyClient:259:[, ] - Connection has been closed by peer
2020-12-03 15:24:35,196 ERROR [reactor-tcp-epoll-2] r.c.p.Operators:319:[, ] - Operator called default onErrorDropped
dev.miku.r2dbc.mysql.client.MySqlConnectionClosedException: Connection unexpectedly closed
	at dev.miku.r2dbc.mysql.client.ClientExceptions.unexpectedClosed(ClientExceptions.java:32)
	at dev.miku.r2dbc.mysql.client.ReactorNettyClient.handleClose(ReactorNettyClient.java:260)
	at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:264)
	at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2018)
	at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:366)
	at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onComplete(FluxConcatMap.java:275)
	at reactor.core.publisher.EmitterProcessor.checkTerminated(EmitterProcessor.java:541)
	at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:402)
	at reactor.core.publisher.EmitterProcessor.tryEmitComplete(EmitterProcessor.java:221)
	at reactor.core.publisher.EmitterProcessor.onComplete(EmitterProcessor.java:212)
	at dev.miku.r2dbc.mysql.client.ReactorNettyClient.resumeError(ReactorNettyClient.java:215)
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:94)
	at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:221)
	at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:447)
	at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:256)
	at reactor.netty.channel.FluxReceive.onInboundError(FluxReceive.java:435)
	at reactor.netty.channel.ChannelOperations.onInboundError(ChannelOperations.java:467)
	at reactor.netty.channel.ChannelOperationsHandler.exceptionCaught(ChannelOperationsHandler.java:127)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:281)
	at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:273)
	at io.netty.handler.ssl.SslHandler.exceptionCaught(SslHandler.java:1151)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:752)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
	at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
	at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)
	at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:439)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:784)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.complete(FluxCreate.java:732)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:240)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:206)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:197)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onComplete(LargeMessageSlicer.java:99)
	at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2348)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onSubscribe(LargeMessageSlicer.java:48)
	at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
	at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
	at dev.miku.r2dbc.mysql.message.client.LargeClientMessage.lambda$encode$0(LargeClientMessage.java:52)
	at reactor.core.publisher.FluxCreate.subscribe(FluxCreate.java:94)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8095)
	at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.write(MessageDuplexCodec.java:111)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:764)
	at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1071)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.lang.Thread.run(Thread.java:748)
2020-12-03 15:24:35,197 ERROR [reactor-tcp-epoll-2] d.m.r.m.c.ReactorNettyClient:217:[, ] - Error: Blocking call! java.io.FileInputStream#readBytes
reactor.blockhound.BlockingOperationError: Blocking call! java.io.FileInputStream#readBytes
	at java.io.FileInputStream.readBytes(FileInputStream.java)
	at java.io.FileInputStream.read(FileInputStream.java:255)
	at sun.security.provider.NativePRNG$RandomIO.readFully(NativePRNG.java:424)
	at sun.security.provider.NativePRNG$RandomIO.ensureBufferValid(NativePRNG.java:526)
	at sun.security.provider.NativePRNG$RandomIO.implNextBytes(NativePRNG.java:545)
	at sun.security.provider.NativePRNG$RandomIO.access$400(NativePRNG.java:331)
	at sun.security.provider.NativePRNG.engineNextBytes(NativePRNG.java:220)
	at java.security.SecureRandom.nextBytes(SecureRandom.java:468)
	at sun.security.ssl.CipherBox.createExplicitNonce(CipherBox.java:1025)
	at sun.security.ssl.EngineOutputRecord.write(EngineOutputRecord.java:287)
	at sun.security.ssl.EngineOutputRecord.write(EngineOutputRecord.java:225)
	at sun.security.ssl.EngineWriter.writeRecord(EngineWriter.java:186)
	at sun.security.ssl.SSLEngineImpl.writeRecord(SSLEngineImpl.java:1281)
	at sun.security.ssl.SSLEngineImpl.writeAppRecord(SSLEngineImpl.java:1252)
	at sun.security.ssl.SSLEngineImpl.wrap(SSLEngineImpl.java:1165)
	at javax.net.ssl.SSLEngine.wrap(SSLEngine.java:509)
	at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:1086)
	at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:843)
	at io.netty.handler.ssl.SslHandler.wrapAndFlush(SslHandler.java:811)
	at io.netty.handler.ssl.SslHandler.flush(SslHandler.java:792)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:750)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
	at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
	at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)
	at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:439)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:784)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.complete(FluxCreate.java:732)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:240)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:206)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:197)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onComplete(LargeMessageSlicer.java:99)
	at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2348)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onSubscribe(LargeMessageSlicer.java:48)
	at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
	at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
	at dev.miku.r2dbc.mysql.message.client.LargeClientMessage.lambda$encode$0(LargeClientMessage.java:52)
	at reactor.core.publisher.FluxCreate.subscribe(FluxCreate.java:94)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8095)
	at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.write(MessageDuplexCodec.java:111)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:764)
	at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1071)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
	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.lang.Thread.run(Thread.java:748)
2020-12-03 15:24:35,207 ERROR [reactor-tcp-epoll-2] r.c.p.Operators:319:[, ] - Operator called default onErrorDropped
dev.miku.r2dbc.mysql.client.MySqlConnectionClosedException: Connection closed
	at dev.miku.r2dbc.mysql.client.ClientExceptions.expectedClosed(ClientExceptions.java:36)
	at dev.miku.r2dbc.mysql.client.ReactorNettyClient.handleClose(ReactorNettyClient.java:262)
	at dev.miku.r2dbc.mysql.client.ReactorNettyClient.access$400(ReactorNettyClient.java:53)
	at dev.miku.r2dbc.mysql.client.ReactorNettyClient$ResponseSubscriber.onComplete(ReactorNettyClient.java:306)
	at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2018)
	at reactor.core.publisher.Operators$MonoSubscriber.onComplete(Operators.java:1826)
	at reactor.core.publisher.MonoIgnoreThen$ThenAcceptInner.onComplete(MonoIgnoreThen.java:323)
	at reactor.core.publisher.Operators.complete(Operators.java:135)
	at reactor.netty.FutureMono$DeferredFutureMono.subscribe(FutureMono.java:131)
	at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:154)
	at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
	at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
	at reactor.core.publisher.FluxPeek$PeekSubscriber.onError(FluxPeek.java:221)
	at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:447)
	at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:256)
	at reactor.netty.channel.FluxReceive.onInboundError(FluxReceive.java:435)
	at reactor.netty.channel.ChannelOperations.onInboundError(ChannelOperations.java:467)
	at reactor.netty.channel.ChannelOperationsHandler.exceptionCaught(ChannelOperationsHandler.java:127)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:281)
	at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:273)
	at io.netty.handler.ssl.SslHandler.exceptionCaught(SslHandler.java:1151)
	at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:302)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:752)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
	at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
	at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)
	at reactor.core.publisher.FluxCreate$BaseSink.complete(FluxCreate.java:439)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:784)
	at reactor.core.publisher.FluxCreate$BufferAsyncSink.complete(FluxCreate.java:732)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drainLoop(FluxCreate.java:240)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.drain(FluxCreate.java:206)
	at reactor.core.publisher.FluxCreate$SerializedFluxSink.complete(FluxCreate.java:197)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onComplete(LargeMessageSlicer.java:99)
	at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2348)
	at dev.miku.r2dbc.mysql.message.client.LargeMessageSlicer.onSubscribe(LargeMessageSlicer.java:48)
	at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
	at reactor.core.publisher.Mono.subscribe(Mono.java:3987)
	at dev.miku.r2dbc.mysql.message.client.LargeClientMessage.lambda$encode$0(LargeClientMessage.java:52)
	at reactor.core.publisher.FluxCreate.subscribe(FluxCreate.java:94)
	at reactor.core.publisher.Flux.subscribe(Flux.java:8095)
	at dev.miku.r2dbc.mysql.client.MessageDuplexCodec.write(MessageDuplexCodec.java:111)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
	at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:764)
	at io.netty.channel.AbstractChannelHandlerContext$WriteTask.run(AbstractChannelHandlerContext.java:1071)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)
	at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:384)
	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.lang.Thread.run(Thread.java:748)

Part of stack trace where blockhound found the blocking call:

2020-12-03 15:24:35,197 ERROR [reactor-tcp-epoll-2] d.m.r.m.c.ReactorNettyClient:217:[, ] - Error: Blocking call! java.io.FileInputStream#readBytes
reactor.blockhound.BlockingOperationError: Blocking call! java.io.FileInputStream#readBytes
	at java.io.FileInputStream.readBytes(FileInputStream.java)
	at java.io.FileInputStream.read(FileInputStream.java:255)
	at sun.security.provider.NativePRNG$RandomIO.readFully(NativePRNG.java:424)
	at sun.security.provider.NativePRNG$RandomIO.ensureBufferValid(NativePRNG.java:526)
	at sun.security.provider.NativePRNG$RandomIO.implNextBytes(NativePRNG.java:545)
	at sun.security.provider.NativePRNG$RandomIO.access$400(NativePRNG.java:331)
	at sun.security.provider.NativePRNG.engineNextBytes(NativePRNG.java:220)
	at java.security.SecureRandom.nextBytes(SecureRandom.java:468)
	at sun.security.ssl.CipherBox.createExplicitNonce(CipherBox.java:1025)
	at sun.security.ssl.EngineOutputRecord.write(EngineOutputRecord.java:287)
	at sun.security.ssl.EngineOutputRecord.write(EngineOutputRecord.java:225)
	at sun.security.ssl.EngineWriter.writeRecord(EngineWriter.java:186)
	at sun.security.ssl.SSLEngineImpl.writeRecord(SSLEngineImpl.java:1281)
	at sun.security.ssl.SSLEngineImpl.writeAppRecord(SSLEngineImpl.java:1252)
	at sun.security.ssl.SSLEngineImpl.wrap(SSLEngineImpl.java:1165)
	at javax.net.ssl.SSLEngine.wrap(SSLEngine.java:509)
	at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:1086)
	at io.netty.handler.ssl.SslHandler.wrap(SslHandler.java:843)
	at io.netty.handler.ssl.SslHandler.wrapAndFlush(SslHandler.java:811)
	at io.netty.handler.ssl.SslHandler.flush(SslHandler.java:792)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:750)
	at io.netty.channel.AbstractChannelHandlerContext.invokeFlush(AbstractChannelHandlerContext.java:742)
	at io.netty.channel.AbstractChannelHandlerContext.flush(AbstractChannelHandlerContext.java:728)
	at dev.miku.r2dbc.mysql.client.WriteSubscriber.onComplete(WriteSubscriber.java:72)

Steps to reproduce

I made a few DB calls here and there and was able to produce the blockhound exception, an overview of what I did was, first I hit an API which fetched few rows from a table from DB using the @Query(“select * from dd_reactive where id in (:listOfIds)”) (without blockhound) this works fine, then I hit another API which made another call to DB to fetch all the rows of the table (with blockhound), it breaks here with the stack trace pasted above.

Minimal yet complete reproducer code (or URL to code)

If needed I can provide the code later on.

Netty version

4.1.54.Final

JVM version (e.g. java -version)

Oracle JDK java version “1.8.0_231” Java™ SE Runtime Environment (build 1.8.0_231-b11) Java HotSpot™ 64-Bit Server VM (build 25.231-b11, mixed mode)

OS version (e.g. uname -a)

Linux mmt-ubt-8341 5.4.0-53-generic #59~18.04.1-Ubuntu SMP Wed Oct 21 12:14:56 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

P.S.: First I thought it was due to the R2DBC MySQL driver(r2dbc-mysql) I was using and I raised it in their github issues, but they suggested me that it isn’t on their side but on Netty’s side. Issue Link: https://github.com/mirromutth/r2dbc-mysql/issues/153

Issue Analytics

  • State:closed
  • Created 3 years ago
  • Comments:5 (5 by maintainers)

github_iconTop GitHub Comments

1reaction
violetaggcommented, Dec 4, 2020

@chrisvest Isn’t it related to unwrap and not wrap

            builder.allowBlockingCallsInside(
                    "sun.security.ssl.SSLEngineImpl",
                    "unwrap");
0reactions
violetaggcommented, Dec 4, 2020

@violetagg are you interested in providing a PR ?

ok

Read more comments on GitHub >

github_iconTop Results From Across the Web

Spring Data R2DBC - Reference Documentation
In synchronous, imperative code, blocking calls serve as a natural form of back pressure that forces the caller to wait. In non-blocking code, ......
Read more >
Transactions in webflux with blocking spring data
You can implement a separate transaction layer with blocking update methods to DB, like: class TransactionRepo { private TransactionTemplate ...
Read more >
Unblock Your Applications with R2DBC, Spring Data and ...
The MariaDB Connector/R2DBC is now GA. This blog walks you through how to create a fully-reactive Maven-based Java application with Spring ...
Read more >
Reactive programming with Spring Data R2DBC - Medium
How to build a collaborative web application with Angular, Spring Boot, Spring WebFlux, Spring Data R2DBC and PostgreSQL.
Read more >
Spring WebFlux Reactive Repository using R2DBC - PART-3
Why we need Reactive Repository. All the database calls using JDBC drivers are blocking in nature. That means a thread that calls the...
Read more >

github_iconTop Related Medium Post

No results found

github_iconTop Related StackOverflow Question

No results found

github_iconTroubleshoot Live Code

Lightrun enables developers to add logs, metrics and snapshots to live code - no restarts or redeploys required.
Start Free

github_iconTop Related Reddit Thread

No results found

github_iconTop Related Hackernoon Post

No results found

github_iconTop Related Tweet

No results found

github_iconTop Related Dev.to Post

No results found

github_iconTop Related Hashnode Post

No results found
Previous page

Could not find netty-transport-native-epoll-4.1.57.Final-SNAPSHOT-linux-x86_64.jar

Next page

Channel#writeAndFlush method costly