IllegalReferenceCountException - "Failed to release a message: PooledSlicedByteBuf(freed)"

When I execute the following code, I get the error message mentioned in the title (and below).

It only happens when not registering an error handler for a flux that actually throws an exception.

Anyway, this might cause severe problems (memory leak?), so I thought I would mention it.

Expected Behavior

No IllegalReferenceCountException

Actual Behavior

Exception and error log.

02-06-2020 19:07:25.228 [reactor-tcp-nio-2] WARN  i.n.u.ReferenceCountUtil - Failed to release a message: PooledSlicedByteBuf(freed)
io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1
	at io.netty.util.internal.ReferenceCountUpdater.toLiveRealRefCnt(ReferenceCountUpdater.java:74)
	at io.netty.util.internal.ReferenceCountUpdater.release(ReferenceCountUpdater.java:138)
	at io.netty.buffer.AbstractReferenceCountedByteBuf.release(AbstractReferenceCountedByteBuf.java:100)
	at io.netty.util.ReferenceCountUtil.release(ReferenceCountUtil.java:88)
	at io.netty.util.ReferenceCountUtil.safeRelease(ReferenceCountUtil.java:113)
	at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:109)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
	at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:321)
	at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:295)
	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:832)

Steps to Reproduce

Sorry for this not being a real unit test, but you will get the idea.

@Test
public void asdf() throws Exception {
	CloseableChannel server = RSocketServer.create((setup, sendingRSocket) -> Mono.just(new RSocket() {
		@Override
		public Flux<Payload> requestStream(Payload payload) {
			if (payload.getDataUtf8().equals("flux")) {
				return Flux.interval(Duration.ofMillis(1))
						.doOnNext(aLong -> System.out.println("Server-side doOnNext: " + aLong))
						.doOnCancel(() -> System.out.println("Server-side doOnCancel"))
						.map(aLong -> DefaultPayload.create("" + aLong));
			} else {
				return Flux.error(new RuntimeException("Some Exception for this test"));
			}
		}
	}))
			.bind(TcpServerTransport.create(TcpServer.create().host("localhost").port(7890)))
			.block();

	RSocket client = RSocketConnector.create()
			.connect(TcpClientTransport.create(TcpClient.create().host("localhost").port(7890)))
			.block();

	client.requestStream(DefaultPayload.create("exception"))
			.take(10)
			.subscribe(payload -> System.out.println(payload.getDataUtf8()));  // Note: no error handler!

	Thread.sleep(1000);
}

Possible Solution

Your Environment

• RSocket version(s) used: 1.0.0
• Other relevant libraries versions (eg. netty, …): default rsocket dependencies
• Platform (eg. JVM version (javar -version) or Node version (node --version)): openjdk 14.0.1 2020-04-14 OpenJDK Runtime Environment AdoptOpenJDK (build 14.0.1+7) OpenJDK 64-Bit Server VM AdoptOpenJDK (build 14.0.1+7, mixed mode, sharing)
• OS and version (eg uname -a): MacOS

[OlegDokuka]

A fix for #858 will be provided but we are not sure how the ByteBuf double release may be related to the error-handler issue since the unite test provided is not reproducing it.

Therefore, once #858 is fixed, please double check this one and if it is not reproducing anyhow or reproduces with another test, please provide extra input if you want us to continue working on this.

Cheers, Oleh

[OlegDokuka]

Closed because of lack of information