LEAK: 未调用ByteBuf.release() – 我们如何解决这个问题？

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英文:

LEAK: ByteBuf.release() was not called - how do we solve this?

问题

这是您提供的内容的翻译：

我们有一个基于Netty的网络流量密集型Java应用程序/服务器。

附注：我主要支持这个应用程序，我没有构建它，所以我不完全了解它。

我们有时会出现下面显示的错误。以前，我们在服务器运行了3-4天后才会出现这个错误。现在我注意到，即使在重新启动服务器/应用程序后的10-15分钟内，我们也会遇到这个错误。

我不明白这是怎么可能的。这个错误是否令人担忧，我们该如何修复它？我记得以前曾对这个错误进行了广泛的研究，当时我甚至尝试过升级和修补Netty，但没有任何帮助完全解决这个问题。

操作系统：Linux
Java版本：1.8
Netty版本：netty-all-4.1.30.Final.jar

这是唯一的应用程序特定代码行，其他所有操作都在Netty中进行。

com.company.japp.protocol.http.decoders.ConditionalHttpChunkAggregator.channelRead

这是否是Netty本身的某种错误？Netty的升级或任何其他配置调整是否有助于解决这个问题？

[2020-09-04 08:33:53,072]

错误

io.netty.util.ResourceLeakDetector

LEAK：在垃圾回收之前未调用ByteBuf.release()。

有关更多信息，请参见https://netty.io/wiki/reference-counted-objects.html。

最近的访问记录：
创建于：
io.netty.buffer.AbstractByteBufAllocator.compositeDirectBuffer(AbstractByteBufAllocator.java:221)
io.netty.buffer.AbstractByteBufAllocator.compositeBuffer(AbstractByteBufAllocator.java:199)
io.netty.handler.codec.MessageAggregator.decode(MessageAggregator.java:255)
io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:88)
com.company.japp.protocol.http.decoders.ConditionalHttpChunkAggregator.channelRead(ConditionalHttpChunkAggregator.java:112)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:323)
io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:297)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965)
io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:644)
io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:579)
io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:496)
io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:458)
io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:897)
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
java.lang.Thread.run(Thread.java:748)

这是ConditionalHttpChunkAggregator的代码：

package com.company.japp.protocol.http.decoders;

import com.company.japp.IHttpProxyServer;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpMessage;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.util.HashSet;

@ChannelHandler.Sharable
public class ConditionalHttpChunkAggregator extends HttpObjectAggregator {
    private static final InternalLogger logger = InternalLoggerFactory.getInstance(ConditionalHttpChunkAggregator.class);

    private volatile boolean sendaschunked;
    private volatile int maxContentLength;

    private static IHttpProxyServer iHttpProxyServer;

    public static void initialize(IHttpProxyServer iHttpProxyServer) {
        ConditionalHttpChunkAggregator.iHttpProxyServer = iHttpProxyServer;
    }

    public ConditionalHttpChunkAggregator(int maxContentLength) {
        super(maxContentLength);
        this.maxContentLength = maxContentLength;
        sendaschunked = false;
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg){
        if ((msg instanceof HttpResponse)) {
            HttpResponse response = (HttpResponse)msg;
            if ((msg instanceof HttpMessage)) {
                HttpMessage httpmessage= (HttpMessage)msg;

                try  {
                    // If the content length exceeds the threshhold, then send it as chunked
                    // It's too large to process substitutions
                    Long contentlength = 
                    		httpmessage.headers().get(HttpHeaders.Names.CONTENT_LENGTH) != null ? 
                    		Long.valueOf(httpmessage.headers().get(HttpHeaders.Names.CONTENT_LENGTH)) : -1;
                    if (contentlength >= maxContentLength) {
                        sendaschunked = true;
                    } else {
                    // Check content types
                         HashSet<String> chunkabletypes = iHttpProxyServer.getConfig().getProperty("chunkabletypes");
                        if (!chunkabletypes.isEmpty() && response.headers().contains(HttpHeaders.Names.CONTENT_TYPE)) {
                            String contentType = response.headers().get(HttpHeaders.Names.CONTENT_TYPE).toLowerCase().trim();
                            if (contentType.length()>0) {
                                sendaschunked = chunkabletypes.contains(contentType);
                                if (!sendaschunked) {
                                    for (String chunkabletype: chunkabletypes) {
                                        // Begins with
                                        if (contentType.indexOf(chunkabletype)==0) {
                                            sendaschunked = true;
                                            break;
                                        }
                                    }
                                }
                            }
                        }
                    }
                    if (sendaschunked) {
                        ctx.fireChannelRead(msg);
                        return;
                    }
                }
                catch(Exception ex) {
                    logger.error("error determining chunkable viability", ex);
                }
           

<details>
<summary>英文:</summary>

We have a netty-based network traffic intensive Java app/server.   

*Side note: I mainly support this app, I didn&#39;t build it so I don&#39;t know it in full.*       

We sometimes get this error as shown below. Previously we used to get this error after the server has been up for 3-4 days. Now I noticed that we are getting this error even just 10-15 mins after rebooting the server/app.     

I don&#39;t understand how this is possible. Is this error something worrying and how can we fix it? I recall doing extensive research in the past on this same error, back then I even tried upgrading and patching netty but nothing helped to fully resolve the issue.

OS: Linux     
Java version: 1.8      
Netty version: netty-all-4.1.30.Final.jar      

This is the only line of app-specific code, everything else happens in Netty.    

`com.company.japp.protocol.http.decoders.ConditionalHttpChunkAggregator.channelRead`  

Is this a bug of some sort in Netty itself? Would Netty upgrade or any other configuration tuning help here?

	[2020-09-04 08:33:53,072]
	
	ERROR
	
	io.netty.util.ResourceLeakDetector
	
	LEAK: ByteBuf.release() was not called before it&#39;s garbage-collected. 
	
	See https://netty.io/wiki/reference-counted-objects.html for more information.
	
	Recent access records: 
	Created at:
		io.netty.buffer.AbstractByteBufAllocator.compositeDirectBuffer(AbstractByteBufAllocator.java:221)
		io.netty.buffer.AbstractByteBufAllocator.compositeBuffer(AbstractByteBufAllocator.java:199)
		io.netty.handler.codec.MessageAggregator.decode(MessageAggregator.java:255)
		io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:88)
		com.company.japp.protocol.http.decoders.ConditionalHttpChunkAggregator.channelRead(ConditionalHttpChunkAggregator.java:112)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
		io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
		io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:323)
		io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:297)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
		io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
		io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
		io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
		io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
		io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
		io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965)
		io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
		io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:644)
		io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:579)
		io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:496)
		io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:458)
		io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:897)
		io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
		java.lang.Thread.run(Thread.java:748)
	
	
	
	
Here is the code for the `ConditionalHttpChunkAggregator`.    


	package com.company.japp.protocol.http.decoders;
	
	import com.company.japp.IHttpProxyServer;
	import io.netty.channel.ChannelDuplexHandler;
	import io.netty.channel.ChannelHandler;
	import io.netty.channel.ChannelHandlerContext;
	import io.netty.handler.codec.http.HttpHeaders;
	import io.netty.handler.codec.http.HttpMessage;
	import io.netty.handler.codec.http.HttpObjectAggregator;
	import io.netty.handler.codec.http.HttpResponse;
	import io.netty.util.internal.logging.InternalLogger;
	import io.netty.util.internal.logging.InternalLoggerFactory;
	
	import java.util.HashSet;
	
	@ChannelHandler.Sharable
	public class ConditionalHttpChunkAggregator extends HttpObjectAggregator {
	    private static final InternalLogger logger = InternalLoggerFactory.getInstance(ConditionalHttpChunkAggregator.class);
	
	    private volatile boolean        sendaschunked;
	    private volatile int        maxContentLength;
	
	    private static IHttpProxyServer         iHttpProxyServer;
	
	    public static void initialize(IHttpProxyServer iHttpProxyServer) {
	        ConditionalHttpChunkAggregator.iHttpProxyServer = iHttpProxyServer;
	    }
	
	    public ConditionalHttpChunkAggregator(int maxContentLength) {
	        super(maxContentLength);
	        this.maxContentLength = maxContentLength;
	        sendaschunked = false;
	    }
	
	    @Override
	    public void channelRead(ChannelHandlerContext ctx, Object msg){
	        if ((msg instanceof HttpResponse)) {
	            HttpResponse response = (HttpResponse)msg;
	            if ((msg instanceof HttpMessage)) {
	                HttpMessage httpmessage= (HttpMessage)msg;
	
	                try  {
	                    // If the content length exceeds the threshhold, then send it as chunked
	                    // It&#39;s too large to process substitutions
	                    Long contentlength = 
	                    		httpmessage.headers().get(HttpHeaders.Names.CONTENT_LENGTH) != null ? 
	                    		Long.valueOf(httpmessage.headers().get(HttpHeaders.Names.CONTENT_LENGTH)) : -1;
	                    if (contentlength &gt;= maxContentLength) {
	                        sendaschunked = true;
	                    } else {
	                    // Check content types
	                         HashSet&lt;String&gt; chunkabletypes = iHttpProxyServer.getConfig().getProperty(&quot;chunkabletypes&quot;);
	                        if (!chunkabletypes.isEmpty() &amp;&amp; response.headers().contains(HttpHeaders.Names.CONTENT_TYPE)) {
	                            String contentType = response.headers().get(HttpHeaders.Names.CONTENT_TYPE).toLowerCase().trim();
	                            if (contentType.length()&gt;0) {
	                                sendaschunked = chunkabletypes.contains(contentType);
	                                if (!sendaschunked) {
	                                    for (String chunkabletype: chunkabletypes) {
	                                        // Begins with
	                                        if (contentType.indexOf(chunkabletype)==0) {
	                                            sendaschunked = true;
	                                            break;
	                                        }
	                                    }
	                                }
	                            }
	                        }
	                    }
	                    if (sendaschunked) {
	                        ctx.fireChannelRead(msg);
	                        return;
	                    }
	                }
	                catch(Exception ex) {
	                    logger.error(&quot;error determining chunkable viability&quot;, ex);
	                }
	            }
	        }
	        if (sendaschunked) {
	            ctx.fireChannelRead(msg);
	            return;
	        }
	
	        try {
	            super.channelRead(ctx, msg);
	            
	        } catch (Exception e) {
	            logger.error(&quot;error determining chunkable viability&quot;, e);
	            e.printStackTrace();
	        }
	    }
	}


And this is the value for the chunkable types property:  

`video/x-ms-wvx,video/x-flv,application/x-shockwave-flash,video/quicktime,video/,audio/`


Edit
---

I think this is bug in netty 4.1.30 around this line 255 in `io.netty.handler.codec.MessageAggregator`. Seems this CompositeByteBuf is allocated but not released. Am I right? I am hoping for some authoritative answer to either confirm or reject this idea.

            // A streamed message - initialize the cumulative buffer, and wait for incoming chunks.
            CompositeByteBuf content = ctx.alloc().compositeBuffer(maxCumulationBufferComponents); // LINE 255 
            if (m instanceof ByteBufHolder) {
                appendPartialContent(content, ((ByteBufHolder) m).content());
            }
            currentMessage = beginAggregation(m, content);




</details>


# 答案1
**得分**: 4

在我们的情况下，问题出在没有读取响应主体，导致字节缓冲区永远不会被释放。

原始代码：
```java
WebClient client = WebClient.create("some_url");
return client.get().exchange().flatMap(response -> Mono.just(builder.up().build()));

修正后的代码：

WebClient client = WebClient.create("some_url");
return client.get().retrieve().toBodilessEntity().flatMap(response -> Mono.just(builder.up().build()));

即使是exchange的Javadoc也指出了这一点：
> 自5.3起弃用，因为可能会导致内存和/或连接泄漏。请使用exchangeToMono(Function)、exchangeToFlux(Function)；还考虑使用retrieve()，它通过ResponseEntity提供对响应状态和标头的访问，以及错误状态处理。

致谢：https://stackoverflow.com/a/51321602/3242721

要在本地复现此问题，我使用了-Dio.netty.leakDetectionLevel=paranoid的VM参数。

英文:

In our case it was a problem in the body of the response not being read which resulted into byte buf never being released.

Original code:

WebClient client = WebClient.create(&quot;some_url&quot;);
return client.get().exchange().flatMap(response -&gt; Mono.just(builder.up().build()));

Fixed code:

WebClient client = WebClient.create(&quot;some_url&quot;);
return client.get().retrieve().toBodilessEntity().flatMap(response -&gt; Mono.just(builder.up().build()));

Even the javadoc for exchange says it:
> Deprecated since 5.3 due to the possibility to leak memory and/or connections; please, use exchangeToMono(Function), exchangeToFlux(Function); consider also using retrieve() which provides access to the response status and headers via ResponseEntity along with error status handling.

Kudos: https://stackoverflow.com/a/51321602/3242721

To reproduce the issue on localhost I used -Dio.netty.leakDetectionLevel=paranoid vm args.

答案2

得分: 1

你需要释放由你分配的 ByteBuf。这不是Netty的错误。

ByteBuf 位于 com.company.japp.protocol.http.decoders.ConditionalHttpChunkAggregator.channelRead(ConditionalHttpChunkAggregator.java:112)。

英文:

You need to release Bytebuf allocated by you. It's not a Netty bug.

ByteBuf is at com.company.japp.protocol.http.decoders.ConditionalHttpChunkAggregator.channelRead(ConditionalHttpChunkAggregator.java:112)

huangapple
  • 本文由 发表于 2020年9月4日 20:50:10
  • 转载请务必保留本文链接：https://go.coder-hub.com/63741540.html
  • java
  • netty
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