Spring LEAK: ByteBuf.release() was not called before it's garbage-collected

Getting memory leak issue while using spring webflux + netty. We are facing this issue during high requests.

Here is complete stack trace:

{"timestamp":1712654400358,"thread":"reactor-http-epoll-27","logger":"io.netty.util.ResourceLeakDetector","message":"LEAK: ByteBuf.release() was not called before it's garbage-collected. See https://netty.io/wiki/reference-counted-objects.html for more information.
Recent access records: 
Created at:
    io.netty.buffer.PooledByteBufAllocator.newDirectBuffer(PooledByteBufAllocator.java:404)
    io.netty.buffer.AbstractByteBufAllocator.directBuffer(AbstractByteBufAllocator.java:188)
    io.netty.buffer.AbstractByteBufAllocator.directBuffer(AbstractByteBufAllocator.java:179)
    io.netty.buffer.AbstractByteBufAllocator.buffer(AbstractByteBufAllocator.java:116)
    org.springframework.core.io.buffer.NettyDataBufferFactory.allocateBuffer(NettyDataBufferFactory.java:72)
    org.springframework.core.io.buffer.NettyDataBufferFactory.allocateBuffer(NettyDataBufferFactory.java:39)
    org.springframework.core.codec.CharSequenceEncoder.encodeValue(CharSequenceEncoder.java:90)
    org.springframework.core.codec.CharSequenceEncoder.lambda$encode$0(CharSequenceEncoder.java:74)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:113)
    reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2571)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:171)
    reactor.core.publisher.MonoSingle$SingleSubscriber.doOnRequest(MonoSingle.java:103)
    reactor.core.publisher.Operators$MonoInnerProducerBase.request(Operators.java:2909)
    reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2367)
    reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2241)
    reactor.core.publisher.MonoSingle$SingleSubscriber.onSubscribe(MonoSingle.java:115)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96)
    reactor.core.publisher.FluxJust.subscribe(FluxJust.java:68)
    reactor.core.publisher.Mono.subscribe(Mono.java:4568)
    reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:202)
    reactor.core.publisher.MonoFlatMap.subscribeOrReturn(MonoFlatMap.java:53)
    reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:63)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:165)
    reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:158)
    reactor.core.publisher.MonoZip$ZipCoordinator.signal(MonoZip.java:297)
    reactor.core.publisher.MonoZip$ZipInner.onNext(MonoZip.java:478)
    reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2571)
    reactor.core.publisher.MonoZip$ZipInner.onSubscribe(MonoZip.java:470)
    reactor.core.publisher.MonoJust.subscribe(MonoJust.java:55)
    reactor.core.publisher.MonoZip$ZipCoordinator.request(MonoZip.java:220)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:194)
    reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2367)
    reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onSubscribe(FluxOnErrorResume.java:74)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:117)
    reactor.core.publisher.MonoZip.subscribe(MonoZip.java:129)
    reactor.core.publisher.Mono.subscribe(Mono.java:4568)
    reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
    reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:544)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError(MonoFlatMap.java:241)
    reactor.core.publisher.MonoFlatMap$FlatMapInner.onError(MonoFlatMap.java:315)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121)
    reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onError(MonoPeekTerminal.java:258)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError(MonoFlatMap.java:241)
    reactor.core.publisher.MonoFlatMap$FlatMapInner.onError(MonoFlatMap.java:315)
    reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onError(FluxPeekFuseable.java:234)
    reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onError(MonoPeekTerminal.java:258)
    reactor.core.publisher.MonoIgnoreElements$IgnoreElementsSubscriber.onError(MonoIgnoreElements.java:84)
    reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onError(FluxConcatArray.java:208)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:149)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)
    reactor.core.publisher.FluxPeekFuseable$PeekFuseableConditionalSubscriber.onNext(FluxPeekFuseable.java:503)
    reactor.core.publisher.MonoCallable$MonoCallableSubscription.request(MonoCallable.java:156)
    reactor.core.publisher.FluxPeekFuseable$PeekFuseableConditionalSubscriber.request(FluxPeekFuseable.java:437)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.request(FluxContextWrite.java:136)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:171)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:194)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.request(FluxContextWrite.java:136)
    reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onSubscribe(FluxConcatArray.java:194)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onSubscribe(FluxContextWrite.java:101)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:117)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onSubscribe(FluxContextWrite.java:101)
    reactor.core.publisher.FluxPeekFuseable$PeekFuseableConditionalSubscriber.onSubscribe(FluxPeekFuseable.java:471)
    reactor.core.publisher.MonoCallable.subscribe(MonoCallable.java:48)
    reactor.core.publisher.Mono.subscribe(Mono.java:4568)
    reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:260)
    reactor.core.publisher.FluxConcatArray.subscribe(FluxConcatArray.java:79)
    reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:165)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)
    reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2571)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.request(FluxContextWrite.java:136)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.request(MonoFlatMap.java:194)
    reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.request(MonoPeekTerminal.java:139)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.request(FluxContextWrite.java:136)
    reactor.core.publisher.MonoFlatMap$FlatMapInner.onSubscribe(MonoFlatMap.java:291)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onSubscribe(FluxContextWrite.java:101)
    reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onSubscribe(MonoPeekTerminal.java:152)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:117)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onSubscribe(FluxContextWrite.java:101)
    reactor.core.publisher.MonoJust.subscribe(MonoJust.java:55)
    reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:165)
    reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:74)
    reactor.core.publisher.Operators$MonoInnerProducerBase.complete(Operators.java:2842)
    reactor.core.publisher.MonoSingle$SingleSubscriber.onComplete(MonoSingle.java:180)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onComplete(FluxMapFuseable.java:152)
    reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2573)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:171)
    reactor.core.publisher.MonoSingle$SingleSubscriber.doOnRequest(MonoSingle.java:103)
    reactor.core.publisher.Operators$MonoInnerProducerBase.request(Operators.java:2909)
    reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2367)
    reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:2241)
    reactor.core.publisher.MonoSingle$SingleSubscriber.onSubscribe(MonoSingle.java:115)
    reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96)
    reactor.core.publisher.FluxJust.subscribe(FluxJust.java:68)
    reactor.core.publisher.Mono.subscribe(Mono.java:4568)
    reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:202)
    reactor.core.publisher.MonoFlatMap.subscribeOrReturn(MonoFlatMap.java:53)
    reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:63)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:165)
    reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)
    reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)
    reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:200)
    reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.complete(MonoIgnoreThen.java:294)
    reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.onNext(MonoIgnoreThen.java:188)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:158)
    reactor.core.publisher.MonoZip$ZipCoordinator.signal(MonoZip.java:297)
    reactor.core.publisher.MonoZip$ZipInner.onNext(MonoZip.java:478)
    reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:180)
    reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:122)
    reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:74)
    reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)
    reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:158)
    reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)
    reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:299)
    reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:337)
    reactor.core.publisher.Operators$BaseFluxToMonoOperator.completePossiblyEmpty(Operators.java:2097)
    reactor.core.publisher.MonoCollect$CollectSubscriber.onComplete(MonoCollect.java:145)
    reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144)
    reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:260)
    reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144)
    reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:415)
    reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:446)
    reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:687)
    reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:114)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
    reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:284)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)
    io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346)
    io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318)
    io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)
    io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)
    io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)
    io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
    io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:800)
    io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:509)
    io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:407)
    io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997)
    io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)

Java version: 17 Spring boot version: 3.2.4 JVM args passed:

-XX:MaxDirectMemorySize=1024M
-Dio.netty.leakDetection.targetRecords=40
-Dio.netty.leakDetection.level=ADVANCED
-Dlogging.level._reactor.netty.channel.LeakDetection=debug

Comment From: snicoll

Can you please share a small sample that reproduces the issue? You can attach a zip to this issue or push the code to a GitHub repository.

Comment From: subham611

github_sample_code.zip attached sample code

Comment From: snicoll

@subham611 thanks but putting a text file in a zip does not qualify as a sample. Please share a sample we can run ourselves to reproduce the problem.

Comment From: spring-projects-issues

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

Comment From: spring-projects-issues

Closing due to lack of requested feedback. If you would like us to look at this issue, please provide the requested information and we will re-open the issue.